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CHAPTER 18 - Pearsoncmg

1. 35g 45g O 55g 65g 80g Figure 18 6 Force levels used on KeyTronicEMS keyboards with Ergo Technology Capacitive Switches Capacitive switches are the only nonmechanical keyswitch in use today see Figure 18 7 The capaci tive switch is the Cadillac of keyswitches It is much more expensive than the more common mechani cal membrane switch but it is more resistant to dirt and corrosion and offers the highest quality tactile feedback of any type of switch This type of keyboard is sometimes referred to as a buckling spring key board because of the coiled spring used to provide feedback A capacitive switch does not work by making contact between conductors Instead two plates usually made of plastic are connected in a switch matrix designed to detect changes in the capacitance of the circuit When the key is pressed the plunger moves the top plate in relation to the fixed bottom plate Typically a buckling spring mechanism provides for a distinct over center tactile feedback with a resounding click As the top plate moves the capacitance between the two plates changes The com parator circuitry in the keyboard detects this change 1026 Chapter 18 Input Devices Key Return spring Upper plate is movable Lower plate P is fixed Oscillator _y joek eop Reference Comparator gt Output Figure 18 7 A capacitive buckling sp
2. Figure 18 2 Most portable systems today embed the numeric keypad into an oddly shaped block of keys on the alphabetical part of the keyboard To alleviate this problem many portable system manufacturers sell external numeric keypads that plug into the external keyboard port a serial port or a USB port This is a great feature for somebody performing a lot of numeric data entry In addition to keypad control the Fn key often is used to trigger other proprietary features in portable systems such as toggling between an internal and external display and controlling screen brightness and sound volume Some portable system manufacturers have gone to great lengths to provide users with adequate key boards For a short time IBM marketed systems with a keyboard that used a butterfly design The keyboard was split into two halves that rested on top of one another when the system was closed When you opened the lid the two halves separated to rest side by side forming a keyboard that was actually larger than the computer case Ironically the trend toward larger sized displays in portable systems has made this sort of arrange ment unnecessary Many manufacturers have increased the footprint of their notebook computers to accommodate 14 1 and even 15 display panels leaving more than adequate room for a keyboard with full size keys However even on the newest systems there still isn t enough room for a s
3. IBM also assigns each key a unique key number to distinguish it from the others This is important when you are trying to identify keys on foreign keyboards that might use symbols or characters differ ent from what the U S models do In the Enhanced keyboard most foreign models are missing one of the keys key 29 found on the U S version and have two additional keys keys 42 and 45 This accounts for the 102 key total instead of the 101 keys found on the U S version 1030 Chapter 18 Input Devices Note See the Technical Reference section of the disc included with this book for a comprehensive listing of keyboard key num bers and scan codes for both the 101 102 key Enhanced keyboard and 104 key Windows keyboard including HID and hotkey scan codes used on the latest USB and hotkey keyboards Knowing these key number figures and scan codes can be useful when you are troubleshooting stuck or failed keys on a keyboard Diagnostics can report the defective keyswitch by the scan code which varies from keyboard to keyboard on the character it represents and its location Many enhanced and USB keyboards now feature hotkeys that either have fixed uses such as opening the default Web browser sending the system into standby mode and adjusting the speaker volume or are programmable for user defined functions Each of these keys also has scan codes USB key boards use a special series of codes called Human Interface Device HID
4. or COM2 The device driver when initializing searches the ports to determine to which one the mouse is connected Some mouse drivers can t function if the serial port is set to COM3 or COM4 but most newer drivers can work with any COM port 1 4 Because a serial mouse does not connect to the system directly it does not use system resources by itself Instead the resources are those used by the serial port to which it is connected For example if you have a mouse connected to COM2 and if COM2 is using the default IRQ and I O port address range both the serial port and the mouse connected to it use IRQ3 and I O port addresses 2F8h 2FFh See Serial Ports p 997 Motherboard Mouse Port PS 2 Most computers include a dedicated mouse port built into the motherboard This practice was intro duced by IBM with the PS 2 systems in 1987 so this interface is often referred to as a PS 2 mouse inter face This term does not imply that such a mouse can work only with a PS 2 instead it means the mouse can connect to any system that has a dedicated mouse port on the motherboard From a hardware perspective a motherboard mouse connector is usually exactly the same as the mini DIN connector used for newer keyboards In fact the motherboard mouse port is connected to the 8042 type keyboard controller found on the motherboard All the PS 2 computers include mini DIN keyboard and mouse port connectors on the back Most computers based on the sem
5. I asked him when such keyboards would become available he could not answer At the time there were apparently no plans for production and he was only trying to test user reaction to the device Just over six months later IBM announced the ThinkPad 700 which included this revolutionary device then called the TrackPoint II Integrated Pointing Device Since the original version came out enhanced versions with greater control and sensitivity called the TrackPoint III and IV have become available Note The reason the device was called TrackPoint Il is that IBM had previously been selling a convertible mouse trackball device called the TrackPoint No relationship exists between the original TrackPoint mouse trackball which has since been discontinued and the TrackPoint Il integrated device Since the original TrackPoint Il came out improved versions known as TrackPoint Ill and TrackPoint IV have become available In the interest of simplicity will refer to all the TrackPoint Il Ill and successive devices as just TrackPoint In its final production form the TrackPoint consists of a small red silicone rubber knob nestled between the G H and B keys on the keyboard The primary and secondary mouse buttons are placed below the spacebar where you can easily reach them with your thumbs without taking your hands off the keyboard IBM studies conducted by Selker found that the act of removing your hand from the keyboard to reach for a
6. additional trilograms plus the additional Windows keys adds somewhat to the cost of these keyboards compared to the previous 101 key standard models Virtually all keyboard manufacturers have standardized on 104 key keyboards that include these Windows specific keys Some manufacturers have added browser control or other keys that although not standard can make them easier to use for navigating Web pages and launching various applications For additional keyboard combinations you can use see Running Windows Without a Mouse in the Technical Reference section of the disc included with this book USB Keyboards Most keyboards now on the market can connect to the PC via a USB port instead of the standard PS 2 keyboard port Because USB is a universal bus that uses a hub to enable multiple devices to connect to a single port a single USB port in a system can replace the standard serial and parallel ports as well as the keyboard and mouse ports Most current systems and motherboards still include the standard ports now called legacy ports as well as USB but most so called legacy free systems and replacement mother boards have only USB ports for interfacing external devices Most keyboard manufacturers now market USB keyboards but if you want to use your keyboard with both legacy PS 2 and legacy free USB systems the most economic way to do so is to specify a key board that includes both a USB connector and an adapter to permit the keybo
