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Wiley CompTIA A+ Complete Study Guide: Exams 220-701 (Essentials) and 220-702 (Practical Application)

1. PCI Expansion Southbridge Bus Onboard USB Serial Parallel Onboard LAN Expansion Slots The most visible parts of any motherboard are the expansion slots These look like small plastic slots usually from 1 to 6 inches long and approximately inch wide As their name suggests these slots are used to install various devices in the computer to expand its capa bilities Some expansion devices that might be installed in these slots include video net work sound and disk interface cards If you look at the motherboard in your computer you will more than likely see one of the main types of expansion slots used in computers today PCI AGP PCIe AMR CNR Each type differs in appearance and function In this section we will cover how to visu ally identify the different expansion slots on the motherboard Note that Industry Standard Architecture ISA expansion slots have been removed from the CompTIA A objectives but Identifying Components of Motherboards 13 you might wish to research these slots for your own edification and to be prepared should you find yourself face to face with such a beast in the field PC Card buses such as PCMCIA are related more to laptops than to desktop computers and are covered in Chapter 4 PCI Expansion Slots Many computers in force today contain 32 bit Peripheral Component Interconnect PCI slots They are easily recognizable because they are short arou
2. SDR SDRAM PC400 does not exist PC3 3200 does not exist and is too slow for DDR3 Assuming requisite 32 bit dual channel mode SRAM Static random access memory SRAM doesn t require a refresh signal like DRAM does The chips are more complex and are thus more expensive However they are considerably faster DRAM access times come in at 40 nanoseconds ns or more SRAM has access times faster than 10ns SRAM is often used for cache memory ROM ROM stands for read only memory It is called read only because the original form of this memory could not be written to Once information had been etched on a silicon chip and manufactured into the ROM package the information couldn t be changed If you ran out of use for the information or code on the ROM you added little eyes and some cute fuzzy extras and you had a bug that sat on your desk and looked back at you Some form of ROM is normally used to store the computer s BIOS because this information normally does not change very often The system ROM in the original IBM PC contained the power on self test POST Basic Input Output System BIOS and cassette BASIC Later IBM computers and compatibles include everything but the cassette BASIC The system ROM enables the computer to pull itself up by its bootstraps or boot find and start the operating system Through the years different forms of ROM were developed that could be altered later ones more easily than earlie
3. An infrared IR port is a small port on the computer that allows data to be sent and received using electromagnetic radiation in the infrared band The infrared port itself is a small dark square of plastic usually a very dark maroon and can typically be found on the front of a PC or on the side of a laptop or portable Figure 1 40 shows an example of an infrared port FIGURE 1 40 Aninfrared port Infrared ports send and receive data at a very slow rate the maximum speed on PC infrared ports is less than 4Mbps Most infrared ports on PCs that have them support the Infrared Data Association IrDA standard which outlines a standard way of trans mitting and receiving information by infrared so that devices can communicate with one another More information on the IrDA standard can be found at the organization s A TE website http ww irda org Note that although infrared is a wireless technology most infrared communications especially those that conform to the IrDA standards are line of sight only and take place within a short distance typically less than four meters Infrared is generally used for point to point communications such as controlling the volume on a device with a handheld remote control Audio Video Jacks The RCA jack shown in Figure 1 41 was developed by the RCA Victor Company in the late 1940s for use with its phonographs You bought a phonograph connected the RCA plug on the back of your phonograph to the R
4. Parallel on top Standard serial Mouse on top Keyboard S PDIF out USB FIGURE 1 19 Peripheral ports and connectors Figure 1 20 shows an example of a game port also called a joystick port because that was the most common device that connected to it As discussed later in this chapter the game port can be used to connect to Musical Instrument Digital Interface MIDI devices Identifying Components of Motherboards 29 as well Game ports connect such peripheral devices to the computer using a DA 15F 15 pin female D subminiature D sub connector Devices that once connected to the game port have evolved for the most part into USB attached devices FIGURE 1 20 Agame port Y3LNI awy9 Figure 1 21 shows another set of interfaces not shown in Figure 1 19 the sound card jacks These jacks are known as inch 3 5mm stereo minijacks so called for their size and the fact that they make contact with both the left and right audio channels through their tip and ring Shown in the diagram are an input the microphone jack on the left and an output the speaker jack on the right Software can use these interfaces to allow you to record and play back audio content in file or CD DVD form FIGURE 1 21 Soundcard jacks 30 Chapter 1 Personal Computer System Components Motherboard Attachment There are two ways of connecting these ports to the motherboard assuming the circuitry for providing these functions i
5. 1 47 Standard DE 9 and DB 25 male serial ports FIGURE 1 48 A standard serial cable wiring diagram Pin 3 2 5 1 7 8 DB 9 6 Female 5 1 4 9 FIGURE 1 49 A null modem serial cable wiring diagram Ping Ping 5 5 5 1 2 3 5 4 3 2 DB 9 7 8 DB 9 Female 8 7 Female ae i 6 4 1 Finally because of the two different device connectors DE 9M and DB 25M serial cables have a few different configurations Table 1 4 shows the most common serial cable configurations Identifying Characteristics of Ports and Cables 67 TABLE 1 4 Common Serial Cable Configurations 1st Connector 2nd Connector Description DE 9 female DB 25 male Standard modem cable DE 9 female DE 9 male Standard serial extension cable DE 9 female DE 9 female Null modem cable DB 25 female DB 25 female Null modem cable DB 25 female DB 25 male Standard serial cable or standard serial extension cable Universal Serial Bus USB USB cables are used to connect a wide variety of peripherals to computers including key boards mice digital cameras printers and scanners The latest version of USB version 2 0 requires a cable with better shielding than did earlier versions Not all USB cables work with USB 2 0 ports The connectors are identical so perhaps look for cables that are transparent with a view to the silver metallic shielding within USB s simplicity of use and ease of expansion make it an excellent interfac
6. 2 product line can be thought of as a second generation of the Core series Core 2 by the way reunited Intel mobile and desktop computing the Pentium 4 family had a separate Pentium M for mobile computing Intel describes and markets the microcode of certain processors as Core microarchitecture As confusing as it may sound the Core 2 processors are based on the Core microarchitecture the Core processors are not Core 2 Identifying Purposes and Characteristics of Processors 37 processors come in Solo mobile only Duo and four core Quad implementations Solo and Duo processors have a single die Quad processors have two Duo dies A more capable Extreme version exists for the Duo and Quad models Processors such as certain models of AMD s Phenom series can contain an odd number of multiple cores as well The triple core processor which obviously contains three cores is the most common implementation of multiple odd cores Throttling CPU throttling allows reducing the operating frequency of the CPU during times of less demand or during battery operation CPU throttling is very common in pro cessors for mobile devices where heat generation and system battery drain are key issues of full power usage You might discover throttling in action when you use a utility that reports a lower CPU clock frequency than expected If the load on the system does not require full throttle operation there is no need to push such a limit Micro
7. CPU works it stores data and instructions in the computer s memory Contrary to what you might expect from an inexpensive solution memory upgrades tend to afford the greatest performance increase as well up to a point Motherboards have memory limits operating systems have memory limits CPUs have memory limits To identify memory within a computer look for several thin rows of small circuit boards sitting vertically packed tightly together near the processor In situations where only one memory stick is installed it will be that stick and a few empty slots that are tightly packed together Figure 1 29 shows where memory is located in a system Identifying Purposes and Characteristics of Memory 39 FIGURE 1 29 Location of memory within a system Important Memory Terms There are a few technical terms and phrases that you need to understand with regard to memory and its function These include Parity checking Error checking and correcting ECC Single and double sided memory Single and dual channel memory These terms are discussed in detail in the following sections Parity Checking and Memory Banks Parity checking is a rudimentary error checking scheme that offers no error correction Parity checking works most often on a byte or 8 bits of data A ninth bit is added at the transmit ting end and removed at the receiving end so that it does not affect the actual data transmit ted The four most common parity
8. The details of the various devices in the computer and their impact on computer service prac tices will be covered in later chapters FIGURE 1 3 Components on a motherboard Microprocessor fan Microprocessor SEC cartridge connector J4J1 connector J4M1 Power input connector POWER Keyboard pa ee el ra oH Mouse connector MSE THT USB connectors USBO USB1 3 3 power input connector 3 3 Serial port connector COM1 Chassis cooling fan connector J8M1 Diskette drive interface connector FLOPPY Parallel port connector PARALLEL a4 SCSI hard disk drive access indicator cable connector J8J1 Onboard audio controller jacks LINE OUT LINE IN and MIC IN yl Control panel connector J8H1 MIDI game port connector GAME o H H iyo CD ROM drive audio cable connector owe Primary EIDE channel connector PRI IDE Secondary EIDE channel connector SEC IDE Modem audio cable connector for using audio system as speaker phone TELPH DIMM sockets BANK 0 BANK 1 BANK 2 Auxiliary line in audio connector AUX IN Oy Accelerated graphics port connector AGP Battery socket B7C1 PCI expansion card connectors PCI1 PCI2 PCI3 PC14 o H Configuration jumper J8A1 ISA expansion card connector A o Speaker U8A1 ISA1 an
9. You have just purchased a motherboard that has an LGA775 socket for an Intel Pentium 4 processor What type of memory modules will you need for this motherboard A DIP B SIMM C RIMM D DIMM 20 What type of expansion slot is preferred today for high performance graphics adapters A AGP B PCle Cc PCI D ISA 84 Chapter 1 Personal Computer System Components Answers to Review Questions 1 A The spine of the computer is the system board otherwise known as the motherboard On the motherboard you will find the CPU underlying circuitry expansion slots video components RAM slots and various other chips 2 C DDR SDRAM is manufactured on a 184 pin DIMM DIMMs with 168 pins were used for SDR SDRAM The SIMM is the predecessor to the DIMM on which SDRAM was never deployed RIMM is the Rambus proprietary competitor for the DIMM that carries DRDRAM instead of SDRAM 3 B Remember the 8 1 rule Modules greater than but not including SDR SDRAM are named with a number 8 times larger than the number used to name the chips on the module The initials PC are used to describe the module the initials DDR for the chips and a number to represent the level of DDR The lack of a number represents DDR as long as the associated number is greater than 133 Otherwise you re dealing with SDR This means that PC3 16000 modules are DDR3 modules and are populated with chips named DDR3 and a number that is of the module s numeric
10. a serial cable DA15 Female Game port or MIDI port DA15 Male Connector on a game peripheral cable or MIDI cable DE15 Female Video port has three rows of 5 pins as opposed to two rows DE15 Male Connector on a monitor cable 56 Chapter 1 Personal Computer System Components FIGURE 1 36 D sub ports and connectors RJ Series Registered jack RJ connectors are most often used in telecommunications The two most common examples of RJ ports are RJ 11 and RJ 45 RJ 11 connectors are used most often in telephone hookups your home phone jack is probably an RJ 11 jack The ports in your external and internal modems assuming you still have one are RJ 11 RJ 45 connectors on the other hand are most commonly found on Ethernet networks that use twisted pair cabling Your Ethernet NIC likely has an RJ 45 socket on it See Chapter 10 Understanding Networking for details on networking interfaces Although RJ 45 is a widely accepted description for the larger connectors it is not correct Generi cally speaking they are 8 pin modular connectors or 8P8C connectors meaning there are 8 pin positions and all 8 of them are connected or used RJ 45 not only specifies the physical appearance of the connector but also how the contacts are wired from one end to the other That specification does not match the T568A and T568B wiring standards used in data communications Figure 1 37 shows an RJ 11 connector on the left and an RJ 45 connector o
11. a x1 slot but shorter than a x16 slot Every PCle slot has a 22 pin portion in common toward the rear of the motherboard which you can see in Figure 1 8 which orients the rear of the motherboard to the left These 22 pins comprise mostly volt age and ground leads There are three major versions of PCIe currently specified 1 x 2 0 and 3 0 For these three versions a single lane and hence a x1 slot operates in each direction or transmit and receive from either communicating device s perspective at a data rate of 250MBps almost twice the rate of the most common PCI slot SOOMBps and 1GBps respectively Combin ing lanes results in a linear multiplication of these rates For example a PCIe 1 1 x16 slot is capable of 4GBps of throughput in each direction 16 times the 250MBps x1 rate As you can see this fairly common slot doubles the throughput of an AGP 8x slot Later PCIe specifications increase this data rate even more Up plugging is defined in the PCle specification as the ability to use a TE higher capability slot for a lesser adapter In other words you can use a shorter fewer lane card in a longer slot For example you can insert a x8 card into a x16 slot The x8 card won t completely fill the slot but it will work at x8 speeds if up plugging is supported by the motherboard Other wise the specification only requires up plugged devices to operate at the x1 rate something to be aware of and investigate in advance Down plu
12. applied during attachment will equalize the compound quite well During attachment watch for oozing compound around the edges clean it off immediately and use less next time 76 Chapter 1 Personal Computer System Components Improving and Maintaining CPU Cooling In addition to using thermal compound you can enhance the cooling efficiency of a CPU heat sink by lapping the heat sink which smoothes the mating surface using a very fine sanding element about 1000 grit in the finishing stage Some vendors of the more expensive heat sinks will offer this service as an add on If your CPU has been in service for an extended period of time perhaps three years or more it is a smart idea to remove the heat sink and old thermal compound and then apply fresh thermal compound and reattach the heat sink Be careful though if your thermal paste has already turned into thermal glue you can wrench the processor right out of the socket even with the release mechanism locked in place Invariably this damages the pins on the chip Counterintuitively perhaps you can remove a released heat sink from the processor by gently rotating the heat sink to break the paste s seal If the CPU has risen in the socket already however this would be an extremely bad idea Sometimes after you realize that the CPU has risen a bit and that you need to release the mechanism holding it in to reseat it you find the release arm is not accessible with the h
13. low power mobile Athlon XP M Intel Xeon Intel Xeon with Micro Flip chip PGA FCPGA package Athlon 64 Sempron Turion 64 For 478 pin Micro FCPGA mobile packages such as Core 2 Duo Celeron M and Pentium Dual Core Desktop processors such as Pentium 4 Pentium D Celeron D Pentium Extreme Edition Core 2 Duo Core 2 Extreme Core 2 Quad Server version of LGA 775 Dual Core Xeon Intel Core i7 Athlon 64 Athlon 64 FX Athlon 64 X2 Opteron 100 series Intended for AMD servers Athlon 64 FX FX 51 Opteron 24 Chapter 1 Personal Computer System Components TABLE 1 1 Socket Slot Types and the Processors They Support continued Socket Slot Processors Socket F Socket 1207 Replaces Socket 940 when used with Opteron multiprocessor systems LGA packaging Socket AM2 AMD single processor systems 940 pins not same as server based Socket 940 replaces Socket 754 and Socket 939 Socket AM3 DDR3 capable for Phenom series Athlon X2 Sempron LE Opteron single CPU servers Socket S1 AMD based mobile platforms replaces Socket 754 in the mobile sector PAC418 Itanium instead of proposed Slot 3 Slot M PAC611 Itanium 2 Power Connectors In addition to these sockets and slots on the motherboard a special connector the 20 pin block connector shown in Figure 1 15 allows the motherboard to be connected to the power supply to receive power This connector is where the ATX power connector men tioned in Chapter 2 in the sect
14. shows the ZIF locking mechanism at the edge of the socket along the bottom of the photo For processors based on the LGA concept a socket with a different locking mechanism is used Because there are no receptacles in either the motherboard or the CPU there is no opportunity for a locking mechanism that holds the component with the pins in place Identifying Components of Motherboards 21 LGA compatible sockets as they re called despite the misnomer have a lid of sorts that closes over the CPU and is locked in place by an L shaped arm that borders two of the socket s edges The nonlocking leg of the arm has a bend in the middle that latches the lid closed when the other leg of the arm is secured The bottom image in Figure 1 13 shows an LGA socket with no CPU installed and the locking arm secured over the lid s tab right hand edge in the photo FIGURE 1 13 CPU socket examples 22 Chapter 1 Personal Computer System Components The processor slot is another method of connecting a processor to a motherboard but one into which a processor such as the AMD Athlon or the Intel Pentium II or Pentium II on a special expansion card is inserted the slot shown in Figure 1 14 Newer more com plex processors such as the Intel Itanium use a similar packaging known as a Pin Array Cartridge PAC which uses a complex mechanism for inserting the large rectangular PAC CPU carrier The connector that receives a PAC works on the Very Low Ins
15. simplify its comparison with other bus technologies In fact unlike true I O buses which share total bandwidth among all slots in a hub like interconnectivity PCIe uses a switching component with point to point connections to slots giving each component full use of the corresponding bandwidth Fur thermore true bus architectures are parallel in nature while PCle is a serial technology striping data packets across multiple serial paths to achieve higher data rates PCle uses the concept of lanes which are the switched point to point signal paths between any two PCIe components Each lane that the switch interconnects between any two intercommunicating devices comprises a separate pair of wires for both directions of traffic Each PCle pairing between cards requires a negotiation for the highest mutually supported number of lanes The single lane or combined collection of lanes that the switch interconnects between devices is referred to as a link There are seven different link widths supported by PCle designated x1 pronounced by 1 x2 x4 x8 x12 x16 and x32 with x1 x4 and x16 the most common The x8 link width is less common than these but more common than the others A slot that sup ports a particular link width is of a size related to that width because the width is based Identifying Components of Motherboards 15 on the number of lanes supported which requires a related number of wires Therefore a x8 slot is longer than
16. the metallic pins on each memory module Small metal or plastic tabs on each side of the slot keep the memory module securely in its slot Identifying Components of Motherboards 19 Sometimes the amount of primary memory installed is inadequate to service additional requests for memory resources from newly launched applications When this condition occurs the user receives an out of memory error and the application fails to launch One solution for this is to use the hard drive as additional RAM This space on the hard drive is known as a swap file or a paging file The technology in general is known as virtual memory The swap file pagefile sys in modern Microsoft operating systems is a contigu ous optimized space that can deliver information to RAM at the request of the memory controller faster than if it came from the general storage pool of the drive Note that virtual memory cannot be used directly from the hard drive it must be paged into RAM as the oldest contents of RAM are paged out to the hard drive to make room The memory con troller by the way is the chip that manages access to RAM as well as adapters that have had a few hardware addresses reserved for their communication with the processor Nevertheless relying too much on virtual memory check your page fault statistics in the Reliability and Performance Monitor results in the entire system slowing down noticeably An inexpensive and highly effective solution is to add
17. the special tricks that are played with memory subsystems to improve over all system performance care must be taken during the installation of disparate memory modules In the worst case the computer will cease to function when modules of different speeds different capacities or different numbers of sides are placed together in slots of the same channel If all of these parameters are identical there should be no problem with pairing modules Nevertheless problems could still occur when modules from two differ ent manufacturers or certain unsupported manufacturers are installed all other param eters being the same Technical support or documentation from the manufacturer of your motherboard should be able to help with such issues 42 Chapter 1 Personal Computer System Components Although it s not the make up of the memory that leads to dual channel support but instead the technology on which the motherboard is based some memory manufacturers still package and sell pairs of memory modules in an effort to give you peace of mind when you re buying memory for a system that implements dual channel memory architecture Keep in mind the motherboard memory slots have the distinctive color coding not the memory modules I Can t Fill All My Memory Slots As a reminder most motherboard manufacturers document the quantity and types of mod ules that their equipment supports Consult your documentation whether in print or online whe
18. to improve the thermal transfer efficiency as much as possible To that end cooling engineers came up with a compound that helps to bridge the extremely small gaps between the CPU and the heat sink which avoids superheated pockets of air that can lead to focal damage of the CPU This product is known as thermal transfer compound or simply thermal compound alternatively thermal grease or thermal paste and can be bought in small tubes Single use tubes alleviate the guessing involved with how much you should apply Watch out though this stuff makes quite a mess and doesn t want to come off your fingers very easily Apply the compound by placing a bead in the center of the heat sink not on the CPU because some heat sinks don t cover the entire CPU package That might sound like an issue but some CPUs don t have heat producing components all the way out to the edges Some CPUs even have a raised area directly over where the silicon die is within the pack aging resulting in a smaller contact area between the components You should apply less than you think you need because the pressure of attaching the heat sink to the CPU will spread the compound across the entire surface in a very thin layer It s advisable to use a clean lint free applicator of your choosing to spread the compound around a bit as well just to get the spreading started You don t need to concern yourself with spreading it too thoroughly or too neatly because the pressure
19. to occur in both directions and at rated speeds Parallel Interfaces and Cables Most parallel interfaces use a DB 25 female connector as shown earlier in this chapter Most parallel cables use a DB 25 male connector on one end and either a DB 25 male connector or Centronics 36 connector on the other The original printer cables typically used the DB 25M to Centronics 36 configuration Inside a parallel cable eight wires are used for transmitting data so one byte can be transmitted at a time Figure 1 45 shows an example of a typical parallel cable in this case a printer cable If a printer today uses a parallel port through which to connect to the computer a possible interface on the printer is known as a mini Centronics Figure 1 46 shows the component end of a mini Centronics cable The mini Centronics did not enjoy the success expected due to design issues regarding attachment reliability Again however nothing is more popular today for printer connectivity than USB so efforts to perpetuate the use of and improve the mini Centronics were abandoned FIGURE 1 45 Atypical parallel cable Identifying Characteristics of Ports and Cables 65 FIGURE 1 46 The mini Centronics connector Serial If standard parallel communications were similar to taking the interstate then RS 232 serial communications were similar to taking a country road In serial communications bits of data are sent one after another single file if you will dow
20. CA jack on the back of your radio or televi sion and used the speaker and amplifier in the radio or television to listen to records It made phonographs cheaper to produce and had the added bonus of making sure everyone had an RCA Victor radio or television or at the very least one with the RCA jack on the back Either way RCA made money 60 Chapter 1 Personal Computer System Components FIGURE 1 41 An RCA jack female and RCA plug male Female Male Today RCA jacks and connectors or plugs are used to transmit both audio and video information Typically when you see a yellow coded RCA connector on a PC video card next to a DE15F connector it s for composite video output output to a television or VCR However digital audio can be implemented with S PDIF which can be deployed with an RCA jack Figure 1 19 showed an S PDIF RCA jack Other options for S PDIF include BNC coaxial and TOSLINK fiber connectors Toshiba s TOSLINK interface is a digital fiber optic audio technology that is implemented with its own connector Although they aren t used for video it bears mentioning that the inch stereo mini jack and mating miniplug are more commonly used on computers these days for analog audio Your sound card microphone and speakers have them Figure 1 42 is a photo of a TOSLINK optical interface with a flip up cover and pictured to the left of a set of standard analog minijacks FIGURE 1 42 The TOSLINK inte
21. PCI slots on the motherboard and are slightly shorter than the PCI slots Another landmark to look for when identifying later AGP slots is the often alternate colored shell surrounding the slot with an extension toward the front of the system that snaps into place at the rear of the adapter It is necessary to pull the extension away from the adapter before removing it from the slot Figure 1 7 shows an example of an AGP slot along with a PCI slot for comparison Notice the difference in length between the two 14 Chapter 1 Personal Computer System Components FIGURE 1 7 An AGP slot compared to a PCI slot AGP slot AGP performance is based on the original specification known as AGP 1x It uses a 32 bit 4 byte channel and a 66MHz clock resulting in a data rate of 266 67MBps AGP 2x 4x and 8x specifications multiply the 66MHz clock they receive to increase throughput linearly For instance AGP 8x uses the 66MHz clock to produce an effective clock frequency of 533MHz resulting in throughput of 2133 33MBps over the 4 byte channel PCle Expansion Slots A newer expansion slot architecture that is being used by motherboards is PCI Express PCle It was designed to be a replacement for AGP and PCI It has the capability of being faster than AGP while maintaining the flexibility of PCI And motherboards with PCIe might have regular PCI slots for backward compatibility with PCI PCle is casually referred to as a bus architecture to
22. SAMPLE CHAPTER 1 Covers Both 220 701 and 220 702 Exams Includes Real World Scenarios Hands On Exercises and Leading Edge Exam Prep Software Featuring Custom Testing Engine Six Practice Exams 3 Each for A Essentials and Practical Application Electronic Flashcards Entire Book in PDF Complete STUDY GUIDE CompTIA A 220 701 Essentials Quentin Docter CompTIA A 220 702 Practical Application Emmett D ul an ey Toby Skandier CssyBEx SERIOUS SKILLS y Personal Computer System Components THE FOLLOWING COMPTIA A ESSENTIALS EXAM OBJECTIVES ARE COVERED IN THIS CHAPTER v 1 2 Explain motherboard components types and features Form Factor ATX BTX micro ATX NLX O interfaces Sound Video USB 1 1 and 2 0 Serial IEEE 1394 FireWire Parallel NIC Modem PS 2 Memory slots RIMM DIMM SODIMM SIMM Processor sockets Bus architecture Bus slots PCI AGP PCle AMR CNR PCMCIA Chipsets BIOS CMOS Firmware POST CMOS battery Riser card daughterboard Additional subobjectives covered in chapter 2 v 1 4 Explain the purpose and characteristics of CPUs and their features Identify CPU types AMD Intel Hyper threading Multi core Dual core Triple core Quad core Onchip cache 1 a g L2 ig Speed real vs actual o 32 bit vs 64 bit v 1 5 Explain cooling methods and devi
23. at Pipes Heat pipes are closed systems that employ some form of tubing filled with a liquid suitable for the applicable temperature range Pure physics are used with this technology to achieve cooling to ambient temperatures no outside mechanism is used One end of the heat pipe is heated by the component being cooled This causes the liquid at the heated end to evaporate and increase the relative pressure at that end of the heat pipe with respect to the cooler end This pressure imbalance causes the heated vapor to equalize the pressure by migrating to the cooler end where the vapor condenses and releases its heat warming the nonheated end of the pipe The cooler environment surrounding this end transfers the heat away from the pipe by convection The condensed liquid drifts to the pipe s walls and is drawn back to the heated end of the heat pipe by gravity or by a wicking material or texture that lines the inside of the pipe Once the liquid returns the process repeats Peltier Cooling Devices Water and air cooling devices are extremely effective by themselves but they are more effective when used with a device known as a Peltier cooling element These devices also known as thermoelectric coolers TECs facilitate the transfer of heat from one side of the element made of one material to the other side made of a different material Thus they have a hot side and a cold side The cold side should always be against the CPU sur face and op
24. at you actually see The external pins you see are structures that can withstand insertion into a socket and that are carefully threaded from the wafer s minuscule con tacts Just imagine how fragile the structures must be that you don t see Older CPUs are generally square with contacts arranged in a pin grid array PGA Prior to 1981 chips were found in a rectangle with two rows of 20 pins known as a dual inline package DIP see Figure 1 27 There are still integrated circuits that use the DIP form fac tor However the DIP form factor is no longer used for PC CPUs Most CPUs use either the PGA or the single edge contact cartridge SECC form factor SECC is essentially a PGA type socket on a special expansion card FIGURE 1 27 DIPandPGA As processor technology grows and motherboard real estate stays the same more must be done with the same amount of space To this end the staggered PGA SPGA layout was developed An SPGA package arranges the pins in what appears to be a checkerboard pat tern but if you angle the chip diagonally you ll notice straight rows closer together than the right angle rows and columns of a PGA This feature allows a higher pin count per area Intel and AMD are migrating toward the use of an inverted socket processor combi nation of sorts As mentioned earlier the land grid array LGA packaging calls for the pins to be placed on the motherboard while the mates for these pins are on the processor pa
25. can be cooled and how overheating can be prevented 80 Chapter 1 Personal Computer System Components Review Questions 1 Which computer component contains all the circuitry necessary for other components or devices to communicate with one another A Motherboard B Adapter card C Hard drive D Expansion bus 2 Which packaging is used for DDR SDRAM memory A 168 pin DIMM B 72 pin SIMM C 184 pin DIMM D RIMM 3 What memory chips would you find on a stick of PC3 16000 A DDR 2000 B DDR3 2000 C DDR3 16000 D PC3 2000 4 Which motherboard design style is most widely implemented A ATX B AT C Baby AT D NLX 5 Which motherboard socket type is used on the Pentium 4 chip A Slot1 B Socket A C Socket 370 D Socket 478 6 Which of the following is a socket technology that is designed to ease insertion of modern CPUs A Socket 479 B ZIF C LPGA D SPGA 10 11 12 Review Questions 81 Which of the following is not controlled by the Northbridge A PCIe B SATA C AGP D Cache memory Which of the following is used to store data and programs for repeated use Information can be added and deleted at will and it does not lose its data when power is removed A Hard drive B RAM C Internal cache memory D ROM Which motherboard socket type is used with the AMD Athlon XP A Slot 1 B Socket A C Socket 370 D Socket 478 You want to plug a keyboard into the back of a compute
26. cards onto the mother board itself In the early 1990s these components had to be added to the motherboard using expansion slots Integrated system board Most of the components that would otherwise be installed as expansion cards are integrated into the motherboard circuitry Integrated system boards were designed for simplicity Of course there s a drawback to this simplicity when one component breaks you can t just replace the component that s broken the whole motherboard must be replaced Although these boards are cheaper to produce they are more expensive to repair 6 Chapter 1 Personal Computer System Components With integrated system boards there is a way around having to replace the whole mother board when a single component breaks On some motherboards you can disable the malfunc tioning onboard component for example the sound circuitry and simply add an expansion card to replace its functions System Board Form Factors System boards are also classified by their form factor design ATX micro ATX BTX or NLX and variants of these Exercise care and vigilance when acquiring a motherboard and case separately Some cases are less flexible than others and might not accommodate the motherboard you choose Advanced Technology Extended ATX The ATX motherboard has the processor and memory slots at right angles to the expansion cards This arrangement puts the processor and memory in line with the fan output of
27. cation Collectively these rules make cabling your USB subsystem quite straightforward Although the system receptacle the Type A remains somewhat of a constant the compo nent receptacle often differs usually based on the size of the USB device For example a USB attached printer is large enough for a Type B connector but a compact digital camera might only be large enough to accommodate a Mini B receptacle of some sort While the standard calls for one Mini B connector others have been developed some common others a bit rarer The four connectors shown in Figure 1 50 are the most common You might also run across older rare Mini A connectors or newer small form factor interfaces called Micro A and Micro B none of which are discussed further in this book USB connectors are keyed and will go into a USB port only one way If the P connector will not go into the port properly try rotating it A For more information on USB check out http www usb org I IEEE 1394 FireWire The IEEE 1394 interface is about one thing speed Its first iteration now known as FireWire 400 has a maximum data throughput of 400Mbps in half duplex The next iteration FireWire 800 specified under IEEE 1394b has a maximum data throughput of 800Mbps and works in full duplex FireWire 400 carries data over a maximum cable length of 4 5 meters with a maximum of 63 devices connected to each interface on the computer Using new beta connectors and associa
28. ces A Eja Heat sinks 7 CPU and case fans J vd SOS NENS k Liquid cooling systems Thermal compound v 1 6 Compare and contrast memory types characteristics and their purpose Types DRAM SRAM SDRAM DDR DDR2 DDR3 RAMBUS Parity vs Non parity ECC vs non ECC Single sided vs double sided Single channel vs dual channel Speed PC100 PC133 PC2700 PC3200 DDR3 1600 DDR2 667 A personal computer PC is a computing device made up of ps many distinct electronic components that all function together BRAS in order to accomplish some useful task such as adding up the numbers in a spreadsheet or helping you write a letter Note that this definition describes a computer as having many distinct parts that work together Most computers today are modular That is they have components that can be removed and replaced with a compo nent of similar function in order to improve performance Each component has a specific function In this chapter you will learn about the components that make up a typical PC what their functions are and how they work together inside the PC Unless specifically mentioned otherwise throughout this book the terms 2 TE PC and computer can be used interchangeably In this chapter you will learn how to identify system components common to most personal computers including the following Motherboards Processors Memory Co
29. ck aging As with PGA LGA is named for the landmarks on the processor not the ones on the Identifying Purposes and Characteristics of Processors 35 motherboard As a result the grid of metallic contact points called lands on the bottom of the CPU gives this format its name This discussion only scratches the surface of the topic surrounding chip TE packaging and carriers For more information on the various packaging for chips start with en wikipedia org wiki Category Chip_carriers You can easily identify which component inside the computer is the CPU because it is a large square lying flat on the motherboard with a very large heat sink and fan as shown earlier in Figure 1 12 Or if the CPU is installed in a Slot 1 motherboard it is a large inch thick expansion card with a large heat sink and fan integrated into the package It is located away from the expansion cards Figure 1 28 shows the location of the CPU in relation to the other components on a typical ATX motherboard Notice how prominent the CPU is FIGURE 1 28 The location of a CPU inside a typical computer CPU Modern processors can feature the following Hyperthreading This term refers to Intel s Hyper Threading Technology HTT HTT is a form of simultaneous multithreading SMT SMT takes advantage of a modern CPU s superscalar architecture Superscalar processors are able to have multiple instructions oper ating on separate data in parallel HTT capab