7. can prevent IR input devices from working correctly 12 ft B A Obstructive object Acceptable angle for receiving transmissions Not acceptable IR transceiver ODP Mouse with IR connection to transceiver Mouse can t connect out of range Mouse can t connect line of sight blocked Mouse can t connect wrong angle to transceiver RON Figure 18 15 A wireless mouse using IR technology must be within range of the transceiver at the cor rect angle to the transceiver and not blocked by any objects Otherwise it cannot work 1054 Chapter 18 Input Devices Because of the problems with IR devices shown in Figure 18 15 almost all vendors of wireless input devices now use radio waves RF for transmission between the device and transceiver RF based wire less devices have no line of sight problems but most have a limited range of about 6 ft from the transmitter see Figure 18 16 NS 1 I u Obstructive object I I 1 Li A Acceptable angle for receiving transmissions 360 B RF transceiver 1 Mouse can t connect out of range 2 Mouse with connection to RF transceiver Figure 18 16 A wireless mouse using RF must be within range of the transceiver but unlike IR based wireless mice the angle of the mouse to the transceiver doesn t matter and radio signals can t be blocked by books paper or other obstacles Although RF overcomes line of sight issues that can cripp
8. chip translates the actual keyboard scan codes into one of up to three sets of system scan codes which are sent to the main processor It can be useful in some cases to know what these scan codes are especially when trouble shooting keyboard problems or when reading the keyboard or system scan codes directly in software When a keyswitch on the keyboard sticks or otherwise fails the Make scan code of the failed keyswitch usually is reported by diagnostics software including the power on self test POST as well as conventional disk based diagnostics This means you must identify the malfunctioning key by its scan code See the Technical Reference section of the disc included with this book for a comprehen sive listing of keyboard key numbers and scan codes for both the 101 102 key Enhanced keyboard and 104 key Windows keyboard By looking up the reported scan code on these charts you can deter mine which keyswitch is defective or needs to be cleaned Note The 101 key Enhanced keyboards are capable of three scan code sets Set 1 is the default Some systems including some of the IBM PS 2 machines use one of the other scan code sets during the POST For example my IBM P75 uses Scan Code Set 2 during the POST but switches to Set 1 during normal operation This is rare and it really threw me off in diagnosing a stuck key problem one time It is useful to know whether you are having difficulty interpreting the scan code number however
9. devices for multiple computers you should be aware of the fol lowing issues E Line of site issues Infrared devices won t work if the IR beam between the pointing device and the transceiver attached to the system is blocked These units are not as suitable for casual in the lap use as radio frequency units are E Radio frequency interference Although early wireless mice used analog tuners that were hard to synchro nize today s wireless input devices typically use digital selectors However if several similar devices are used in close quarters a transceiver might actually receive data from the wrong mouse or keyboard Also metal desks and furniture can reduce range and cause erratic cursor movement Most wireless devices operate around 27MHz minimizing interference from devices such as cordless phones If you plan to install several different computers using wireless input devices in the same room set up one at a time and allow about half an hour between installations if possible to let each unit synchronize with its transceiver Check with the vendor for other tips on overcoming interference issues E Battery life and availability Early wireless devices sometimes used unusual expensive batteries Today s units run on common battery types such as AAA or AA Battery life is usually rated at about 6 months for keyboards or ball type mice and about 2 3 months for optical mice Be sure you have spare batteries for the input device to avoi
10. distilled the distinct taste of many bottled waters comes from the trace minerals they contain Also make sure the keyboard is fully dry before you try to use it otherwise some of the components might short out 1036 Chapter 18 Input Devices Tip If spills or excessive dust or dirt are expected because of the environment or conditions in which the PC is used several companies make thin membrane skins that mold over the top of the keyboard protecting it from liquids dust and other con taminants These skins are generally thin enough so that they don t interfere too much with the typing or action of the keys Keyboard Recommendations In most cases replacing a keyboard is cheaper or more cost effective than repairing it This is espe cially true if the keyboard has an internal malfunction or if one of the keyswitches is defective Replacement parts for keyboards are almost impossible to procure and installing any repair part is usually difficult In addition many of the keyboards supplied with lower cost PCs leave much to be desired They often have a mushy feel with little or no tactile feedback A poor keyboard can make using a system a frustrating experience especially if you are a touch typist For all these reasons it is often a good idea to replace an existing keyboard with something better Perhaps the highest quality keyboards in the entire computer industry are those made by IBM or more accurately today U
11. it in soapy water or a mild solvent such as contact lens cleaner solution or alcohol and dry it off Now take a look at the socket in which the roller ball normally rests You will see two or three small wheels or bars against which the ball usually rolls If you see dust or dirt on or around these wheels or bars you need to clean them The best way is to use a compressed air duster which can blow out any dust or dirt You also can use some electrical contact cleaner to clean the rollers Remember any remaining dirt or dust impedes the movement of the roller ball and results in the mouse not working as it should Put the mouse back together by inserting the roller ball into the socket and then securely attaching the cover panel The mouse should look just as it did before you removed the panel except that it will be noticeably cleaner One of the major advantages of the new breed of optical mice is the lack of moving parts Just wipe away dust from the optical sensor and that s all the cleaning an optical mouse needs Pointing Devices Chapter 18 1045 Interrupt Conflicts lt lt gt gt Interrupts are internal signals used by your computer to indicate when something needs to happen With a mouse an interrupt is used whenever the mouse has information to send to the mouse driver If a conflict occurs and the same interrupt used by the mouse is used by a different device the mouse will not work properly if at all
12. keyboard built in Trackball cable w DIN plug 92G7456 IBM Enhanced keyboard built in Trackball cable w mini DIN plug 92G7455 IBM Enhanced keyboard integrated TrackPoint Il cables w mini DIN plugs 92G7461 IBM TrackPoint IV keyboard Black 01K1260 IBM TrackPoint IV keyboard White 01K1259 IBM TrackPoint USB Space Saver keyboard black 22P5150 IBM USB Keyboard with two port hub black 10K3849 IBM Rapid Access III black 22P5185 Pointing Devices Chapter 18 1037 Keep in mind though that because IBM spun off its keyboard business some years ago many recent and current IBM labeled keyboards no longer have the distinct feel quality or durability found in the older models Ironically one of the best ways to get an IBM keyboard is to buy the model with the features you want from Unicomp most of whose keyboards still use the capacitive buckling spring technology IBM originally made famous The extremely positive tactile feedback of the IBM Lexmark Unicomp design is also a benchmark for the rest of the industry Although keyboard feel is an issue of personal preference I have never used a keyboard that feels better than the IBM Lexmark Unicomp designs I now equip every system I use with a Unicomp keyboard including the many non IBM systems I use You can purchase these key boards directly from Unicomp at very reasonable prices Many models are available including some with a built in trackball or even the r
13. restart the system E Some users of Windows 98 and Windows 98 SE have reported conflicts between Windows and the BIOS when USB Legacy support is enabled on some systems This conflict can result in an incapability to detect the USB keyboard if you use the Windows 9x shutdown menu and choose to restart the computer in MS DOS mode Check with the system or BIOS vendor for an updated BIOS or a patch to solve this conflict If you have problems with Legacy USB support look at these possible solutions E Microsoft s Knowledge Base might address your specific combination of hardware E Your keyboard vendor might offer new drivers E Your system or motherboard vendor might have a BIOS upgrade you can install E Connect the keyboard to the PS 2 port with its adapter or use a PS 2 keyboard until you resolve the problem See Universal Serial Bus p 983 Notebook Computer Keyboards One of the biggest influences on keyboard design in recent years has been the proliferation of laptop and notebook systems Because of size limitations it is obviously impossible to use the standard key board layout for a portable computer Manufacturers have come up with many solutions Unfortunately none of these solutions has become an industry standard as the 101 key layout is Because of the varia tions in design and because a portable system keyboard is not as easily replaceable as that of a desktop system the keyboard arrangement should be an importan
14. somewhat similar connector to attach the keyboard cable to the inside of the keyboard You can use the pinouts listed in Table 18 2 to test the continuity of each wire in the keyboard connector Plug Socket 4 5 5 4 2 2 5 6 6 5 Mini DIN 3 4 4 3 6 pin N ie 6 pin SDL ABCDEF FEDCBA Figure 18 8 Keyboard and mouse connectors 1032 Chapter 18 Input Devices Table 18 2 Keyboard Connector Signals and Specifications Signal Name 5 Pin DIN 6 Pin Mini DIN 6 Pin SDL Test Voltage Keyboard Data 2 1 B 4 8V to 5 5V Ground 4 3 C 5V Power 5 4 E 2 0V to 5 5V Keyboard Clock 1 5 D 2 0V to 5 5V Not Connected 2 A Not Connected 6 F Not Connected 3 DIN Deutsches Institut f r Normung e V a committee that sets German dimensional standards SDL Shielded data link a type of shielded connector created by AMP and used by IBM and others for keyboard cables Motherboard non USB mouse connectors also use the 6 pin mini DIN connector and have the same pinout and signal descriptions as the keyboard connector however the data packets are incompatible Therefore you can easily plug a motherboard mouse PS 2 style into a mini DIN keyboard connector or plug the mini DIN keyboard connector into a motherboard mouse port Neither one will work properly in this situation though Caution have also seen PCs with external power supplies that used the same standard DIN connectors t
15. system for the first time If USB Legacy support is not enabled on the system a USB keyboard will function only when Windows is running Most recent systems include USB Legacy support although it might be disabled by default in the sys tem BIOS 1020 Chapter 18 Input Devices lt lt Also if the Windows installation fails and requires manipulation outside of Windows the USB keyboard will not function unless it is supported by the chipset and the BIOS Almost all 1998 and newer systems with USB ports include a chipset and BIOS with USB Legacy meaning USB Keyboard support Even though USB Legacy support enables you to use a USB keyboard in almost all situations don t scrap your standard port keyboards just yet Some Windows related bugs and glitches reported by users include the following E Can t log on to Windows the first time after installing a USB keyboard The solution in some cases is to click Cancel when you are asked to log on and then allow the system to detect the keyboard and install drivers The logon should work normally thereafter In other cases you might have to leave the keyboard unplugged when first booting and then plug it in after the OS desktop is up and running This allows the keyboard to be detected and drivers loaded E Some USB keyboards won t work when the Windows Emergency Boot Disk EBD is used to start the sys tem The solution is to turn off the system connect a standard keyboard and
16. that moves thus issuing a system interrupt takes precedence and retains control over the mouse pointer on the screen until it completes its movement action The second pointing device is automatically locked out until the primary device is stationary This enables the use of both devices and prevents each one from interfering with the other IBM has added various versions of the TrackPoint to its notebook computers as well as to high end keyboards sold under the IBM Lexmark and Unicomp names Notebook computer makers such as HP and Toshiba also have licensed the TrackPoint device Toshiba calls it Accupoint I have compared the TrackPoint device to other pointing devices for notebooks such as the trackballs and even the capacitive touch pads but nothing compares in terms of accuracy and control and of course you don t have to take your hands off the keyboard Some notebook computer makers copied the TrackPoint instead of licensing it but with poor results that include sluggish response to input and poor accuracy One way of telling whether the TrackPoint device is licensed from IBM and uses the IBM technology is if it accepts IBM TrackPoint I II IV rub ber caps They have a square hole in them and will properly lock on to any of the licensed versions such as those found in Toshiba systems IBM has upgraded its pointing stick to the TrackPoint III and the current TrackPoint IV Two main dif ferences exist in the III IV system but t
17. the term GlidePoint for its touch pads The GlidePoint uses a flat square pad that senses finger position through body capacitance This is similar to the capacitance sensitive elevator button controls you sometimes encounter in office buildings or hotels When it is used on a portable computer s keyboard the touch pad is mounted below the spacebar and it detects pressure applied by your thumbs or fingers Transducers under the pad convert finger movement into pointer movement Several laptop and notebook manufacturers have licensed this technology from Cirque and have incorporated it into their portable systems Touch pads are also integrated into a number of mid range to high end keyboards from many vendors When used on a desktop keyboard touch pads are often offset to the right side of the keyboard s typing area Touch pads feature mouse buttons although the user also can tap or double tap on the touch pad s surface to activate an onscreen button located under the touch pad s cursor Dragging and dropping is accomplished without touching the touch pad s buttons just move the cursor to the object to be 1050 Chapter 18 Input Devices dragged press down on the pad hold while moving the cursor to the drop point and raise the finger to drop the object Some recent models also feature additional hot buttons with functions similar to those on hot button keyboards The primary use for touch pads has been for notebook compute