30. code 2000 4 lt A Although all the motherboard design styles listed are in use today the ATX motherboard style and its derivatives is the most popular design 5 D Most Pentium 4 chips use the Socket 478 motherboard CPU socket although not exclusively Nevertheless no other option listed is used for these processors 6 B ZIF sockets are designed with a locking mechanism that when released alleviates the resistance of the socket to receiving the pins of the chip being inserted Make sure you know your socket types so that the appearance of a specific model such as Socket 479 in a question like this does not distract you from the correct answer Only LGA would be another acceptable answer to this question because with a lack of pin receptacles there is no insertion resistance However no other pin layout format such as SPGA addresses issues with inserting chips LPGA might have evoked an image of LGA leading you to that answer but that term means nothing outside of the golfing community 7 B The Northbridge is in control of the local bus components that share the clock of the frontside bus SATA and all other drive interfaces do not share this clock and are controlled by the Southbridge 8 A A hard drive stores data on a magnetic medium which does not lose its information after the power is removed and which can be repeatedly written to and erased 9 B The Socket A remember A for AMD motherboard socket is used prima
31. code and multimedia extensions Microcode is the set of instructions known as an instruction set that make up the various microprograms that the processor executes while carrying out its various duties The Multimedia Extensions MMX microcode is a specialized example of a separate microprogram that carries out a particular set of functions Microcode is at a much lower level than the code that makes up application programs Each instruction in an application will end up being represented by many microinstructions on average The MMX instruction set is incorporated into most modern CPUs from Intel and others MMX came about as a way to take much of the multimedia processing off the CPU s hands leaving the processor to other tasks Think of it as sort of a coprocessor for multimedia much like the floating point unit FPU is a math coprocessor Cache As mentioned in the Memory Slots and Cache section earlier in this chapter cache is a very fast chip memory that is used to hold data and instructions that are most likely to be requested next by the CPU The cache located on the CPU die is known as L1 cache and is generally of a smaller capacity in comparison to L2 cache which is located on the mother board or off die in the same CPU packaging When the CPU requires outside information it believes it requests that information from RAM The cache controller however intercepts the request and consults its tag RAM to discover if the requested i
32. d ISA2 For systems with onboard audio Bus Architecture Many components of a computer system work on the basis of a bus A bus in this sense is a common collection of signal pathways over which related devices communicate within the computer system Expansion buses of various architectures such as PCI and AGP incorpo rate slots at certain points in the bus to allow insertion of external devices or adapters into the bus usually with no regard to which adapters are inserted into which slots insertion is generally arbitrary Other buses exist within the system to allow communication between the CPU and other components with which data must be exchanged Except for CPU slots and sockets and memory slots there are no insertion points in such closed buses because no adapters exist for such an environment 10 Chapter 1 Personal Computer System Components The term bus is also used in any parallel or bit serial wiring implementation where multi ple devices can be attached at the same time in parallel or in series daisy chained Examples include Universal Serial Bus USB Small Computer System Interface SCSI and Ethernet Chipsets A chipset is a collection of chips or circuits that perform interface and peripheral functions for the processor This collection of chips is usually the circuitry that provides interfaces for memory expansion cards and onboard peripherals and generally dictates how a mother board will communicate with th
33. ding the aluminum heat spreaders 52 Chapter 1 Personal Computer System Components FIGURE 1 32 A pair of DDR3 SDRAM modules 00091 69d Bl OA TUONTUENTANAUO ATTA a ss FIGURE 1 33 A Rambus RIMM module f N N ofetedntadedotababebntabsdninisdebntabaihonny mmidi Identifying Purposes and Characteristics of Memory 53 As mentioned earlier DRDRAM is based on a 16 bit channel However dual channel implementation is required with DRDRAM it s not an option The dual channel archi tecture can be implemented utilizing two separate 16 bit RIMMs leading to the generally held view that RIMMs must always be installed in pairs or the newer 32 bit single module design not doing much to dispel the pair view despite the facts Typically mother boards with the 16 bit single or dual channel implementation provide four RIMM slots that must be filled in pairs while the 32 bit versions provide two RIMM slots that can be filled one at a time A 32 bit RIMM essentially has two 16 bit modules built in possibly contributing to the persistence of the pair view and requires only a single motherboard slot albeit a physically different slot So you must be sure of the module your motherboard accepts before upgrading Unique to the use of RIMM modules a computer must have every RIMM slot occu pied Even one vacant slot will cause the computer not to boot Any slot not populated with live memory requires an inexpe
34. ds 33 from electrostatic discharge ESD Another ramification is that it doesn t take much of a power source to keep CMOS chips from losing their contents To prevent CMOS from losing its rather important information motherboard manu facturers include a small battery called the CMOS battery to power the CMOS memory The batteries come in different shapes and sizes but they all perform the same function Most CMOS batteries look like large watch batteries or small cylindrical batteries Today s CMOS batteries are most often of a long life nonrechargeable lithium chemistry Jumpers and DIP Switches The last components of the motherboard we will discuss in this section are jumpers and DIP switches These two devices are used to configure various hardware options on the motherboard For example some motherboards support processors that use different core internal and I O external voltages You must set the motherboard to provide the cor rect voltage for the processor it is using You do so by changing a setting on the mother board with either a jumper or a DIP switch Figure 1 26 shows both a jumper set and DIP switches Motherboards often have either several jumpers or one bank of DIP switches Individual jumpers are often labeled with the moniker JPx where x is a unique number for the jumper FIGURE 1 26 Jumpers and DIP switches Many of the motherboard settings that were set using jumpers and DIP A TE switches are now eith
35. dvantages it has some drawbacks that keep it from taking over the market Increased latency heat output complexity in the manufacturing pro cess and cost are the primary shortcomings The additional heat that individual DRDRAM chips put out led to the requirement for heat sinks on all modules High manufacturing costs and high licensing fees led to triple the cost to consumers over SDR although today there is more parity between the prices In 2003 free from its contractual obligations to Rambus Intel released the i875P chipset This new chipset provides support for a dual channel platform using standard PC3200 DDR modules Dual channel DDR transfers 16 bytes 128 bits per read write request giving PC3200 a total throughput rate of 6400MBps As a result and because of the advent of DDR2 and DDR3 DRDRAM no longer holds any performance advantage To put each of the SDRAM types into perspective consult Table 1 2 which sum marizes how each technology in the SDRAM arena would achieve a transfer rate of 3200MBps even if only theoretically For example PC400 doesn t exist in the SDR SDRAM world Identifying Purposes and Characteristics of Memory 49 TABLE 1 2 How Some Memory Types Transfer 3200MBps per Channel Actual Effective FSB Clock Memory Type Frequency MHz Bytes per Transfer SDR SDRAM PC400 400 400 8 DDR SDRAM PC3200 200 400 8 DDR2 SDRAM PC2 3200 100 400 8 DDR3 SDRAM PC3 3200 50 400 8 DRDRAM PC800 400 800 4
36. e a DB 25 female connector on the computer to transfer data to peripherals Parallel was faster than the original serial technology which was also once used for printers in electrically noisy environments or at greater distances from the com puter but the advent of USB has brought serial fast serial back to the limelight The most common use of the parallel interface is printer communication There are three major types standard bidirectional and enhanced parallel ports Let s look at the differences between the three Standard Parallel Ports The standard parallel port only transmits data out of the computer It cannot receive data except for a single wire carrying a Ready signal This parallel port came with the original IBM PC XT and AT It can transmit data at 150KBps and is commonly used to transmit data to printers This technology also had a maximum transmission distance of 10 feet Bidirectional Parallel Ports As its name suggests the bidirectional parallel port has one important advantage over a standard parallel port it can both transmit and receive data These parallel ports are capable of interfacing with such devices as external CD ROM drives and external paral lel port backup drives Zip Jaz and tape drives Most computers made since 1994 have a bidirectional parallel port M In order for bidirectional communication to occur properly the cable must P support bidirectional communication as well Enhanced Paral
37. e for just about any kind of peripheral This fact alone makes the USB interface one of the most popular on the modern computer perhaps behind only the video input and network connectors The USB interface is fairly straightforward Essentially it was designed to be Plug and Play just plug in the peripheral and it should work providing the software is installed to support it The USB cable varies based on the USB male connector on each end Because there can be quite a number of daisy chained USB devices on a single system it helps to have a scheme to clarify their connectivity The USB standard specifies two broad types of connectors They are designated Type A and Type B connectors A standard USB cable has some form of Type A connector on one end and some form of Type B connector on the other end Figure 1 50 shows four USB cable connectors From left to right they are TypeA Standard Mini B Type B Alternate Mini B One part of the USB interface specification that makes it so appealing is the fact that if your computer runs out of USB ports you can simply plug a device known as a USB hub into one of your computer s USB ports which will give you several more USB ports from one USB port Figure 1 51 shows an example of a USB hub 68 Chapter 1 Personal Computer System Components Be aware of the limitations in the USB specification The commonly quoted length limit for USB cables is 5 meters If you use hubs you should
38. e industry uses DDR200 memory chips to manufac ture PC1600 memory modules Let s make sure you grasp the relationship between the speed of the FSB and the name for the related chips as well as the relationship between the name of the chips or the speed of the FSB and the name of the modules Consider an FSB of 400MHz meaning an actual clock signal of 200MHz by the way the FSB is double the actual clock for DDR remember It should be clear that this motherboard requires modules populated with DDR400 chips and that you ll find such modules on the PC3200 rack 46 Chapter 1 Personal Computer System Components Let s try another What do you need for a motherboard that features a 333MHz FSB actual clock is 166MHz Well just using the 8 1 rule mentioned earlier you might be on the lookout for a PC2667 module However note that sometimes the numbers have to be played with a bit to come up with the industry s marketing terms You ll have an easier time finding PC2700 modules that are designed specifically for a motherboard like yours with an FSB of 333MHz The label isn t always technically accurate but round numbers sell bet ter perhaps The important concept here is that if you find PC2700 modules and PC2667 modules there s absolutely no difference they both have a 2667MBps throughput rate Go for the best deal just make sure the memory manufacturer is reputable DDR2 SDRAM Think of the 2 in DDR2 as yet another m
39. e installed peripherals Chipsets are usually given a name and model number by the original manufacturer For example if you see that a motherboard has a VIA KT7 chipset you would know that the circuitry for controlling peripherals was designed by VIA and was given the designation KT7 Typically the manufacturer and model also tell you that your particular chipset has a certain set of features for example onboard video of a certain type brand onboard audio of a particular type and so on Chipsets can be made up of one or several integrated circuit chips Intel based moth erboards typically use two chips whereas the SiS chipsets typically use one To know for sure you must check the manufacturer s documentation The functions of chipsets can be divided into two major functional groups called Northbridge and Southbridge Let s take a brief look at these groups and the functions they perform Northbridge The Northbridge subset of a motherboard s chipset is the set of circuitry or chips that per forms one very important function management of high speed peripheral communications The Northbridge subset is responsible primarily for communications with integrated video using AGP and PCI Express for instance and processor to memory communications There fore it can be said that much of the true performance of a PC relies on the specifications of the Northbridge component and its communications capability with the peripherals it contr
40. eat sink in place This is an unfortunate predicament that will present plenty of opportunity to learn If you ve ever installed a brand new heat sink onto a CPU you ve most likely used ther mal compound or the thermal compound patch that was already applied to the heat sink for you If your new heat sink has a patch of thermal compound preapplied don t add more If you ever remove the heat sink don t try to reuse the patch or any other form of thermal compound Clean it all off and start fresh Advanced CPU Cooling Methods Advancements in air cooling have led to products like the Scythe Ninja 2 which is a stack of thin aluminum fins with copper tubing running up through them Some of the hottest running CPUs can be passively cooled with a device like this using only the existing air movement scheme from your computer s case Adding a fan to the side however adds to the cooling efficiency but also to the noise level In addition to standard and advanced air cooling methods there are other methods of cooling a CPU and other chips as well These methods might appear somewhat unortho dox but often deliver extreme results gmi These methods can also result in permanent damage to your computer so NING try them at your own risk Identifying Purposes and Characteristics of Cooling Systems 77 Liquid Cooling Liquid cooling is a technology whereby a special water block is used to conduct heat away from the processor as we
41. ed a memory module populated with DDR3 1600 chips because the chips are always named for the FSB speed Using the 8 1 module to chip FSB naming rule the modules you need would be called PC3 12800 supporting a 12800MBps throughput The earliest DDR3 chips however were based on a 100MHz actual clock signal so we can build on our earlier example which was also based on an actual clock rate of 10OMHz With 8 operations per cycle the FSB on DDR3 motherboards is rated at 800MHz quite a lot of efficiency while still not needing to change the original clock our examples began with Applying the 8 1 rule again the resulting RAM modules for this motherboard are called PC3 6400 and support a throughput of 6400MBps carrying chips called DDR3 800 again named for the FSB speed Real World Scenario Choosing the Right Memory for Your CPU Let s say you head down to your local computer store where motherboards CPUs memory and other computer components are sold a la carte You re interested in putting together your own system from scratch Usually you will have a CPU in mind that you would like to use in your new system Assuming you choose for example an Intel Core 2 Quad 08200 processor you discover you need a motherboard that has an LGA 775 socket and supports a frontside bus of 1333MHz You could assume you need DDR3 memory because DDR2 tops out around 1066MHz PC2 8500 If you d rather not assume you can consult the chosen moth
42. ell as a PS 2 mouse connector right above it on the motherboard Compare your PC s keyboard connector with Figures 1 17 and 1 18 FIGURE 1 17 An AT connector on a motherboard FIGURE 1 18 A PS 2 style keyboard connector on a motherboard Wireless keyboard and mouse attachment is fairly popular today and is most often achieved with Bluetooth technology or a proprietary RF implementation 28 Chapter 1 Personal Computer System Components P Newer motherboards have color coded the PS 2 mouse and keyboard con A nectors to make connection of keyboards and mice easier PS 2 mouse connectors are green to match the standard green connectors on some mice and the keyboard connectors are purple Peripheral Ports and Connectors In order for a computer to be useful and have the most functionality there must be a way to get the data into and out of it Many different ports are available for this purpose We will discuss the different types of ports and how they work later in this chapter Briefly the seven most common types of ports you will see on a computer are serial par allel Universal Serial Bus USB video see Chapter 3 Ethernet sound in out and game ports Figure 1 19 shows some of these and others on a docking station or port replicator for a laptop From left to right the interfaces shown are as follows DC power in Analog modem RJ 11 Ethernet NIC RJ 45 S video out DVI D dual link out VGA out
43. enhanced performance which can be downward compatible with the 40 wire technology but at reduced performance 26 Chapter 1 Personal Computer System Components The 40 pin ATA header transfers data between the drive and motherboard multiple bits in parallel hence the name Parallel ATA SATA in comparison which came out later and prompted the retroactive PATA moniker transfers data in serial allowing a higher data throughput because there is no need for more advanced parallel synchronization of data sig nals The SATA headers are vastly different from the PATA headers Figure 1 16 shows an example of the SATA data connector FIGURE 1 16 The Serial ATA connector Keyboard Connectors The most important input device for a PC is the keyboard All PC motherboards contain a connector that allows a keyboard to be connected directly to the motherboard through the case There are two main types of wired keyboard connectors Once these were the AT and PS 2 connectors Today the PS 2 style connector remains popular but it is quickly being replaced by USB attached keyboards The all but extinct original AT connector is round Identifying Components of Motherboards 27 about inch in diameter in a 5 pin DIN configuration Figure 1 17 shows an example of the AT style keyboard connector The PS 2 connector as shown in Figure 1 18 is a smaller 6 pin mini DIN connector Many new PCs you can purchase today contain a PS 2 keyboard connector as w