18. to perform To test each wire of the cable insert the DMM s red pin into the keyboard connector and touch the DMM s black pin to the corresponding wire that attaches to the keyboard s circuit board Wiggle the ends of the cable as you check each wire to ensure no intermittent connections exist If you discover a problem with the continuity in one of the wires replace the cable or the entire key board whichever is cheaper Because replacement keyboards are so inexpensive it s almost always cheaper to replace the entire unit than to get a new cable unless the keyboard is a deluxe model For more information about using digital multimeters for testing hardware see Chapter 24 PC Diagnostics Testing and Maintenance Many times you first discover a problem with a keyboard because the system has an error during the POST Many systems use error codes in a 3xx numeric format to distinguish the keyboard If you encounter any such errors during the POST write them down Some BIOS versions do not use cryptic numeric error codes they simply state something such as the following Keyboard stuck key failure This message is usually displayed by a system with a Phoenix BIOS if a key is stuck Unfortunately the message does not identify which key it is If your system displays a 3xx keyboard error preceded by a two digit hexadecimal number the num ber is the scan code of a failing or stuck keyswitch Look up the scan code in the tabl
19. to a serial port If this does not work it is not the fault of the adapter If the mouse does not explicitly state that it is both a serial and a PS 2 type mouse it works only on the sin gle interface for which it was designed Most of the time you find the designation for which type of mouse you have printed on its underside A safe rule of thumb to follow is if the mouse didn t come with an adapter or come bundled with a system it probably won t work with an adapter USB The extremely flexible USB port has become the most popular port to use for mice as well as key boards and other I O devices Compared to the other interfaces USB mice and other USB pointing devices such as trackballs have the following advantages USB mice move much more smoothly than the traditional PS 2 type This is because the frequency with which the mouse reports its position is much higher A typical PS 2 mouse has a reporting rate of about 40Hz whereas an average USB wired mouse has a reporting rate of 125Hz most USB wireless mice have a reporting rate of 40Hz 50Hz Several utilities are available to test and adjust the mouse frequency E Mice with the most advanced features are usually made especially for the USB port One example is the Logitech iFeel mouse the first mouse with an optical sensor plus force feedback It vibrates gently as you move the mouse over clickable buttons on Web pages software menus and the Windows desktop and it s made esp
20. which are translated into PS 2 scan codes International Keyboard Layouts After the keyboard controller in the system receives the scan codes generated by the keyboard and passes them to the main processor the operating system converts the codes into the appropriate alphanumeric characters In the United States these characters are the letters numbers and symbols found on the standard American keyboard However no matter which characters you see on the keytops adjusting the scan code conversion process to map different characters to the keys is relatively simple Windows post 3 x takes advan tage of this capability by enabling you to install multiple keyboard layouts to support various lan guages In Windows 9x Me open the Keyboard icon in the Control Panel and select the Language page The Language box should display the keyboard layout you selected when you installed the operating sys tem In Windows XP click the Details button found on the Languages tab in the Regional and Language Options applet in the Windows Control Panel By clicking the Add button you can select any one of several additional keyboard layouts supporting other languages These keyboard layouts map various characters to certain keys on the standard keyboard The stan dard French layout provides easy access to the accented characters commonly used in that language For example pressing the 2 key produces the character To type the numeral 2 you press the
21. yourself for typing file management and simple graphics and see which type of integrated pointing device you prefer I know what I like but you might have different tastes Trackballs The first trackball I ever saw outside of an arcade was the Wico trackball a perfect match for mid 1980s video games and computer games such as Missile Command and others It emulated the eight position Atari 2600 analog joystick but was capable of much more flexibility Unlike the mid 80s trackballs today s trackballs are used primarily for business instead of gaming Most trackballs use a mouse style positioning mechanism the differences being that the trackball is on the top or side of the case and is much larger than a mouse ball The user moves the trackball rather than the input device case but rollers or wheels inside most models translate the trackball s motion and move a cursor onscreen the same way that mouse rollers or wheels convert the mouse ball s motion into cursor movement Trackballs come in a variety of forms including ergonomic models shaped to fit the right hand ambidextrous models suitable for both lefties and right handers optical models that use the same optical sensors found in the latest mice in place of wheels and rollers and multibutton monsters that look as if they re the result of an encounter with a remote control Because they are larger than mice trackballs lend themselves well to the extra electronics and batt
22. CHAPTER 18 Input Devices 1016 Chapter 18 Input Devices Keyboards One of the most basic system components is the keyboard which is the primary input device It is used for entering commands and data into the system This section looks at the keyboards available for PC compatible systems examining the various types of keyboards how the keyboard functions the keyboard to system interface and keyboard troubleshooting and repair In the years since the introduction of the original IBM PC IBM has created three keyboard designs for PC systems and Microsoft has augmented one of them These designs have become de facto stan dards in the industry and are shared by virtually all PC manufacturers The primary keyboard types are as follows E 101 key Enhanced keyboard E 83 key PC and XT keyboard obsolete E 104 key Windows keyboard E 84 key AT keyboard obsolete This section discusses the 101 key Enhanced keyboard and the 104 key Windows keyboard showing the layout and physical appearance of both Although you can still find old systems that use the 83 key and 84 key designs these are rare today Because all new systems today use the 101 or 104 key keyboard design these versions are covered here Note If you need to learn more about the 83 key PC and XT keyboard or the 84 key AT keyboard see Chapter 7 of Upgrading and Repairing PCs 10th Anniversary Edition on the disc included with this book Enhanced 101 Key o