44. equired to satisfy the same Pentium processor For those modules that have fewer than eight or nine chips mounted on them more than one bit for every byte is being handled by some of the chips For example if you see three chips mounted the two larger chips probably handle 4 bits a nybble from each byte stored and the third smaller chip probably handles the single parity bit for each byte Even and odd parity schemes operate on each byte in the set of memory chips In each case the number of bits set to a value of 1 is counted up If there are an even number of 1 bits in the byte 0 2 4 6 or 8 even parity stores a 0 in the ninth bit the parity bit otherwise it stores a 1 to even up the count Odd parity does just the opposite storing a 1 in the parity bit to make an even number of 1s odd and a 0 to keep an odd number of 1s odd You can see that this is effective only for determining if there was a blatant error in the set of bits received but there is no indication as to where the error is and how to fix it Furthermore the total 1 bit count is not important only whether it s even or odd Therefore in either the even or odd scheme if an even number of bits is altered in the same byte during transmission the error goes undetected because flipping 2 4 6 or all 8 bits results in an even number of 1s remaining even and an odd number of 1s remaining odd Mark and space parity are used in systems that want to see 9 bits for every byte
45. er in lieu of requiring a device driver to do so The BIOS chip is easily identified if you have a non clone computer this chip might have on it the name of the manufacturer and usually the word BIOS For clones the chip usually has a sticker or printing on it from one of the major BIOS manufacturers AMI Phoenix Award Winbond and so on On later motherboards the BIOS might be difficult to identify but the functionality remains regardless of how it s implemented Figure 1 24 gives you an idea of what a modern BIOS might look like Despite the 1998 copyright on the label this particular chip can be found on motherboards produced as late as 2009 Notice also the Reset CMOS jumper at lower left and its configuration silkscreen at upper left You might use this jumper to clear the CMOS memory discussed next when an unknown password for example is keeping you out of the BIOS configuration utility The jumper in the photo is in the clear position not the normal operating position System bootup is typically not possible in this state FIGURE 1 24 A BIOS chip ona motherboard ko 208 RIF3 RIF4 A major function of the BIOS is to perform a process known as power on self test POST POST is a series of system checks performed by the system BIOS and other high end components such as the SCSI BIOS and the video BIOS Among other things the POST routine verifies the integrity of the BIOS itself It also verifies and confirms the size of p
46. er automatically detected or set manually in the BIOS setup program Firmware Firmware is the name given to any software that is encoded in hardware usually a read only memory ROM chip and can be run without extra instructions from the operating system Most computers and large printers use firmware in some sense The best example of firmware is a computer s BIOS routine which is burned in to a chip Also some expansion cards such as small computer system interface SCSI cards and graphics adapters use their own firmware utilities for setting up peripherals 34 Chapter 1 Personal Computer System Components Identifying Purposes and Characteristics of Processors Now that you ve learned the basics of the motherboard you need to learn about the most important component on the motherboard the CPU The role of the CPU or central pro cessing unit is to control and direct all the activities of the computer using both external and internal buses It is a processor chip consisting of an array of millions of transistors Intel and Advanced Micro Devices AMD are the two largest PC compatible CPU manu facturers Their chips were featured earlier in Table 1 1 during the discussion of the sockets and slots in which they fit ex The term chip has grown to describe the entire package that a technician Qo might install in a socket However the word originally denoted the silicon wafer that is generally hidden within the carrier th
47. erboard s documentation or display slick and confirm your suspicions If you re right you ll be buying at least one stick of your favorite capacity of PC3 10666 multiplying 1333 by 8 two sticks if you need to feed a hungry dual channel motherboard In case you missed it PC3 10666 modules are made using DDR3 1333 chips so named for the speed of the FSB Recall the 8 1 module to chip FSB naming convention DRDRAM Direct Rambus DRAM DRDRAM named for Rambus the company that designed it is a proprietary SDRAM technology sometimes called RDRAM dropping direct DRDRAM can be found in fewer new systems today than just a few years ago This is because Intel once had a contractual agreement with Rambus to create chipsets for the motherboards of Intel and others that would primarily use DRDRAM in exchange for 48 Chapter 1 Personal Computer System Components special licensing considerations and royalties from Rambus The contract ran from 1996 until 2002 In 1999 Intel launched the first motherboards with DRDRAM support Until then Rambus could be found mainly in gaming consoles and home theater components DRDRAM did not impact the market as Intel had hoped and so motherboard manufactur ers got around Intel s obligation by using chipsets from VIA Technologies leading to the rise of that company Although other specifications preceded it the first motherboard DRDRAM model was known as PC800 As with non DRDRAM specifications t
48. erboards Know the components of a motherboard Be able to describe motherboard components such as chipsets expansion slots memory slots and external cache CPU and processor slots or sockets power connectors onboard disk drive connectors keyboard connectors peripheral ports and connectors BIOS firmware chips CMOS batteries jumpers and DIP switches Understand the purposes and characteristics of processors Be able to discuss the different processor packaging old and new and know the meaning of the terms hyperthreading multi core throttling microcode overclocking cache speed and system bus width Understand the purposes and characteristics of memory Know about the characteristics that set the various types of memory apart from one another This includes the actual types of memory such as DRAM which includes several varieties SRAM ROM and CMOS as well as memory packaging such as SIMMs DIMMs RIMMs SODIMMS and MicroDIMMs Also have a firm understanding of the different levels of cache memory as well as its purpose in general Understand the purposes and characteristics of adapter cards and their ports and cables Familiarize yourself with the variety of expansion cards and integrated components in today s computer systems as well as the ports they use and any cables that connect to external devices Understand the purposes and characteristics of cooling systems Know the different ways that internal components
49. erfaces It is most often found on peripherals not on computers themselves except in the case of some older SCSI interface cards FIGURE 1 44 A Centronics connector Common Peripheral Interfaces and Cables An interface is a method of connecting two dissimilar items together A peripheral interface is a method of connecting a peripheral or accessory to a computer including the specifica tion of cabling connector and port type speed and method of communication used The most common interfaces used in PCs today include Parallel Serial USB JEEE 1394 FireWire Infrared RCA PS 2 For each type let s look at the cabling and connector used as well as the type s of peripherals that are connected Identifying Characteristics of Ports and Cables 63 Parallel For many years the most popular type of interface available on computers was the parallel interface Parallel communications take the interstate approach to data communications Normally interstate travel is faster than driving on city roads This is the case mainly because you can fit multiple cars going the same direction on the same highway by using multiple lanes On the return trip you take a similar path but on a completely separate road The parallel interface an example is shown at the top of Figure 1 36 transfers data 8 bits at a time over eight separate transmit wires inside a parallel cable one bit per wire Normal parallel interfaces us
50. ertion Force VLIF principle To see which socket type is used for which processors examine Table 1 1 FIGURE 1 14 A Slot 1 connection slot TABLE 1 1 Socket Slot Types and the Processors They Support Socket Slot Processors Slot 1 Pentium II Pentium Ill Celeron and all SECC and SECC2 Slot 2 Pentium II Xeon Pentium Ill Xeon server replaced by Socket 370 Slot A Early AMD Athlon physically the same as Slot 1 but not electrically replaced by Socket A Sockets 1 2 3 6 486 and Pentium OverDrive TABLE 1 1 Socket Slot Socket 4 Socket 5 Socket 7 Super Socket 7 Socket 8 Socket 370 Socket 423 Socket A Socket 462 Socket 478 Socket 479 Socket 563 Socket 603 Socket 604 Socket 754 Socket P Socket T LGA 775 Socket J LGA 771 Socket B LGA 1366 Socket 939 Socket 940 Identifying Components of Motherboards 23 Socket Slot Types and the Processors They Support continued Processors Pentium 60 66 Pentium 60 66 OverDrive Pentium 75 133 Pentium 75 OverDrive AMD K5 Pentium 75 200 Pentium 75 OverDrive Pentium MMX AMD K6 AMD K6 2 K6 III Oddly combined SPGA PGA format for Pentium Pro replaced by Slot 1 with the introduction of Pentium II Plastic PGA PPGA processors including Pentium III and Celeron Early Pentium 4 AMD Athlon Athlon XP Athlon XP M Athlon MP Thunderbird Duron Sempron Pentium 4 Pentium 4 Extreme Edition Celeron Laptop Pentium M Celeron M AMD
51. es today is the star topology which uses a central concentrating device that is cabled directly to the endpoints A tree structure is formed when these concentrating devices are interconnected to one another each attached to their own set of endpoints One or few concentrators appear at the first tier of the tree sort of like the root system of the tree These root devices are expected to carry more traffic than other concentrators because of their position in the hierarchy In subsequent tiers other concentrators branch off from the root and each other to complete the tree analogy The 1995 IEEE 1394 specification that is equivalent to FireWire 400 allows 1 023 buses each supporting 63 devices to be bridged together This networkable architecture supports over 64 000 interconnected devices that can communicate directly with one another instead of communicating through a host computer the way USB is required to do Star and tree topologies can be formed as long as no two devices are separated by more than 16 hops A hop can be thought of as a link between any two end devices repeaters or bridges result ing in a total maximum distance between devices of 72 meters Through an internal hub a single end device can use two IEEE 1394 ports to connect to two different devices creating a daisy chained pathway that allows the other two devices to communicate with one another as well The device in the middle affords a physical pathway between the ot
52. f memory Dynamic RAM chips are cheaper to manufacture than most other types because they are less complex Dynamic refers to the memory chips need for a constant update signal also called a refresh signal in order to keep the information that is written there If this signal is not received every so often the information will bleed off and cease to exist Currently the most popular implementations of DRAM are based on syn chronous DRAM and include SDR SDRAM DDR DDR2 DDR3 and DRDRAM Before discussing these technologies let s take a quick look at the all but defunct asynchronous memory types Asynchronous DRAM Asynchronous DRAM is characterized by its independence from the CPU s external clock Asynchronous DRAM chips have codes on them that end in a numerical value that is related to often one tenth of the actual value the access time of the memory Access 44 Chapter 1 Personal Computer System Components time is essentially the difference between the time when the information is requested from memory and the time when the data is returned Common access times attributed to asynchronous DRAM were in the 40 to 120 nanosecond ns vicinity A lower access time is obviously better for overall performance Because asynchronous DRAM is not synchronized to the frontside bus you would often have to insert wait states through the BIOS setup for a faster CPU to be able to use such memory These wait states represented intervals that t
53. f the AMR slot but the other portion of the CNR slot is longer than that of the AMR slot Essentially these 60 pin slots allow a motherboard manufacturer to implement a motherboard chipset with certain integrated features Then if the built in features of that chipset need to be enhanced by adding Dolby Digital Surround to a standard sound chipset for example a CNR riser card could be added to enhance the onboard capabilities Additional advantages of CNR over AMR include networking sup port Plug and Play compatibility support for hardware acceleration as opposed to CPU control only and the fact that there s no need to lose a competing PCI slot unless the CNR slot is in use Figure 1 10 shows an example of a CNR slot arrow FIGURE 1 9 AnAMR slot peneceatids 2 Memory Slots and Cache Memory or random access memory RAM slots are the next most prolific slots on a motherboard and they contain the modules that hold memory chips that make up primary memory the memory used to store currently used data and instructions for the CPU Many and varied types of memory are available for PCs today In this chapter you will become familiar with the appearance and specifications of the slots on the motherboard so you can identify them For the most part PCs today use memory chips arranged on a small circuit board Certain of these circuit boards are called dual inline memory modules DIMMs Today s DIMMs differ in the numbe
54. form of foam silicone adhesive and greaseless non curing adhesives are available to seal the surface and perimeter of the processor Additionally manufacturers sell gaskets and shims that correspond to specific processors all designed to protect your delicate and expensive components from damage Liquid Nitrogen and Helium Cooling In the interest of completeness there is a novel approach to super cooling processors that is ill advised under all but the most extreme circumstances By filling a vessel placed over the component to be cooled with a liquid form of nitrogen or for an even more intense effect helium temperatures from 100 to 240 degrees Celsius can be achieved The results are short lived and only useful in overclocking with a view to setting records The processor is not likely to survive the incident due to the internal stress from the extreme temperature changes Summary In this chapter we took a tour of the system components of a PC You learned about some of the elements that make up a PC You ll learn about others in the next two chapters In addition we discussed common peripheral ports and cables and their appearance Finally you learned about the various methods used for cooling a PC You also saw what many of these items look like and how they function Exam Essentials 79 Exam Essentials Know the types of system boards Know the characteristics of and differences between ATX micro ATX NLX and BTX moth
55. g ging is possible only on open ended slots although not specifically allowed in the official specification Even if you find or make by cutting a groove in the end an open ended slot that accepts a longer card edge the inserted adapter cannot operate faster than the slot s maximum rated capability because the required physical wiring to the PCle switch on the motherboard is not present Because of its high data rate PCle is the current choice of gaming aficionados Addition ally technologies similar to NVIDIA s Scalable Link Interface SLI allow such users to combine preferably identical graphics adapters in neighboring PCle x16 slots with a hard ware bridge to form a single virtual graphics adapter The job of the bridge is to provide non chipset communication among the adapters The bridge is not a requirement for SLI to work but performance suffers without it SLI ready motherboards allow two three or four PCle graphics adapters to pool their graphics processing units GPUs and memory to feed graphics output to a single monitor attached to the adapter acting as SLI master SLI implementation results in increased graphics performance over single PCle and non PCle implementations Figure 1 8 is a photo of an SLI ready motherboard with three PCIe x16 slots every other slot starting with the top one one PCIe x1 slot second slot from the top and two PCI slots first and third slots from the bottom Notice the latch that secures t
56. ged in a square as shown in Figure 1 13 The top socket is known as Socket A or Socket 462 and has holes to receive the pins on the CPU The bottom socket is known as Socket T or Socket LGA 775 and has spring loaded pins in the socket and a grid of lands on the CPU The land grid array LGA is a newer technology that places the delicate pins on the cheaper moth erboard not the more expensive CPU opposite to the way the aging pin grid array PGA does The device with the pins has to be replaced if the pins become too damaged to func tion PGA and LGA are mentioned again later in this chapter in the section Identifying Purposes and Characteristics of Processors Modern CPU sockets have some sort of mechanism in place that reduces the need to apply the considerable force to the CPU that was necessary in the early days of personal computing to install a processor Given the extra surface area on today s processors exces sive pressure applied in the wrong manner could damage the CPU packaging its pins or the motherboard itself For CPUs based on the PGA concept zero insertion force ZIF sockets are exceedingly popular ZIF sockets use a plastic or metal lever on one edge to lock or release the mechanism that secures the CPU s pins in the socket The CPU rides on the mobile top portion of the socket and the socket s contacts that mate with the CPU s pins are in the fixed bottom portion of the socket The Socket 462 image in Figure 1 13
57. gh the body of the heat sink to force the heat into the ambient internal air where it can join the airflow circuit for removal from the case However the latest trend in support of high end processors is a redesign of the classic heat sink The heat sink extends up farther using radiator type fins and the fan is placed at a right angle and to the side of the heat sink This design moves the heat away from the heat sink imme diately instead of pushing the air down through the heat sink CPU fans can be purchased that have an adjustable rheostat to allow you to dial in as little airflow as you need aiding in noise reduction but potentially leading to accidental overheating It should be noted that the highest performing CPU coolers use copper plates in direct contact with the CPU They also use high speed and high CFM cooling fans to dissipate the heat produced by the processor CFM is short for cubic feet per minute an airflow measurement of the volume of air that passes by a stationary object per minute Most new CPU heat sinks use tubing to transfer heat away from the CPU With any cooling system the more surface area exposed to the cooling method the better the cool ing Plus the heat pipes can be used to transfer heat to a location away from the heat source before cooling This is especially useful in small form factor cases and laptops where open space is limited With advanced heat sinks and CPU cooling methods like this it is important