23. Interrupt conflicts caused by mice can occur when a serial or PS 2 mouse is used but not when a USB mouse is used Mouse ports built in to modern motherboards are almost always set to IRQ12 If your system has a motherboard mouse port be sure you don t set any other adapter cards to IRQ12 other wise a conflict will result If you are using a serial mouse interrupt conflicts typically occur if you add third and fourth serial ports using either an expansion card or internal serial device such as a modem This happens because in ISA bus systems the odd numbered serial ports 1 and 3 usually are configured to use the same interrupts as the even numbered ports 2 and 4 are IRQ4 is shared by default between COM1 and COM3 and IRQ 2 is shared by default between COM2 and COM4 Therefore if your mouse is connected to COM2 and an internal modem uses COM4 they both might use the same interrupt and you can t use them at the same time Because the mouse generates interrupts only when it is moved you might find that the modem func tions properly until you touch the mouse at which point the modem is disconnected Another example is when your system will run properly until you try to go online with your modem then the conflict usually locks up the system You might be able to use the mouse and modem at the same time by mov ing one of them to a different serial port For instance if your mouse uses COM1 and the modem still uses COM4 you can use th
24. Shift 2 key combination Other French speaking countries have different keyboard conventions for the same characters so Windows includes support for several keyboard layout variations for some languages based on nationality Note lt is important to understand that this feature is not the same as installing the operating system in a different language These keyboard layouts do not modify the text already displayed onscreen they only alter the characters generated when you press certain keys The alternative keyboard layouts also do not provide support for non Roman alphabets such as Russian and Chinese The accented characters and other symbols used in languages such as French and German are part of the standard ASCII character set They are always accessible to English language users through the Windows Character Map utility or through the use of Alt keypad combina tions An alternative keyboard layout simply gives you an easier way to access the characters used in certain languages Keyboard Technology Chapter 18 1031 If you work on documents using more than one language you can install as many keyboard layouts as necessary and switch between them at will When you click the Enable Indicator on Taskbar check box on the Language page of the Keyboard control panel a selector appears in the taskbar s tray area that enables you to switch languages easily On the same page you can enable a key combination that switches bet
25. Their versatility and low maintenance not to mention that neat red or blue glow out the sides make optical mice an attractive choice and the variety of models available from both vendors means you can have the latest optical technology for about the price of a good ball type mouse Figure 18 12 shows the interior of a typical optical mouse Printed circuit board PCB Clip holding sensor LED subassembly Lens light pipe Sensor Base plate LED bottom of mouse Mousing surface Figure 18 12 The LED inside an optical mouse illuminates the surface by blinking many times per sec ond The light is reflected from the mousing surface back to the sensor which converts the information into digital form and sends it to the computer All optical mice have a resolution of at least 400dpi and at least one sensor However for better per formance some optical mice have improved on these basic features as listed in Table 18 4 Pointing Devices Chapter 18 1041 Table 18 4 Enhanced Optical Mouse Features Feature Benefit Sample Product 800dpi optical Improves accuracy for mouse positioning Logitech MX series Microsoft IntelliMouse resolution Explorer and Optical series Larger sensor size Improves tracking on surfaces with Logitech MX series repetitive patterns such as wood desktops Faster tracking speed Able to keep up with fast
26. able programmable read only memory EPROM can be erased and reprogrammed In the past when you purchased a motherboard ROM upgrade for an older system from a motherboard manufacturer the upgrade included a new key board controller chip as well because it had somewhat dependent and updated ROM code in it Some older systems might use the 8041 or 8741 chips which differ only in the amount of built in ROM or RAM However recent systems incorporate the keyboard controller into the main system chipset In an AT system the 8048 type microcontroller in the keyboard sends data to the 8042 type key board controller on the motherboard The motherboard based controller also can send data back to the keyboard When the keyboard controller on the motherboard receives data from the keyboard it sig nals the motherboard with an IRQ1 and sends the data to the main motherboard processor via I O port address 60h just as in the PC XT Acting as an agent between the keyboard and the main system processor the 8042 type keyboard controller can translate scan codes and perform several other func tions as well The system also can send data to the 8042 keyboard controller via port 60h which then passes it on to the keyboard Additionally when the system needs to send commands to or read the status of the keyboard controller on the motherboard it reads or writes through I O port 64h These commands usually are followed by data sent back and forth via port 60h I
27. ade ultra realistic flying driving and fighting simulators possible USB controllers offer the addi tional speed necessary for more sophisticated gamers USB Ports for Gaming The USB port has become the preferred connector for all types of gaming controllers including joy sticks gamepads and steering wheels Instead of making a single inadequate joystick work for all types of games users can now interchange controllers using the hot swap benefits of USB and use the best controller for each type of game Although a few low end game controllers still on the market can connect to either the venerable game port or the serial port serious gamers want USB because of its higher speed better support for force feedback which shakes the game controller realistically to match the action onscreen and tilt ing tilt the gamepad and the onscreen action responds As with USB mice your USB connected gaming controllers are only as good as their software drivers Be sure to install the latest software available to keep up with the latest games Compatibility Concerns If you play a lot of older games designed in the heyday of the 15 pin gameport consider keeping a gameport type controller Even though the vendors of USB game controllers strive to make the USB port emulate a game port for use with older games some older games can t be fooled If you have problems using a USB game controller with a specific game check the game s Web site for pat
28. alled ergonomic designs The goal is to shape the keyboard to better fit the human hand The most common of these designs splits the keyboard in the center bending the sides outward Some designs allow the angle between the sides to be adjusted Keyboard Troubleshooting and Repair Chapter 18 1033 such as the now discontinued Lexmark Select Ease the Goldtouch keyboard designed by Mark Goldstein who also designed the Select Ease and the Kinesis Maxim split keyboards Others such as the Microsoft Natural keyboard series PC Concepts Wave and Cirque Smooth Cat are fixed These split or bent designs more easily conform to the hands natural angles while typing than the standard keyboard They can improve productivity and typing speed and help prevent repetitive strain injuries RSI such as carpal tunnel syndrome tendon inflammation Even more radical keyboard designs are available from some vendors including models such as the 3 part Comfort and ErgoMagic keyboards the Kinesis concave contoured keyboard and others A good source for highly ergonomic keyboards pointing devices and furniture is Ergonomic Resources www ergo 2000 com Because of their novelty and trendy appeal some ergonomic keyboards can be considerably more expensive than traditional designs but for users with medical problems caused or exacerbated by improper positioning of the wrists at the keyboard they can be an important remedy to a serious problem Gen