58. hat use this nam ing convention PC800 specifies that using a faster 400MHz actual clock signal and double pumping like DDR SDRAM an effective frequency and FSB speed of 800MHz is created DRDRAM was originally named in a dissimilar fashion to other forms of SDRAM instead based on the FSB speed You might recall for those memory types that the FSB speed was used to name the actual chips on the modules not the modules themselves PC800 DRDRAM then features a double pumped 800MHz FSB Newer modules such as the 32 bit RIMM 6400 are named for their actual throughput 6400MBps in this case The section RIMM in this chapter details the physical details of the modules There are only 16 data pins per channel with DRDRAM versus 64 bits per channel in other SDRAM implementations This fact results in a 16 bit 2 byte channel A 2 byte packet therefore is exchanged during each read write cycle bringing the overall transfer rate of PC800 DRDRAM to 1600MBps per channel DRDRAM chipsets require two 16 bit channels to communicate simultaneously for the same read write request creating a mandatory 32 bit dual channel mode Two PC800 DRDRAM modules in a dual channel configuration produce transfer rates of 3200MBps In motherboards that support 32 bit modules you would use a single RIMM 3200 to achieve this 3200MBps of throughput using the same actual 400MHz clock and 800MHz FSB and transferring 4 bytes at a time Despite DRDRAM s performance a
59. he CPU had to mark time and do nothing while waiting for the memory subsystem to become ready again for subse quent access Common asynchronous DRAM technologies included Fast Page Mode FPM Extended Data Out EDO and Burst EDO BEDO Feel free to investigate the details of these par ticular technologies but a thorough discussion of these memory types is not necessary here The A technician should be concerned with synchronous forms of RAM which are the only types of memory being installed in mainstream computer systems today Synchronous DRAM Synchronous DRAM SDRAM shares a common clock signal with the computer s sys tem bus clock which provides the common signal that all local bus components use for each step that they perform This characteristic ties SDRAM to the speed of the FSB and hence the processor eliminating the need to configure the CPU to wait for the memory to catch up Originally SDRAM was the term used to refer to the only form of synchronous DRAM on the market As the technology progressed and more was being done with each clock signal on the FSB various forms of SDRAM were developed What was once called sim ply SDRAM needed a new name retroactively Today we use the term single data rate SDRAM SDR SDRAM to refer to this original type of SDRAM SDR SDRAM With SDR SDRAM every time the system clock ticks one bit of data can be transmitted per data pin limiting the bit rate per pin of SDRAM to the corre
60. he x16 adapters in place Any movement of these high performance devices can result in temporary failure or poor performance 16 Chapter 1 Personal Computer System Components FIGURE 1 8 PCle expansion slots gt Sa Erci slor 2 AMR Expansion Slots As is always the case Intel and other manufacturers are constantly looking for ways to improve the production process One lengthy process that would often slow down the pro duction of motherboards with integrated analog I O functions was FCC certification The manufacturers developed a way of separating the analog circuitry for example modem and analog audio onto its own card This allowed the analog circuitry to be separately certified it was its own expansion card thus reducing time for FCC certification This slot and riser card technology was known as the Audio Modem Riser AMR AMR s 46 pin slots were once fairly common on many Intel motherboards but technologies including CNR and Advanced Communications Riser ACR are edging out AMR In addi tion and despite FCC concerns integrated components still appear to be enjoying the most success comparatively Figure 1 9 shows an example of an AMR slot CNR Expansion Slots The Communications and Networking Riser CNR slots that can be found on some Intel motherboards are a replacement for Intel s AMR slots One portion of these slots is the Identifying Components of Motherboards 17 same length as one of the portions o
61. her two devices but is not otherwise involved in their communication with one another RCA The RCA cable is simple There are two connectors usually male one on each end of the cable The male connector connects to the female connector on the equipment Figure 1 53 shows an example of an RCA cable An RCA male to RCA female connector is also avail able it s used to extend the reach of audio or video signals Identifying Characteristics of Ports and Cables 71 FIGURE 1 53 An RCA cable The RCA male connectors on a connection cable are sometimes plated in gold to increase their corrosion resistance and to improve longevity PS 2 Keyboard and Mouse The final interface we ll discuss is the PS 2 interface for mice and keyboards Essentially it is the same connector for the cables from both items a male mini DIN 6 connector Most keyboards today still use the PS 2 interface whereas most mice are gravitating toward the USB interface especially optical mice However mice that have USB cables still may include a special USB to PS 2 adapter so they can be used with the PS 2 interface Figure 1 54 shows an example of a PS 2 keyboard cable FIGURE 1 54 A PS 2 keyboard cable Most often PS 2 cables have only one connector because the other end TE is connected directly to the device being plugged in The only exception is PS 2 extension cables used to extend the length of a PS 2 device s cable 72 Chapter 1 Personal Compute
62. id to late 2004 When that time came the new BTX motherboard was met with mixed reactions Let s postpone accusations of acronym reverse engineering until CTX is announced as the name of the next generation Intel and its consumers realized that the price for faster components that produced more heat would be a retooling of the now classic since mid 1990s ATX design The motherboard manufacturers saw research and development expense and potential profit loss simply to accommodate the next generation of hotter running processors processors manufactured by the same designers of the BTX technology It was this resistance that caused the BTX form factor to gain very little ground over the next couple of years Nevertheless with the early support of Gateway and later buy in of Dell the BTX design dug in and charted a path for future success Marketing aside the BTX technology is well thought out and serves the purpose for which it was intended By lining up all heat producing components between air intake vents and the power supply s exhaust fan Intel found that the CPU and other components could be cooled properly by passive heat sinks A heat sink is a block of aluminum or other metal with veins throughout that sits on top of the CPU drawing its heat away Fewer fans and a more efficient airflow path create a quieter configuration overall While the BTX design benefits any modern onboard implementation Intel s recommitment to lower p
63. ion Identifying Purposes and Characteristics of Power Sup plies plugs in Onboard Floppy and Hard Disk Connectors Almost every computer made today uses some type of disk drive to store data and pro grams until they are needed All drives need some form of connection to the motherboard so the computer can talk to the disk drive Regardless of whether the connection is built into the motherboard onboard it could reside on an adapter card off board the standard for the attachment is based on the drive s requirements These connections are known as drive interfaces and there are two main types floppy drive interfaces and hard disk drive interfaces Floppy drive interfaces allow floppy disk drives FDDs to be con nected to the motherboard and similarly hard disk drive interfaces do the same for hard disks and optical drives among others The interfaces consist of circuitry and a port or header Most motherboards produced today include both the floppy disk and non SCSI hard disk interfaces on the motherboard Server motherboards often include SCSI headers and circuitry instead Identifying Components of Motherboards 25 FIGURE 1 15 An ATX power connector on a motherboard a Today the headers you will find on most motherboards are for Enhanced IDE EIDE also known retroactively as Parallel ATA PATA or Serial ATA SATA Advanced Tech nology Attachment ATA is the standard term for what is more commonl
64. ion of where the cache is located The terms L1 cache and L3 cache do not vary in their meaning however The typical increasing order of capacity and dis tance from the processor die is L1 cache L2 cache L3 cache RAM This is also the typical decreasing order of speed Central Processing Unit CPU and Processor Socket or Slot The brain of any computer is the central processing unit CPU There s no computer without the CPU There are many different types of processors for computers so many in fact that you will learn about them later in this chapter in the section Identifying Pur poses and Characteristics of Processors Typically in today s computers the processor is the easiest component to identify on the motherboard It is usually the component that has either a fan or a heat sink usually both 20 Chapter 1 Personal Computer System Components attached to it as shown in Figure 1 12 These devices are used to draw away and disperse the heat a processor generates This is done because heat is the enemy of microelectronics Theo retically a Pentium or higher processor generates enough heat that without the heat sink it would permanently damage itself and the motherboard in a matter of hours or even minutes FIGURE 1 12 Two heat sinks one with a fan Sockets and slots on the motherboard are almost as plentiful and varied as processors Sockets are basically flat and have several rows of holes or pins arran
65. it errors In this section we ll outline the major types of computer memory as well as the methods of implementing or packaging such memory Identifying Purposes and Characteristics of Memory 41 Single and Double Sided Memory Ask just about anyone who doesn t manufacture memory for a living what the terms single sided memory and double sided memory mean and you ll be treated to a blank stare or a short diatribe on how some memory modules have chips on one side while others have chips on both sides In fact these terms have nothing to do with the physical attachment of chips to the modules Either style can have chips on one or both sides of the module Double sided memory is essentially treated by the system as two separate memory modules Motherboards that support such memory have memory controllers that must switch between the two sides of the modules and at any particular moment can only access the side they have switched to For the state of the art memory at the time double sided memory allows more memory to be inserted into a computer using half the physical space of single sided memory which requires no switching by the memory controller Single and Dual Channel Memory Standard memory controllers manage access to memory in chunks of the same size as the FSB s data width This is considered communicating over a single channel Most modern processors have a 64 bit system data bus This means a standard memory contro
66. ive configuration Memory Integrated ports Boot sequence Power management Your PC keeps these settings in a special memory chip called the complementary metal oxide semiconductor CMOS memory chip Actually CMOS usually pronounced see moss is a manufacturing technology for integrated circuits The first commonly used chip made from CMOS technology was a type of memory chip the memory for the BIOS As a result the term CMOS is the accepted name for this memory chip The BIOS starts with its own default information and then reads information from the CMOS such as which hard drive types are configured for this computer to use which drive s it should search for boot sectors and so on Any overlapping information read from the CMOS overrides the default information from the BIOS A lack of corresponding information in the CMOS does not delete information that the BIOS knows natively This process is a merge not a write over CMOS memory is usually not upgradable in terms of its capacity and might be integrated into the BIOS chip or some other chip To keep its settings integrated circuit based memory must have power constantly When you shut off a computer anything that is left in this type of memory is lost forever The CMOS manufacturing technology produces chips with very low power requirements One ramification of this fact is that today s electronic circuitry is more susceptible to damage Identifying Components of Motherboar
67. le the industry has settled on the practice of using this effective clock rate as the speed of the FSB Module Throughput Related to FSB Speed There is always an 8 1 module to chip or module to FSB speed numbering ratio because of the 8 bytes that are transferred at a time with 64 bit processors The following formula explains how this relationship works FSB in MHz cyetes second X 8 bytes bytes cyete throughput bytes second Because the actual clock speed is rarely mentioned in marketing literature on packag ing or on store shelves for DDR and higher you can use this advertised FSB frequency in your computations for DDR throughput For example with a 100MHz clock and two operations per cycle motherboard makers will market their boards as having an FSB of 200MHz Multiplying this effective rate by 8 bytes transferred per cycle the data rate is 1600MBps Now that throughput is becoming a bit trickier to compute the industry uses this final throughput figure to name the memory modules instead of the actual fre quency which was used when naming SDR modules This makes the result seem many times better and much more marketable while it s really only twice or so as good or close to it In this example the module is referred to as PC1600 based on a throughput of 1600MBps The chips that go into making PC1600 modules are named DDR200 for the effective FSB fre quency of 200MHz Stated differently th
68. le processors appear to the operating system to be two processors As a result the operating system can schedule two processes at the same time as in the case of symmet ric multiprocessing SMP where two or more processors use the same system resources In fact the operating system must support SMP in order to take advantage of HTT If the cur rent process stalls because of missing data caused by say cache or branch prediction issues the execution resources of the processor can be reallocated for a different process that is ready to go reducing processor downtime 36 Chapter 1 Personal Computer System Components Real World Scenario Which CPU Do You Have The surest way to determine which CPU your computer is using is to open the case and view the numbers stamped on the CPU which today requires removal of the active heat sink However you may be able to get an idea without opening the case and removing the heat sink and fan because many manufacturers indicate the type of processor by placing a very obvious sticker somewhere on the case indicating the processor type Failing this you can always go to the manufacturer s website and look up the information on the model of computer you have If you have a no name clone there is always the System Properties pages found by right clicking My Computer Computer in Windows Vista and selecting Properties The Gen eral tab which is the default contains such information Even m
69. led PC2 5300 for the same marketability mentioned earlier They both support 5333MBps of throughput DDR3 SDRAM The next generation of memory devices was designed to roughly double the performance of DDR2 products Based on the functionality and characteristics of DDR2 s proposed successor most informed consumers and some members of the industry surely assumed the forthcoming name would be DDR4 This was not to be however and DDR3 was born This naming convention proved that the 2 in DDR2 was not meant to be a multi plier but instead a revision mark of sorts Well if DDR2 was the second version of DDR then DDR3 is the third DDR3 is a memory type that was designed to be twice as fast as the DDR2 memory that operates with the same FSB speed Just as DDR2 was required to lower power consumption to make up for higher frequencies DDR3 must do the same In fact the peak voltage for DDR3 is only 1 5V Identifying Purposes and Characteristics of Memory 47 The most commonly found range of actual clock speeds for DDR3 tends to be from 133MHz at the low end to 250MHz Because double pumping continues with DDR3 and because four operations occur at each wave crest 8 operations per cycle this frequency range translates to common FSB implementations from 1066MHz to 2000MHz in DDR3 systems Naming these memory devices follows the conventions established earlier There fore if you buy a motherboard with a 1600MHz FSB you know immediately that you ne
70. lel Ports As more people began using parallel ports to interface with devices other than printers they started to notice that the available speed wasn t good enough Double speed CD ROM drives had a transfer rate of 300KBps but the parallel port could transfer data at only 150KBps thus limiting the speed at which a computer could retrieve data from an external device To solve that problem the Institute of Electrical and Electronics Engineers IEEE came up with a standard for enhanced parallel ports called IEEE 1284 The IEEE 1284 standard provides for greater data transfer speeds and the ability to send memory addresses as well as data through a parallel port This standard allows the parallel port to theoreti cally act as an extension to the main bus In addition these ports are backward compatible 64 Chapter 1 Personal Computer System Components with the standard and bidirectional ports and support cable lengths of 4 5 meters which is almost 15 feet There are two implementations of IEEE 1284 EPP parallel ports and ECP parallel ports An enhanced parallel port EPP increases bidirectional throughput from 150KBps to any where from 600KBps to 1 5MBps An enhanced capabilities port ECP is designed to trans fer data at even higher speeds around 2MBps ECP uses direct memory access DMA and buffering to increase printing performance over EPP The cable must also have full support for IEEE 1284 in order for proper P communications
71. ll as from the chipset Water is circulated through this block to a radiator where it is cooled The theory is that you could achieve better cooling performance through the use of liquid cooling For the most part this is true However with traditional cooling methods which use air and water the lowest temperature you can achieve is room temperature Plus with liquid cooling the pump is submerged in the coolant generally speaking so as it works it produces heat which adds to the overall liquid temperature The main benefit to liquid cooling is silence There is only one fan needed the fan on the radiator to cool the water So a liquid cooled system can run extremely quietly Liquid cooling while more efficient than air cooling and much quieter has its drawbacks Most liquid cooling systems are more expensive than supplemental fan sets and require less familiar components such as reservoir pump water block s hose and radiator The relative complexity of installing liquid cooling systems coupled with the perceived danger of liquids in close proximity to electronics leads most computer owners to consider liquid cooling a novelty or a liability The primary market for liquid cooling is the high performance niche that engages in overclocking to some degree However developments in active air cooling including extensive piping of heat away from the body of the heat sink have kept advanced cooling methods out of the forefront He
72. ller can transfer exactly 64 bits of information at a time Communicating over a single channel is a bottleneck in an environment where the CPU and memory can both operate faster than the conduit between them Up to a point every channel added in parallel between the CPU and RAM serves to ease this constriction Memory controllers that support or require dual channel memory implementation were developed in an effort to alleviate the bottleneck between the CPU and RAM Dual channel memory is the memory controller s coordination of two memory banks to work as a synchro nized set during communication with the CPU doubling the specified system bus width from the memory s perspective Because today s processors largely have 64 bit external data buses and because one stick of memory satisfies this bus width there is a 1 1 ratio between banks and modules This means that implementing dual channel memory in today s most popular computer systems generally requires that pairs of memory modules be installed at a time Note however that it s the motherboard not the memory that implements dual channel memory more on this in a moment Single channel memory in contrast is the classic mem ory model that dictates only that a complete bank be satisfied whenever memory is initially installed or added One bank supplies only half the width of the effective bus created by dual channel support which by definition pairs two banks at a time Because of
73. mall RAM form factor In fact it is over 50 percent smaller than a SODIMM only 45 5 millimeters about 1 75 inches long and 30 millimeters about 1 2 inches a bit bigger than a quarter wide It was designed for the ultralight and portable subnotebook style of computer These modules have 144 pins or 172 pins and are similar to a DIMM in that they use a 64 bit data bus Often employed in laptop computers SODIMMs and MicroDIMMs are mentioned in Chapter 4 as well 54 Chapter 1 Personal Computer System Components FIGURE 1 34 144 pin SODIMM Identifying Characteristics of Ports and Cables Now that you ve learned the various types of items found in a computer let s discuss the various types of ports and cables used with computers A port is a generic name for any connector on a computer into which a cable can be plugged A cable is simply a way of connecting a peripheral or other device to a computer using multiple copper or fiber optic conductors inside a common wrapping or sheath Typically cables connect two ports one on the computer and one on some other device Let s take a quick look at some of the different styles of port connector types as well as peripheral port and cable types We ll begin by looking at peripheral port connector types Identifying Characteristics of Ports and Cables 55 Peripheral Port Connector Types Computer ports are interfaces that allow other devices to be connected to a computer Their appeara
74. n one wire and they return on a differ ent wire in the same cable Three main types of serial interfaces are available today standard serial Universal Serial Bus USB and FireWire USB and FireWire use increased signaling frequencies to overcome serial s stigma and join other serial technologies such as PCle and SATA as frontrunners in data communications Standard Serial Almost every computer made since the original IBM PC has at least one serial port These computers are easily identified because they have either a DE 9 male or a DB 25 male port shown in Figure 1 47 Standard serial ports have a maximum data transmission speed of 57Kbps and a maximum cable length of 50 feet Serial cables come in two common wiring configurations standard serial cable and null modem serial cable A standard serial cable is used to hook various peripherals such as modems and printers to a computer A null modem serial cable is used to hook two computers together without a modem The transmit wires on one end are wired to the receive pins on the other side so it s as if a modem connection exists between the two computers but with out the need for a modem Figures 1 48 and 1 49 show the wiring differences the pinouts between a standard serial cable and a null modem cable In the null modem diagram notice how the transmit tx pins on one end are wired to the receive rx pins on the other 66 Chapter 1 Personal Computer System Components FIGURE
75. n the right Notice the size difference As you can see RJ connectors are typically square with multiple gold contacts on the flat side A small locking tab on the other side prevents the connector and cable from falling or being pulled out of the jack accidentally Other Types of Ports A few other ports are used with computers today These ports include the following Universal Serial Bus USB JEEE 1394 FireWire Infrared Identifying Characteristics of Ports and Cables 57 Audio jacks PS 2 mini DIN a Centronics Let s look at each one and how it is used FIGURE 1 37 RJ ports Universal Serial Bus USB Most computers built after 1997 have one or more flat ports in place of one DE9M serial port These ports are Universal Serial Bus USB ports and they are used for con necting multiple up to 127 peripherals to one computer through a single port and the use of multiport peripheral bubs USB version 1 1 supported data rates as high as 12 Mbps 1 5MBps USB 2 0 supports data rates as high as 480Mbps 60MBps 40 times that of its predecessor Figure 1 38 shows an example of a set of Type A USB ports Port types are explained in the Common Peripheral Interfaces and Cables section later in this chapter USB 2 0 uses the same physical connection as the original USB but it is TE much higher in transfer rates and requires a cable with more shielding that is less susceptible to noise You can tell if a com
76. n you have questions about supported memory Most manufacturers require that slower or single sided memory be inserted in lower numbered memory slots than faster or double sided memory This is because such a system adapts to the first module it sees looking at the lower numbered slots first Counterintuitively however it might be required that you install modules of larger capacity in lower numbered slots than smaller modules Additionally memory technology continues to advance after each generation of mother board chipsets is announced Don t be surprised when you attempt to install a single mod ule of the highest available capacity in your motherboard and the system doesn t recognize the module either by itself or with others That capacity of module might not have been in existence when the motherboard s chipset was released Consult the motherboard s docu mentation One common point of confusion not related to capacity when installing memory includes lack of recognition of four modules when two or three modules work fine for example In such a case let s say your motherboard s memory controller supports a total of four modules Recall that a double sided module acts like two separate modules If you are using double sided memory your motherboard might limit you to two such modules comprising four sides essentially four virtual modules even though you have four slots on the board If instead you start with three single
77. nce varies widely depending on their function In this section we ll examine the fol lowing types of peripheral ports D subminiature RJ series Other types D subminiature Connectors D sub connectors for a number of years the most common style of connector found on computers are typically designated with DXn where the letter X is replaced by the let ters A through E which refer to the size of the connector and the letter n is replaced by the number of pins or sockets in the connector D sub connectors are usually shaped like a trapezoid as you can see in Figure 1 36 The nice part about these connectors is that only one orientation is possible If you try to connect them upside down or try to connect a male connector to another male connector they just won t go together and the connection can t be made Table 1 3 lists common D sub ports and connectors as well as their most common uses Be on the lookout for the casual use of DB to represent any D sub connector This is very common and is accepted as an unwritten de facto standard At the bottom left in Figure 1 36 is a DE15F 15 pin video port in the center is a DB25F 25 pin female printer port and on the right is a DE9M 9 pin male serial port TABLE 1 3 Common D sub Connectors Connector Gender Use DEY Male Serial port DE9 Female Connector on a serial cable DB25 Male Serial port or connector on a parallel cable DB25 Female Parallel port or connector on
78. nd 3 inches long compared to the classic ISA slot and usually white PCI slots can usually be found in any computer that has a Pentium class processor or higher PCI expansion buses operate at 33 or 66MHz over a 32 bit 4 byte channel resulting in data rates of 133 and 266MBps respectively with 133MBps the most common server architectures excluded Servers often feature 64 bit slots as well which double the 32 bit data rates PCI slots and adapters are manufactured in 3 3 and 5V versions Universal adapters are keyed to fit in slots based on either of the two voltages The notch in the card edge of the com mon SV slots and adapters is oriented toward the front of the motherboard and the notch in the 3 3V adapters toward the rear Figure 1 6 shows several PCI expansion slots Note the 5V 32 bit slot in the foreground and the 3 3V 64 bit slots Also notice that a universal 32 bit card fits fine in the 64 bit 3 3V slot FIGURE 1 6 PCI expansion slots AGP Expansion Slots Accelerated Graphics Port AGP slots are known mostly for video card use and are steadily being supplanted by PCI Express adapters In the past if you wanted to use a high speed accelerated 3D graphics video card you had to install the card into an exist ing PCI or ISA slot AGP slots were designed to be a direct connection between the video circuitry and the PC s memory They are also easily recognizable because they are usually brown are located right next to the
79. nformation is already cached either at L1 or L2 If not a cache miss is recorded and the information is brought back from the much slower RAM but this new information sticks to the various levels of cache on its way to the CPU from RAM Speed The speed of the processor is generally described in clock frequency MHz or GHz There can be a discrepancy between the advertised frequency and the frequency the CPU uses to latch data and instructions through the pipeline This disagreement between the numbers comes from the fact that the CPU is capable of splitting the clock signal it receives from the external oscillator that drives the frontside bus into multiple regular sig nals for its own internal use In fact you might be able to purchase a number of processors rated for different internal speeds that are all compatible with a single motherboard that has a frontside bus rated for instance at 800MHz 38 Chapter 1 Personal Computer System Components Matching System Components In a world of clock doubling tripling quadrupling and so forth it becomes increasingly important to pay attention to what you are buying when you purchase CPUs memory and motherboards a la carte The only well known relationship that exists among these components is the speed of the FSB in MHz and the throughput of the memory in MBps Because 8 bytes are transferred in parallel by a processor with a 64 bit 64 bits 8 bytes system data bus you have t
80. not use more than 5 hubs between any two components Through the use of a 7 bit identifier overall no more than 127 devices including hubs should be connected back to a single USB host controller in the computer not that you would ever want to approach this number The 128th identifier is used for broadcasting No intercon nection of host controllers is allowed with USB each one and its connected devices are isolated from other controllers and their devices As a result USB ports are not considered networkable ports Consult your system s documentation to find out if your USB ports operate on the same host controller From the perspective of the cable s plug Type A is always oriented toward the system from the component As a result you might notice that the USB receptacle on the computer system that a component cables back to is the same as the receptacle on the USB hub that components cable back to The USB hub is simply an extension of the system and becomes a component that cables back to the system FIGURE 1 50 USB cables and connectors FIGURE 1 51 AUSB hub Identifying Characteristics of Ports and Cables 69 Type B plugs connect in the direction of the component Therefore you see a Type B interface on the hub as well as on the end devices to allow them to cable back to the system or another hub Although they exist USB cables with both ends of the same type a sort of extension cable are in violation of the USB specifi
81. nsive blank of sorts called a continuity RIMM or C RIMM for its role of keeping electrical continuity in the DRDRAM channel until the signal can terminate on the motherboard Think of it like a fusible link in a string of holiday lights It seems to do nothing but no light works without it However 32 bit modules terminate themselves and do not rely on the motherboard circuitry for termi nation so vacant 32 bit slots require a module known as a continuity and termination RIMM CT RIMM SODIMM Notebook computers and other computers that require much smaller components don t use standard RAM packages such as the SIMM or the DIMM Instead they call for a much smaller memory form factor such as a small outline DIMM SODIMMs are available in many physical implementations including the older 32 bit 72 and 100 pin configura tion and newer 64 bit 144 pin SDR SDRAM 200 pin DDR DDR2 and 204 pin DDR3 configurations All 64 bit modules have a single keying notch The 144 pin module s notch is slightly off center Note that although the 200 pin SODIMMs for DDR and DDR2 have slightly different keying it s not so different that you don t need to pay close attention to differentiate the two They are not however interchangeable Figure 1 34 shows an example of a 144 pin 64 bit module Figure 1 35 is a photo of a 200 pin DDR2 SODIMM MicroDIMM A newer and smaller RAM form factor is the MicroDIMM The MicroDIMM is an extremely s
82. o know the FSB rating before you choose the RAM for any particular modern motherboard For example a FSB of 800MHz requires memory rated at a throughput of 6400MBps 800 million cycles per second x 8 bytes per cycle Matching CPUs with motherboards or CPUs with memory requires consulting the docu mentation or packaging of the components Generally the CPU gets selected first Once you know the CPU you want the motherboard tends to come next You must choose a motherboard that features a slot or socket compatible with your chosen CPU The FSB used on the selected motherboard dictates the RAM you should purchase 32 and 64 bit processors The set of data lines between the CPU and the primary memory of the system can be 32 or 64 bits wide among other widths The wider the bus the more data that can be processed per unit of time and hence the more work that can be performed Internal registers in the CPU might be only 32 bits wide but with a 64 bit system bus two separate pipelines can receive information simultaneously For true 64 bit CPUs which have 64 bit internal registers and can run x64 versions of Microsoft operating systems the exter nal system data bus should be 64 bits wide or some larger multiple thereof Identifying Purposes and Characteristics of Memory More memory more memory I don t have enough memory Today memory is one of the most popular easy and inexpensive ways to upgrade a computer As the computer s
83. oling systems Identifying Components of Motherboards The spine of the computer is the motherboard otherwise known as the system board and less commonly referred to as the planar board This is the olive green or brown circuit board that lines the bottom of the computer It is the most important component in the computer because it connects all the other components of a PC together Figure 1 1 shows a typical PC system board as seen from above All other components are attached to this circuit board On the system board you will find the central processing unit CPU underlying circuitry expansion slots video components random access memory RAM slots and a variety of other chips Identifying Components of Motherboards 5 FIGURE 1 1 Atypical system board E ist ONR ja N harie Types of System Boards There are two major types of system boards Nonintegrated system board Each major assembly is installed in the computer as an expansion card The major assemblies we re talking about are items like the video circuitry disk controllers and accessories Nonintegrated system boards can be easily identified because each expansion slot is usually occupied by one of these components It is difficult to find nonintegrated motherboards these days Many of what would normally be called nonintegrated system boards now incorporate the most commonly used circuitry such as IDE and floppy controllers serial controllers and sound
84. ols gt When we use the term Northbridge we are referring to the set of chips and gr circuits that make up a particular subset of a motherboard s chipset There isn t actually a Northbridge brand of chipset The communications between the CPU and memory occur over what is known as the frontside bus FSB which is just a set of signal pathways between the CPU and main memory The clock signal that drives the FSB is used to drive communications by certain other devices such as AGP and PCI Express slots making them local bus technologies The backside bus BSB if present is a set of signal pathways between the CPU and Level 2 or 3 cache memory The BSB uses the same clock signal that drives the FSB If no backside bus exists cache is placed on the frontside bus with the CPU and main memory The Northbridge is directly connected to the Southbridge discussed next and helps to manage the communications between the Southbridge and the rest of the computer Identifying Components of Motherboards 11 Southbridge The Southbridge subset of the chipset as mentioned earlier is responsible for providing support to the myriad onboard slower peripherals PS 2 Parallel IDE and so on manag ing their communications with the rest of the computer and the resources given to them These components do not need to keep up with the external clock of the CPU and do not represent a bottleneck in the overall performance of the system Any component
85. on the side shown in Figure 1 30 FIGURE 1 30 An SDR dual inline memory module DIMM The DIMM used for DDR memory has a total of 184 pins and a single keying notch while the DIMM used for DDR2 has a total of 240 pins one keying notch and possibly an aluminum cover for both sides called a heat spreader designed like a heat sink to dissipate heat away from the memory chips and prevent overheating The DDR3 DIMM is similar to that of DDR2 It has 240 pins and a single keying notch but the notch is in a different location to avoid cross insertion Not only is the DDR3 DIMM physically incompatible with DDR2 DIMM slots it s also electrically incompatible Figure 1 31 is a photo of a DDR2 module A matched pair of DDR3 modules with heat spreaders suitable for dual channel use in a high end graphics adapter or motherboard is shown in Figure 1 32 FIGURE 1 31 A DDR2 SDRAM module RIMM Assumed to stand for Rambus inline memory module but not really an acronym RIMM is a trademark of Rambus Inc and perhaps a clever play on the acronym DIMM a competing form factor A RIMM is a custom memory module that carries DRDRAM and varies in physical specification based on whether it is a 16 bit or 32 bit module The 16 bit modules have 184 pins and two keying notches while 32 bit mod ules have 232 pins and only one keying notch reminiscent of the trend in SDRAM to DDR evolution Figure 1 33 shows the two sides of a 16 bit RIMM module inclu