29. ansceiver by pressing a button or you might need to remove the battery reinsert the battery and wait for several minutes to reestablish contact E Interference between units Check the transmission range of the transceivers in your wireless units and visit the manufacturer s Web site for details on how to reduce interference Typically you should use different frequencies for wireless devices on adjacent computers E Blocked line of sight If you are using infrared wireless devices check the line of sight carefully at the computer the space between your device and the computer and the device itself You might be dangling a finger or two over the infrared eye and cutting off the signal the equiva lent of putting your finger over the lens on a camera E Serial port IRQ conflicts If the wireless mouse is connected to a serial port and it stops working after you install another add on card check for conflicts using the Windows Device Manager E Disconnected transceiver If you have moved the computer around you might have disconnected the transceiver from its keyboard PS 2 mouse serial or USB port You can plug a USB device in without shutting down the system but the other types require you to shut down reattach the cable and restart to work correctly E USB Legacy support not enabled If your wireless keyboard uses a transceiver connected to the USB port and the device works in Windows but not at a command prompt make sure you h
30. ard for keyboard layouts outlines a set of additional keys and key combinations The 104 key layout includes left and right Windows keys and an Application key see Figure 18 1 These keys are used for operating system and application level keyboard combinations similar to the existing Ctrl and Alt combinations You don t need the new keys to use Windows but software vendors are adding specific functions to their Windows products that use the new Application key which provides the same 1018 Chapter 18 Input Devices functionality as clicking the right mouse button The recommended Windows keyboard layout calls for the Left and Right Windows keys called WIN keys to flank the Alt keys on each side of the space bar as well as an Application key on the right of the Right Windows key Note that the exact place ment of these keys is up to the keyboard designer so variations exist from keyboard to keyboard Left Windows key Right Windows key Figure 18 1 The 104 key Windows keyboard layout The WIN keys open the Windows Start menu which you can then navigate with the cursor keys The Application key simulates the right mouse button in most applications it brings up a context sensitive pop up menu Several WIN key combinations offer preset macro commands as well For example you can press WIN E to launch the Windows Explorer application Table 18 1 shows a list of al
31. ard to work with PS 2 ports Although Microsoft s Natural Keyboard Elite was the first widely available model to offer USB and PS 2 compatibility other wired and wireless models from Microsoft Logitech Belkin and others now offer this feature You can also purchase third party USB to PS 2 adapters but these can be expen sive and might not work with all keyboards Not all systems accept USB keyboards even those with USB ports because the standard PC BIOS has a keyboard driver that expects a standard keyboard port interface to be present When a USB keyboard is installed on a system that lacks USB keyboard support the system can t use it because no driver exists in the BIOS to make it work In fact some systems see the lack of a standard keyboard as an error and halt the boot process until one is installed To use a keyboard connected via the USB port you must meet three requirements E Have a USB port in the system E Run Microsoft Windows 98 Windows Me Windows 2000 or Windows XP all of which include USB keyboard drivers E Have a system chipset and BIOS that feature USB Legacy support USB Legacy support means your motherboard has a chipset and ROM BIOS drivers that enable a USB keyboard to be used outside the Windows GUI environment When a system has USB Legacy support enabled a USB keyboard can be used with MS DOS for configuring the system BIOS when using a command prompt within Windows or when installing Windows on the
32. ate slider are worth about one character per second each The dialog box also contains a text box you can use to test the settings you have chosen before com mitting them to your system When you click in the box and press a key the keyboard reacts using the settings currently specified by the sliders even if you have not yet applied the changes to the Windows environment To learn how to adjust keyboard parameters in DOS see Adjusting Keyboard Parameters in DOS in Chapter 17 of Upgrading and Repairing PCs 11th Edition which is available in electronic form on the disc included with this book Keyboard Key Numbers and Scan Codes When you press a key on the keyboard the processor built into the keyboard 8048 or 6805 type reads the keyswitch location in the keyboard matrix The processor then sends to the motherboard a serial packet of data containing the scan code for the key that was pressed This is called the Make code When the key is released a corresponding Break code is sent indicating to the motherboard that the key has been released The Break code is equivalent to the Make scan code plus 80h For example if the Make scan code for the A key is 1Eh the Break code would be 9Eh By using both Make and Break scan codes the system can determine whether a particular key has been held down and determine whether multiple keys are being pressed In AT type motherboards that use an 8042 type keyboard controller the 8042
33. ave enabled USB Legacy support in the BIOS or use the PS 2 connector from the transceiver to con nect to the PS 2 keyboard port
34. ches as well as your game controller s Web site for tips and workarounds Wireless Input Devices For several years many manufacturers have offered cordless versions of mice and keyboards In most cases these devices have used either infrared or short range radio transceivers to attach to standard serial or PS 2 ports with matching transceivers located in the mouse or keyboard Wireless input devices are designed to be easier to use in cramped home office environments and where a large screen TV monitor device is used for home entertainment and computing Many manufacturers including Microsoft Logitech and second tier vendors offer bundled kits that include a wireless keyboard and mouse which share a transceiver Because many of these keyboards and mice have the latest features including programmable keys multimedia and Internet access keys and optical sensors these wireless combos are often the top of the line products from a given vendor and are often less expensive than buying the keyboard and mouse separately Wireless Input Devices Chapter 18 1053 How Wireless Input Devices Work The three major technologies used by wireless input devices are as follows E Infrared IR E Proprietary radio frequency E Bluetooth All three technologies use a transceiver connected to the PS 2 or USB ports on the computer Because many wireless transceivers are designed for use with a mouse and keyboard PS 2 compatible versions