86. ore detailed information can be found by running the System Information utility from Tools gt Advanced System Information in the Windows XP Help and Support Center or by entering msinfo32 exe in the Start gt Run dialog box for all modern Microsoft desktop operating systems Another way to determine a computer s CPU is to save your work exit any open programs and restart the computer Watch closely as the computer returns to its normal state You should see a notation that tells you what chip you are using Multicore A processor that exhibits a multicore architecture has multiple completely separate processor dies in the same package The operating system and applications see multiple processors in the same way that they see multiple processors in separate sockets As with HTT the operating system must support SMP to benefit from the separate proces sors In addition SMP is not an enhancement if the applications run on the SMP system are not written for parallel processing Dual core and quad core processors are common specific cases for the multicore technology Don t be confused by Intel s Core 2 labeling The numeric component does not imply there are two cores There was a Core series of 32 bit mobile processors that featured one Solo or two Duo processing cores on a single die silicon wafer The same dual core die was used for both classes of Core CPU The second core was disabled for Core Solo processors The 64 bit Core
87. ow profile case types NLX continues the trend of the technology it succeeded Low Profile Extended LPX placing the expansion slots ISA PCI and so on sideways on a special riser card to use the reduced vertical space optimally Adapter cards or daughter boards that normally plug into expansion slots vertically in ATX motherboards for exam ple plug in parallel to the motherboard so their most demanding dimension does not affect case height Figure 1 2 shows a low profile motherboard with its riser card attached Identifying Components of Motherboards 7 FIGURE 1 2 Both sides of a riser card with daughterboard LPX a technology that lacked formal standardization and whose riser card interfaces varied from vendor to vendor enjoyed great success in the 1990s until the advent of the Pentium II processor and the Accelerated Graphics Port AGP These two technologies placed a spotlight on how inadequate LPX was at cooling and accommodating high pin counts NLX an official standard from Intel IBM and DEC was designed to fix the vari ability and other shortcomings of LPX but NLX never quite caught on the way LPX did Newer technologies such as micro ATX and proprietary solutions have been more success ful and have taken even more market share from NLX 8 Chapter 1 Personal Computer System Components Balanced Technology Extended BTX In 2003 Intel announced its design for a new motherboard slated to hit the market m
88. ower CPUs has at once lessened the need to rush to more expensive BTX systems and given the market a bit more time to assimilate this newer technology There are other motherboard designs but these are the most popular and iQ also the ones that are covered on the exam Some manufacturers such as Compaq and IBM design and manufacture their own motherboards which don t conform to the standards This style of motherboard is known as a motherboard of proprietary design System Board Components Now that you understand the basic types of motherboards and their form factors it s time to look at the components found on the motherboard and their locations relative to each other Figure 1 3 illustrates many of the following components found on a typical motherboard Chipsets Expansion slots and buses Memory slots and external cache CPU and processor slots or sockets Power connectors Onboard disk drive connectors Keyboard connectors Identifying Components of Motherboards 9 Peripheral ports and connectors BIOS CMOS battery Jumpers and DIP switches Firmware In this subsection you will learn about the most used components of a motherboard what they do and where they are located on the motherboard We ll show what each com ponent looks like so you can identify it on most any motherboard you run across Note however that this is just a brief introduction to the internal structures of a computer
89. physical memory to the system thus reducing its reliance on virtual memory More information on virtual memory and its con figuration can be found in Chapter 7 Installing and Configuring Operating Systems When it s not the size of RAM that you need to enhance but its speed you can add cache memory on the CPU side of RAM to take care of this Cache is a very fast form of memory forged from static RAM which is discussed in detail in the Identifying Purposes and Characteristics of Memory section later in this chapter Cache improves system per formance by predicting what the CPU will ask for next and prefetching this information before being asked This paradigm allows the cache to be smaller in size than the RAM itself Only the most recently used data and code or that which is expected to be used next is stored in cache Cache on the motherboard is known as external cache because it is exter nal to the processor also referred to as Level 2 L2 cache Level 1 L1 cache by compari son is internal cache because it is built into the processor s silicon wafer It is now common for chip makers to use extra space in the processor s packaging to bring the L2 cache from the motherboard closer to the CPU When L2 cache is present in the processor s packaging the cache on the motherboard is referred to as Level 3 L3 cache Unfortunately due to the de facto naming of cache levels the term L2 cache alone is not a definitive descript
90. pport as well as its maximum speeds and required pairings The memory slots on a motherboard are designed for particular module form factors or styles In case you run across the older terms dual inline package DIP single inline memory module SIMM and single inline pin package SIPP are obsolete memory packages The most popular form factors for primary memory modules today are DIMM RIMM SODIMM a MicroDIMM Note also that the various CPUs on the market tend to support only one form of physical memory packaging For example the Intel Pentium 4 class of processors is always going to be paired with DIMMs while certain early Intel Xeon processors mated only with RIMMs So in addition to coordinating the speed of the components their form factor is an issue that must be addressed as well DIMM One type of memory package is known as a DIMM As mentioned earlier in this chapter DIMM stands for dual inline memory module DIMMs are 64 bit memory modules that are used as a package for the SDRAM family SDR DDR DDR2 and DDR3 The term dual refers to the fact that unlike their SIMM predecessors DIMMs differentiate the function ality of the pins on one side of the module from the corresponding pins on the other side Identifying Purposes and Characteristics of Memory 51 With 84 pins per side this makes 168 independent pins on each standard SDR module as shown with its two keying notches as well as the last pin labeled 84
91. puter hub or cable sup ports USB 2 0 by looking for the red and blue High Speed USB graphic somewhere on the computer device or cable or on its packaging 58 Chapter 1 Personal Computer System Components FIGURE 1 38 USB ports Because of USB s higher transfer rate flexibility and ease of use most devices that in the past used serial interfaces now come with USB interfaces It s rare to see a newly introduced PC accessory with a standard serial interface cable For example PC cameras used to come as standard serial only interfaces Now you can buy them only with USB interfaces IEEE 1394 FireWire Recently one port has been slowly creeping into the mainstream and is seen more and more often on desktop PCs That port is the IEEE 1394 port shown in Figure 1 39 more commonly known as a FireWire port Its popularity is due to its ease of use and very high 400Mbps transmission rates Originally developed by Apple it was standardized by IEEE in 1995 as IEEE 1394 It is most often used as a way to get digital video into a PC so it can be edited with digital video editing tools FIGURE 1 39 A FireWire port on a PC Identifying Characteristics of Ports and Cables 59 Infrared Increasing numbers of people are getting fed up with being tethered to their computers by cords As a result many computers especially portable computing devices like laptops and PDAs are now using infrared ports to send and receive data
92. r You know that you need to plug the keyboard cable into a PS 2 port Which style of port is the PS 2 A RJ 11 B DE9 C DINS D Mini DIN 6 Which of the following are the numbers of pins that can be found on DIMM modules used in desktop motherboards Choose three A 168 B 180 C 184 D 200 E 204 F 232 G 240 What is the maximum speed of USB 2 0 in Mbps A 1 5 B 12 C 60 D 480 82 13 14 15 16 17 18 Chapter 1 Personal Computer System Components Which of the following standards are specified by IEEE 1284 Choose two A SPP RS 232 EPP ECP FireWire USB mmo What peripheral port type was originally developed by Apple and is currently the optimal interface for digital video transfers A DVD B USB C IEEE 1394 D IEEE 1284 What peripheral port type is expandable using a hub operates at 1 5 MBps and is used to connect various devices from printers to cameras to PCs A DVD 1 0 B USB 1 1 C IEEE 1394 D IEEE 1284 Which peripheral port type was designed to transfer data at high speeds over a D sub interface A DVD B USB C IEEE 1394 D IEEE 1284 Which motherboard form factor places expansion slots on a special riser card and is used in low profile PCs A AT B Baby AT Cc ATX D NLX Which Intel processor type might be mounted on a SECC for motherboard installation A Athlon B 486 C Pentium D Pentium IT Review Questions 83 19
93. r 1 5MBps for USB 1 1 which is the option listed here D IEEE 1284 standard defines the ECP parallel port to use a DMA channel and the buffer to be able to transfer data at high speeds to printers D The NLX form factor places expansion slots on a special riser card and is used in low profile PCs D The unique thing about the Pentium II is that it was attached to a single edge contact cartridge SECC for insertion into the motherboard instead of the standard PGA package Athlon is an AMD processor the early version of which was slot based but not considered SECC in any event D Pentium 4 processors are always mated with memory mounted on DIMMs B Although technically all slots listed could be used for video adapters PCle excels when compared to the other options and offers technologies such as SLI which only make PCle s advantage more noticeable
94. r System Components Identifying Purposes and Characteristics of Cooling Systems It s a basic concept of physics electronic components turn electricity into work and heat The heat must be dissipated or the excess heat will shorten the life of the components In some cases like the CPU the component will produce so much heat that it can destroy itself in a matter of seconds if there is not some way to remove this extra heat Most PCs use air cooling methods to cool their internal components With air cooling the movement of air removes the heat from the component Sometimes large blocks of metal called heat sinks are attached to a heat producing component in order to dissipate the heat more rapidly Fans When you turn on a computer you will often hear lots of whirring Contrary to popular opinion the majority of the noise isn t coming from the hard disk unless it s about to go bad Most of this noise is coming from the various fans inside the computer Fans provide airflow within the computer Most PCs have a combination of these six fans Front intake fan This fan is used to bring fresh cool air into the computer for cooling purposes Rear exhaust fan This fan is used to take hot air out of the case Power supply exhaust fan This fan is usually found at the back of the power supply and is used to cool the power supply In addition this fan draws air from inside the case into vents in the power supply This pulls hot air
95. r of conductors or pins that the particular physical specifi cation uses Some common examples include 168 184 and 240 pin configurations In addition laptop memory comes in smaller form factors known as small outline DIMMs SODIMMs and MicroDIMMs The single inline memory module SIMM is an older memory form factor that we ll discuss shortly More detail on memory packaging and the technologies that use them can be found later in this chapter in the section Identifying Purposes and Characteristics of Memory Figure 1 11 shows the form factors for some popular memory modules Notice how they basically look the same but the module sizes and keying notches are different 18 Chapter 1 Personal Computer System Components FIGURE 1 10 ACNRslot FIGURE 1 11 Different memory module form factors 144 pin SODIMM 2 625 x 1 72 pin SODIMM 2 375 x 1 Memory slots are easy to identify on a motherboard DIMM slots are usually black and placed very close together DIMM slots with pair by pair color coding can be observed these days however Generally the pairs of slots must be filled together for best performance or to work at all in some cases Consult the motherboard s documentation to determine the specific modules allowed as well as their required orientation The number of memory slots varies from motherboard to motherboard but the structure of the different slots is similar Metal pins in the bottom make contact with
96. r ones The first generation was the programmable ROM PROM which could be written to for the first time in the field using a special programming device 50 Chapter 1 Personal Computer System Components but then no more You had a new bug to keep the ROM bug company Liken this to the burn ing of a CD R Don t need it any longer You ve got a handy coaster Following the PROM came erasable PROM EPROM which was able to be erased using ultraviolet light and subse quently reprogrammed using the original programming device These days our flash memory is a form of electrically erasable PROM EEPROM which does not require UV light to erase its contents but rather a slightly higher than normal electrical pulse Although the names of these memory devices are different they all contain TE ROM Therefore regardless which of these technologies is used to manufac ture a BIOS chip it s never incorrect to say that the result is a ROM chip Memory Packaging First of all it should be noted that each motherboard supports memory based on the speed of the frontside bus and the memory s form factor For example if the motherboard s FSB is rated at a maximum speed of 533MHz and you install memory that is rated at 300 MHz the memory will operate at only 300MHz if it works at all thus making the computer oper ate slower than what it could In their documentation most motherboard manufacturers list which type s of memory they su
97. rface he In the spirit of covering interfaces that support both audio and video don t forget the HDMI interface which carries both over the same interface Only CATV coaxial connec tions to TV cards can boast that on the PC An RCA jack and cable carry either audio or video not both simultaneously Identifying Characteristics of Ports and Cables 61 PS 2 Keyboard and Mouse Another common port as mentioned earlier is the PS 2 port A PS 2 port also known as a mini DIN 6 connector is a mouse and keyboard interface port first found on the IBM PS 2 hence the name It is smaller than previous interfaces the DIN 5 keyboard port and serial mouse connector and thus its popularity increased quickly Figure 1 43 shows examples of both PS 2 keyboard and mouse ports You can tell the difference because the keyboard port is usually purple and the mouse port is usually green Also typically there are small graphics of a keyboard and mouse respectively imprinted next to the ports FIGURE 1 43 PS 2 keyboard and mouse ports 62 Chapter 1 Personal Computer System Components Centronics The last type of port connector is the Centronics connector a micro ribbon connector named for the Wang subsidiary that created it It has a unique shape as shown in Figure 1 44 It consists of a central connection bar surrounding by an outer shielding ring The Centronics connector was primarily used in parallel printer connections and SCSI int
98. rily with AMD processors including the Athlon XP 10 D A PS 2 port is also known as a mini DIN 6 connector 11 12 13 14 15 16 17 18 19 20 Answers to Review Questions 85 A C G DIMMs used in desktop motherboard applications have one of three possible pin counts SDR SDRAM is implemented on 168 pin modules DDR SDRAM and 16 bit RIMMs are implemented on 184 pin modules DDR2 and DDR3 are implemented on 240 pin modules with different keying Dual channel RIMM modules have 232 pins Modules with 200 and 204 pins are used in the SODIMM line and there are no modules with 180 pins D The USB 2 0 spec provides for a maximum speed of 480 megabits per second Mbps not megabytes per second or MBps C D Bidirectional parallel ports can both transmit and receive data EPP and ECP are IEEE 1284 standards that were designed to transfer data at high speeds in both directions so that devices could return status information to the system The standard parallel port only transmits data out of the computer It cannot receive data FireWire is specified by IEEE 1394 IEEE 1284 does not specify serial protocols such as RS 232 and USB C The 1394 standard provides for greater data transfer speeds and the ability to send memory addresses as well as data through a serial port B USBs are used to connect multiple peripherals to one computer through a single port They support data transfer rates as high as 12Mbps o
99. rimary memory During POST the BIOS also analyzes and catalogs other forms of hardware such as buses and boot devices as well as manages the passing of control to the specialized BIOS routines mentioned earlier The BIOS is responsible for offering the user a key sequence to enter the configuration routine as POST is beginning Finally once POST has completed successfully the BIOS selects the boot device highest in the configured boot order and executes the master boot record MBR or similar construct on that device so that the MBR can call its associated operating system and continue booting up 32 Chapter 1 Personal Computer System Components The POST process can end with a beep code or displayed code that indicates the issue dis covered Each BIOS publisher has its own series of codes that can be generated Figure 1 25 shows a simplified POST display during the initial boot sequence of a computer FIGURE 1 25 An example of a BIOS boot screen AMIBIOS C I2001 American Megatrends Inc BIOS Date 02 22 06 20 54 49 Ver 08 00 02 Press DEL to run Setup Checking NURAM 128MB OK fAuto Detecting Pri Channel 0 IDE Hard Disk Auto Detecting Pri Channel 1 IDE Hard Disk Auto Detecting Sec Channel 0 CDROM Auto Detecting Sec Channel 1 CMOS and CMOS Battery Your PC has to keep certain settings when it s turned off and its power cord is unplugged These settings include the following Date Time Hard dr
100. s integrated into the motherboard The first called a header connection allows you to mount the ports into the computer s case usually on the back plane with a special cable connected to a header or male connector that terminates the motherboard s traces for that function as shown in Figure 1 22 FIGURE 1 22 Connecting a port to the header on a motherboard The second method of connecting a peripheral port is known as the direct solder method With this method the individual ports are soldered directly to the motherboard This method is used mostly in integrated motherboards Figure 1 23 shows peripheral ports connected to a motherboard with the direct solder method Notice that there is no cable between the port and the motherboard and that the port is part of the motherboard Some of these onboard ports can be disabled in the BIOS setup if necessary You might need to disable an onboard port when an adapter with a more advanced version of the port or a replacement for a failed port is installed FIGURE 1 23 Peripheral ports directly soldered to a motherboard Identifying Components of Motherboards 31 BIOS and POST Aside from the processor the most important chip on the motherboard is the Basic Input Output System BIOS chip also referred to as the ROM BIOS chip This special memory chip contains the BIOS systems software that boots the system and allows the operating sys tem to interact with certain hardware in the comput
101. schemes affecting this extra bit are known as even odd mark and space Even and odd parity are used in systems that actually compute parity Mark a term for a 1 bit and space a term for a 0 bit parity are used in systems that do not compute parity but expect to see a fixed bit value stored in the parity location Systems that do not support or reserve the location required for the parity bit are said to implement non parity memory The most basic model for implementing memory in a computer system uses eight memory chips to form a set Each memory chip holds millions or billions of bits of informa tion For every byte in memory one bit is stored in each of the eight chips A ninth chip is added to the set to support the parity bit in systems that require it One or more of these sets implemented as individual chips or as chips mounted on a memory module forms 40 Chapter 1 Personal Computer System Components a memory bank A bank of memory is required for the computer system to electrically recognize that memory or additional memory has been installed The width of the system data bus the external bus of the processor dictates how many memory chips or modules are required to satisfy a bank For example one 32 bit 72 pin SIMM satisfies a bank for a 32 bit CPU such as a 386 or 486 processor Two such modules are required to satisfy a bank for a 64 bit processor a Pentium for instance However only a single 64 bit 168 pin DIMM is r
102. sided modules when you attempt to install a double sided module in the fourth slot you are essentially asking the mother board to accept five modules which it cannot Types of Memory Memory comes in many formats Each one has a particular set of features and characteris tics making it best suited for a particular application Some decisions about the application of the memory type are based on suitability others are based on affordability to consumers Identifying Purposes and Characteristics of Memory 43 or marketability to computer manufacturers The following list gives you an idea of the vast array of memory types and subtypes DRAM Asynchronous DRAM FPM DRAM EDO DRAM BEDO DRAM Synchronous DRAM SDR SDRAM DDR SDRAM DDR2 SDRAM DDR3 SDRAM DRDRAM SRAM ROM Pay particular attention to all synchronous DRAM types Note that the type of memory does not dictate the packaging of the memory Conversely however you might notice one particular memory packaging holding the same type of memory every time you come across it Nevertheless there is no requirement to this end Let s detail the intricacies of some of these memory types DRAM DRAM is dynamic random access memory This is what most people are talking about when they mention RAM When you expand the memory in a computer you are add ing DRAM chips You use DRAM to expand the memory in the computer because it s a cheaper type o
103. sive memory cooling method just uses the ambient case airflow to cool the memory through the use of 74 Chapter 1 Personal Computer System Components enhanced heat dissipation For this you can buy either heat sinks or as mentioned earlier special for memory chips only devices known as heat spreaders These are special alumi num or copper housings that wrap around memory chips and conduct the heat away from the memory chips Active cooling on the other hand usually involves forcing some kind of cooling medium air or water around the RAM chips themselves or around their heat sinks Most often active cooling methods are just high speed fans directing air right over a set of heat spreaders Hard Drive Cooling You might be thinking Hey my hard drive is working all the time Is there anything I can do to cool it off as well There are both active and passive cooling devices for hard drives Most common however is the active cooling bay You install a hard drive in a spe cial device that fits into a 54 expansion bay This device contains fans that draw in cool air over the hard drive thus cooling it Figure 1 56 shows an example of one of these active hard drive coolers As you might suspect you can also get heat sinks for hard drives FIGURE 1 56 An active hard disk cooler ce Chipset Cooling Every motherboard has a chip or chipset that controls how the computer operates As with other chips in the computer
104. sponding numerical value of the clock s frequency With today s processors interfacing with memory using a parallel data bus width of 8 bytes hence the term 64 bit processor a 1OOMHz clock signal pro duces 800MBps That s megabytes per second not megabits Such memory modules are referred to as PC100 named for the true FSB clock rate they rely on PC100 was preceded by PC66 and succeeded by PC133 which used a 133MHz clock to produce 1067MBps of throughput Note that throughput in megabytes per second is easily computed as eight times the rat ing in the name This trick works for the more advanced forms of SDRAM as well The common thread is the 8 byte system data bus Incidentally you can double throughput results when implementing dual channel memory DDR SDRAM Double data rate DDR SDRAM earns its name by doubling the transfer rate of ordinary SDRAM by double pumping the data which means transferring it on both the rising and Identifying Purposes and Characteristics of Memory 45 falling edges of the clock signal This obtains twice the transfer rate at the same FSB clock frequency It s the increasing clock frequency that generates heating issues with newer com ponents so keeping the clock the same is an advantage The same 100MHz clock gives a DDR SDRAM system the impression of a 200MHz clock in comparison to an SDR SDRAM system For marketing purposes and to aid in the comparison of disparate products DDR vs SDR for examp
105. t Airflow N Power Supply CPU lt lt lt lt _ Oe Case Fans SK Video card N Case Fan Hard Drive ieee naa e e NIC Motherboard Ne A Airflow Note that you must pay attention to the orientation of the power supply s airflow If the power supply fan is an exhaust fan as assumed in this discussion the front and rear fans will match their earlier descriptions front intake rear exhaust If you run across a power supply that has an intake fan the orientation of the supplemental chassis fans should be reversed as well The rear chassis fan s should always be installed in the same orientation as the power supply fan runs to avoid creating a small airflow circuit that circumvents the cross flow of air through the case The front chassis fan should always be installed in the reverse orientation of the rear fans to avoid fighting against them and reducing the internal airflow Reversing supplemental chassis fans is usually no harder than removing four screws and flipping the fan Sometimes the fan might just snap out flip and then snap back in depending on the way it is rigged up Memory Cooling If you are going to start overclocking your computer you will want to do everything in your power to cool all the components in your computer and that includes the memory There are two methods of cooling memory passive and active The pas
106. ted cabling including a fiber optic solu tion FireWire 800 extends to 100 meters IEEE 1394c proposes to run FireWire over the same Category Se infrastructure that supports Ethernet including the use of RJ 45 connectors FireWire also known as i LINK in Sony s parlance uses a very special type of cable as shown in Figure 1 52 for FireWire 400 Notice the difference in the system end on the left and the component end on the right It is difficult to mistake this cable for anything but a FireWire cable The beta connector of a FireWire 800 cable is equally distinctive Although most people think of FireWire as a tool for connecting their digital camcord ers to their computers it s much more than that Because of its high data transfer rate it is being used more and more as a universal high speed data interface for things like hard drives optical drives and digital video editing equipment 70 Chapter 1 Personal Computer System Components FIGURE 1 52 A FireWire IEEE 1394 alpha cable Because the FireWire specification was conceived to allow peripherals to be networked together in much the same fashion as intelligent hosts are networked together in LANs and WANs a quick introduction to the concept of networking is in order see Chapter 10 for more detail on networking concepts A topology can be thought of as the layout of the nodes that make up the endpoints and connecting devices of the network One of the most popular topologi
107. that would impose such a restriction on the system should eventually be developed for FSB attachment Most motherboards today have integrated PS 2 USB Parallel and Serial Some of the optional features handled by the Southbridge include LAN audio infrared and FireWire IEEE 1394 When first integrated the quality of onboard audio was marginal at best but the latest offerings rival external sound adapters in sound quality and number of features including Dolby Digital Theater Surround technology among others The Southbridge is also responsible for managing communications with the other expan sion buses such as PCI USB and legacy buses Figure 1 4 is a photo of the chipset of a motherboard with the heat sink of the North bridge at the top left connected to the cover of the Southbridge at the bottom right FIGURE 1 4 A modern computer chipset Ll fllelalalel tI ad ad A al 12 Chapter 1 Personal Computer System Components Figure 1 5 shows a schematic of a typical motherboard chipset both Northbridge and Southbridge and the components they interface with Notice which components interface with which parts of the chipset FIGURE 1 5 A schematic of a typical motherboard chipset CPU Cache Frontside Bus Pa Backside Bus Northbridge PCle Controller AGP Controller Memory Controller ATA Interface s Serial ATA Floppy Controller Onboard Audio
108. the power supply allowing the processor to run cooler And because those components are not in line with the expansion cards you can install full length expansion cards in an ATX mother board machine ATX and its derivatives are the primary motherboards in use today Micro ATX One form factor that is designed to work in standard ATX cases as well as its own smaller cases is known as micro ATX also referred to as pATX Micro ATX follows the same principle of component placement for enhanced cooling over pre ATX designs but with a smaller footprint With this smaller form come trade offs For the compact use of space you must give up quantity quantity of memory modules quantity of motherboard headers quantity of expansion slots quantity of integrated components even quantity of micro ATX chassis bays although the same small scale motherboard can fit into much larger cases if your original peripherals are still a requirement Be aware however that micro ATX systems tend to be designed with power supplies of lower wattage in order to help keep down power consumption and heat production which is generally acceptable with the standard micro ATX suite of components As more off board USB ports are added and larger cases are used with additional in case peripherals larger power supplies might be required New Low Profile Extended NLX An alternative motherboard form factor known as New Low Profile Extended NLX is used in some l
109. the chipset is normally cooled by the ambient air movement in the case However when you overclock a computer the chipset may need to be cooled more as it is working harder than it normally would be Therefore it is often desirable to replace the onboard chipset cooler with a more efficient one Refer back to Figure 1 4 for a look at a modern chipset cooling solution CPU Cooling Probably the greatest challenge in cooling is the cooling of the computer s CPU It is the com ponent that generates the most heat in a computer As a matter of fact if a modern processor isn t actively cooled all the time it will generate enough heat to burn itself up in an instant That s why most motherboards have an internal CPU heat sensor and a CPU_FAN sensor If no cooling fan is active these devices will shut down the computer before damage occurs There are a few different types of CPU cooling methods but the most important can be grouped into two broad categories air cooling and advanced cooling methods Identifying Purposes and Characteristics of Cooling Systems 75 Air Cooling The parts inside most computers are cooled by air moving through the case The CPU is no exception However because of the large amount of heat produced the CPU must have proportionately the largest surface area exposed to the moving air in the case Therefore the heat sinks on the CPU are the largest of any inside the computer This fan often blows air down throu
110. through the power supply so that it can be blown out of the case The front intake fan assists with this airflow The rear exhaust fan supplements the power supply fan to achieve the same result outside of the power supply CPU fan This fan is used to cool the processor Typically this fan is attached to a large heat sink which is in turn attached directly to the processor Chipset fan Some motherboard manufacturers replaced the heat sink on their onboard chipset with a heat sink and fan combination as the chipset became more advanced This fan aids in the cooling of the onboard chipset especially useful when overclocking Video card chipset fan As video cards get more complex and have higher performance more video cards have cooling fans directly attached Despite their name these fans don t attach to a chipset in the same sense as a chipset on a motherboard The chipset here is the set of chips mounted on the adapter including the graphics processing unit GPU and graphics memory Identifying Purposes and Characteristics of Cooling Systems 73 Memory module fan The more capable our memory becomes of keeping up with our CPU the hotter it runs As an extra measure of safety regardless of the presence of heat spreaders on the modules an optional fan setup for your memory might be in order See the following section for more Ideally the airflow inside a computer should resemble what is shown in Figure 1 55 FIGURE 1 55 _ System uni
111. timally the hot side should be mated with a heat sink or water block for heat dissipation Consequently TECs are not meant to replace air cooling mechanisms but to complement them 78 Chapter 1 Personal Computer System Components One of the downsides to TECs is the likelihood of condensation because of the sub ambient temperatures these devices produce Closed cell foams can be used to guard against damage from condensation Phase Change Cooling There is one new type of PC cooling that is just starting to be seen phase change cooling With this type of cooling the cooling effect from the change of a liquid to a gas is used to cool the inside of a PC It is a very expensive method of cooling but it does work Most often external air conditioner like pumps coils and evaporators cool the coolant which is sent ice cold to the heat sink blocks on the processor and chipset Think of it as a water cooling system that chills the water below room temperature It is possible to get CPU temps in the range of 4 F 20 C Normal CPU temperatures hover between 104 F and 122 F 40 C and 50 C The major drawback to this method is that in higher humidity conditions condensation can bea problem The moisture from the air condenses on the heat sink and can run off onto and under the processor thus shorting out the electronics Designers of phase change cooling systems offer solutions to help ensure this isn t a problem Products in the
112. trans mitted but don t compute the parity bit s value based on the bits in the byte Mark parity always uses a 1 in the parity bit and space parity always uses a 0 These schemes offer less error detection capability than the even and odd schemes because only changes in the parity bit can be detected Again parity checking is not error correction it s error detection only and not the best form of error detection at that Nevertheless finding an error can lock up the entire system and display a memory parity error Enough of these errors and you need to replace the memory In the early days of personal computing almost all memory was parity based Compaq was one of the first manufacturers to employ non parity RAM in their mainstream systems As quality has increased over the years parity checking in the RAM subsystem has become rarer As noted earlier if parity checking is not supported there will generally be fewer chips per module usually one less per column of RAM Error Checking and Correction The next step in the evolution of memory error detection is known as error checking and cor recting ECC If memory supports ECC check bits are generated and stored with the data An algorithm is performed on the data and its check bits whenever the memory is accessed If the result of the algorithm is all zeros then the data is deemed valid and processing continues ECC can detect single and double bit errors and actually correct single b
113. ultiplier of 2 in the SDRAM technology using a lower peak voltage to keep power consumption down 1 8V vs the 2 5V of DDR Still double pumping DDR2 like DDR uses both sweeps of the clock signal for data transfer Internally DDR2 further splits each clock pulse in two doubling the number of operations it can perform per FSB clock cycle Through enhancements in the electrical interface and buffers as well as through adding off chip drivers DDR2 nominally produces four times the throughput that SDR is capable of producing Continuing the DDR example DDR2 using a 100MHz actual clock transfers data in four operations per cycle effective 400M Hz FSB and still 8 bytes per operation for a total of 3200MBps Just like DDR DDR2 names its chips based on the perceived frequency In this case you would be using DDR2 400 chips DDR2 carries on the effective FSB frequency method for naming modules but cannot simply call them PC3200 modules because those already exist in the DDR world DDR2 calls these modules PC2 3200 note the dash to keep the numeric components separate As another example it should make sense that PC2 5300 modules are populated with DDR2 667 chips Recall that you might have to play with the numbers a bit If you multiply the well known FSB speed of 667MHz by 8 to figure out what modules you need you might go searching for PC2 5333 modules You might find someone advertising such modules but most compatible modules will be labe
114. y referred to as Integrated Drive Electronics IDE The AT component of the name was borrowed from the IBM PC AT which was the standard of the day However because ATA is not the only technology that integrates the drive controller circuitry into the drive assembly the anti quated Enhanced Small Device Interface ESDI for example was another IDE is some what of a misnomer and not the best term when referring only to ATA drives Nevertheless the original ATA standard was referred to as IDE and had an upper limit of 528MB per logical drive An enhanced version EIDE ATA 2 and higher was devel oped to circumvent the obstacles to accessing more drive space per volume increasing the limit to 8GB Since then the limit has been increased by the ATA 6 specification to 128PB 144 12e15 A petabyte PB is the number of bytes represented by 2 raised to the 50th power If your motherboard has PATA headers they will normally be black or some other neu tral color if they follow the classic ATA 40 wire standard If your PATA headers are blue they represent PATA interfaces that employ the ATA S5 or higher version of the Ultra DMA UDMA technology These headers require 80 wire ribbon cables that allow increased transfer rates by reducing crosstalk in the parallel signal These cables accomplish this by alternating among the other wires another 40 ground wires The connectors and headers are still 40 pins however The color coding alerts you to the

Wiley CompTIA A+ Complete Study Guide: Exams 220-701 (Essentials) and 220-702 (Practical Application)

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