35. chnology that makes up a typical PC keyboard is very interesting This section focuses on all the aspects of keyboard technology and design including the keyswitches the interface between the keyboard and the system the scan codes and the keyboard connectors Keyswitch Design Today s keyboards use any one of several switch types to create the action for each key Most key boards use a variation of the mechanical keyswitch A mechanical keyswitch relies on a mechanical momentary contact type switch to make the electrical contact that forms a circuit Some high end keyboards use a more sophisticated design that relies on capacitive switches This section discusses these switches and the highlights of each design The most common type of keyswitch is the mechanical type available in the following variations E Pure mechanical E Rubber dome E Foam element E Membrane Pure Mechanical Switches The pure mechanical type is just that a simple mechanical switch that features metal contacts in a momentary contact arrangement The switch often includes a tactile feedback mechanism consisting of a clip and spring arrangement designed to give a clicky feel to the keyboard and offer some resis tance to the keypress see Figure 18 3 Keytop TN LAMA X wt aa TT Contacts Figure 18 3 A typical mechanical switch used in older NMB keyboards As the key is pressed the switch pushes down on the contacts to make the connectio
36. come in many shapes and sizes from many manufacturers Some have taken the standard mouse design and turned it upside down creating the trackball In the trackball devices you move the ball with your hand directly rather than moving the unit itself Trackballs were originally found on arcade video games such as Missile Command but have become popular with users who have limited desk space In most cases the dedicated trackballs have a much larger ball than would be found on a stan dard mouse Other than the orientation and perhaps the size of the ball a trackball is identical to a mouse in design basic function and electrical interface Like many recent mice trackballs often come in ergonomic designs and the more recent models even use the same optical tracking mechanisms used by the latest Microsoft and Logitech mice The largest manufacturers of mice are Microsoft and Logitech these two companies provide designs that inspire the rest of the industry and each other and are popular OEM choices as well as retail brands Even though mice can come in different varieties their actual use and care differ very little The standard mouse consists of several components E A housing that you hold in your hand and move around on your desktop E A method of transmitting movement to the system either ball roller or optical sensors E Buttons two or more and often a wheel or toggle switch for making selections a An interface for connecting the mouse
37. d failures due to running out of battery power Some vendors provide software that gives users an onscreen warning when batteries run low Furthermore when using an optical wireless mouse you should try working on brighter or whiter 1056 Chapter 18 Input Devices surfaces Many optical mice adjust their sensors based on the illumination of the surface which is why you might see the light in the mouse change intensity The less intense the internal LED operates the less battery power being used E Location The range of wireless devices can vary from 6 ft with conventional RF devices to as much as 30 ft with Bluetooth based devices Consider where the device will be used before making your purchase For instance in an office where multiple devices might be used at the same time a close range device might be more desirable to avoid crosstalk among devices On the other hand the home user who wants to sit away from the screen while maintaining con trol might want an extended range making Bluetooth enabled devices a better choice E User experience Different users will have different expectations of wireless input devices but in general the more a wireless input device acts like its wired siblings the better The fact that a device is wireless should not compromise its functionality If things such as reliability connection or driver problems hinder proper usage the device isn t worth using Hardcore gamers who need the faste
38. ecially for USB 1044 Chapter 18 Input Devices E USB mice and pointing devices similar to all other USB devices are hot swappable If you like to use a trackball and your computing partners prefer mice you can just lean over and unplug the other users pointing device and plug in your own or move it from PC to PC You can t do that with the other port types MH USB mice can be attached to a USB hub such as the hubs contained in some USB keyboards as well as standalone hubs Using a hub makes attaching and removing your mouse easy without crawling around on the floor to reach the back of the computer Many computers now have front mounted USB ports letting you easily attach and remove a USB mouse without the use of an external hub Although the early USB mice were decidedly on the premium end of the price scale low cost USB mice are now available for less than 20 If you want to use a USB mouse at an MS DOS prompt in Windows safe mode or in some other envi ronment outside of normal Windows 98 or later make sure that USB Legacy mode is enabled in your PC s BIOS as discussed earlier in this chapter Legacy mode enables non USB aware systems to recog nize a USB keyboard and mouse A fourth type of connection the bus mouse referred to by Microsoft as the Inport mouse used a dedi cated adapter card and is now obsolete For more information about the bus mouse see Chapter 17 of Upgrading and Repairing PCs 11th Edit
39. em both simultaneously because odd and even ports use different interrupts The best way around these interrupt conflicts is to make sure no two devices use the same interrupt Serial port adapters are available for adding COM3 and COM64 serial ports that do not share the inter rupts used by COM1 and COM2 These boards enable the new COM ports to use other normally available interrupts such as IRQs 10 11 12 15 and 5 I never recommend configuring a system with shared ISA interrupts it is a sure way to run into problems later However interrupts used by PCI boards can be shared if you use Windows 95 OSR 2 x Windows 98 Windows Me Windows 2000 or Windows XP with recent chipsets that support a feature called IRQ steering See PCI Interrupts p 370 If you suspect an interrupt problem with a bus type mouse you can use the Device Manager built into Windows which is accessible from the System control panel See Operating System Diagnostics p 1299 The Device Manager in Windows 9x Me 2000 XP is part of the Plug and Play PnP software for the system and it is usually 100 accurate on PnP hardware Although some of these interrupt reporting programs can have problems most can easily identify the mouse IRQ if the mouse driver has been loaded After the IRQ is identified you might need to change the IRQ setting of the bus mouse adapter or one or more other devices in your system so that everything works together properly If yo
40. eparate numeric keypad Num Lock On IBM systems that support the Enhanced keyboard when the system detects the keyboard on powerup it enables the Num Lock feature and the light goes on If the system detects an older 84 key AT type keyboard it does not enable the Num Lock function because these keyboards do not have cursor keys separate from the numeric keypad When the Enhanced keyboards first appeared in 1986 many users including me were irritated to find that the numeric keypad was automatically enabled every time the system booted Most system manufacturers subsequently began integrating a function into the BIOS setup that enabled you to specify the Num Lock status imposed during the boot process Some users thought that the automatic enabling of Num Lock was a function of the Enhanced key board because none of the earlier keyboards seemed to operate in this way Remember that this func tion is not really a keyboard function but instead a function of the motherboard ROM BIOS which identifies an Enhanced 101 key unit and turns on the Num Lock as a favor In systems with a BIOS that can t control the status of the numeric keypad you can use the DOS 6 0 or higher version NUMLOCK parameter in CONFIG SYS to turn Num Lock on or off as desired Some versions of Windows particularly Windows NT and Windows 2000 but not Windows XP disable Num Lock by default 1022 Chapter 18 Input Devices Keyboard Technology The te
41. er dome causing it to resist and then collapse all at once much like the top of an oil can As the rubber dome collapses the user feels the tactile feedback and the carbon button makes contact between the circuit board traces below When the key is released the rubber dome re forms and pushes the key back up The rubber eliminates the need for a spring and provides a reasonable amount of tactile feedback without any special clips or other parts Rubber dome switches use a carbon button because it resists corrosion and has a self cleaning action on the metal contacts below The rubber domes themselves are formed into a sheet that completely protects the contacts below from dirt dust and even minor spills This type of switch design is the simplest and it uses the fewest parts This made the rubber dome keyswitch very reliable for several years However its relatively poor tactile feedback has led most keyboard manufacturers to switch to the membrane switch design covered in the next section Membrane Switches The membrane keyswitch is a variation on the rubber dome type using a flat flexible circuit board to receive input and transmit it to the keyboard microcontroller Industrial versions of membrane boards use a single sheet for keys that sits on the rubber dome sheet for protection against harsh environ ments This arrangement severely limits key travel For this reason flat surface membrane keyboards are not considered usable for normal t
42. er major method of motion detection is optical Some of the early mice made by Mouse Systems and a few other vendors used a sensor that required a special grid marked pad Although these mice were very accurate the need to use them with a pad caused them to fall out of favor Microsoft s IntelliMouse Explorer pioneered the return of optical mice The IntelliMouse Explorer and the other new style optical mice from Logitech and other vendors use optical technology to detect movement and they have no moving parts of their own except for the scroll wheel and buttons on top Today s optical mice need no pad they can work on virtually any surface This is done by upgrading the optical sensor from the simple type used in older optical mice to a more advanced CCD charge coupled device This essentially is a crude version of a video camera sensor that detects move ment by seeing the surface move under the mouse An LED is used to provide light for the sensor 1040 Chapter 18 Input Devices The IntelliMouse Explorer revolutionized the mouse industry first Logitech then virtually all other mouse makers including both retail and OEM suppliers have moved to optical mice for most of their product lines offering a wide variety of optical mice in most price ranges Figure 18 11 shows the essential features of a typical optical mouse CCD camera LED to illuminate surface Figure 18 11 The bottom of the Logitech iFeel optical mouse
43. eral users however are highly resistant to change and these designs have yet to signifi cantly displace the standard keyboard layout If you don t want to spend big bucks on the more radi cal ergonomic keyboards but want to give yourself at least limited protection from RSI consider keyboards with a built in wrist rest or add a gel based wrist rest to your current keyboard These pro vide hand support without making you learn a modified or brand new keyboard layout USB Keyboards with Hubs Some of the latest USB keyboards feature a built in USB hub designed to add two or more USB ports to your system Even though this sounds like a good idea keep in mind that a keyboard based hub won t provide additional power to the USB connectors Powered hubs work better with a wider variety of devices than unpowered hubs do I wouldn t choose a particular model based solely on this feature although if your keyboard has it and your devices work well when plugged into it that s great I d rec ommend that you use this type of keyboard with your USB mouse or other devices that don t require much power Bus powered devices such as scanners and Webcams should be connected to a self powered hub or directly to the USB ports built in to the computer USB keyboards and mice correspond to the USB 1 1 standard but can also be connected to the faster USB 2 0 ports on the latest systems Multimedia and Web Enabled Keyboards As I discussed earlier in this cha
44. ersions One of the many useful features of the IBM Lexmark enhanced keyboard now manufactured by Unicomp is removable keycaps This permits the replacement of broken keys and provides access for easier cleaning Also with clear keycaps and paper inserts you can customize the keyboard Keyboard templates are also available to provide specific operator instructions 104 Key Windows 9x Me 2000 XP Keyboard With the introduction of Windows 95 a modified version of the standard 101 key design created by Microsoft appeared called the 104 key Windows keyboard If you are a touch typist as I am you probably really hate to take your hands off the keyboard to use a mouse Windows 9x and newer versions make this even more of a problem because they use both the right and left mouse buttons the right button is used to open shortcut menus Many new keyboards especially those in portable computers include a variation of the IBM TrackPoint or the Cirque GlidePoint pointing devices discussed later in this chapter which enable touch typists to keep their hands on the keyboard even while moving the pointer However another alternative is available that can help When Microsoft released Windows 95 it also introduced the Microsoft Natural Keyboard which implemented a revised keyboard specification that added three new Windows specific keys to the keyboard The Microsoft Windows keyboard specification which has since become a de facto industry stand
45. ery power needed for wireless use Logitech offers several wireless trackball models that use radio frequency transceivers for details of how this technology works see the section Wireless Input Devices later in this chapter Trackballs use the same drivers and connectors as conventional mice For basic operations the operating system supplied drivers will work but you should use the latest version of the vendor supplied drivers to achieve maximum performance with recent models Pointing Devices Chapter 18 1051 Cleaning and Troubleshooting Trackballs Trackball troubleshooting is similar to mouse troubleshooting For issues other than cleaning the trackball see the section Mouse Troubleshooting earlier in this chapter Because trackballs are moved by the user s hand rather than by rolling against a tabletop or desktop they don t need to be cleaned as often as mouse mechanisms do However occasional cleaning is recom mended especially with trackballs that use roller movement detection mechanisms If the trackball pointer won t move skips or drags when you move the trackball try cleaning the trackball mechanism Trackballs can be held into place by a retaining ring an ejection tab or simply by gravity Check the vendor s Web site for detailed cleaning instructions if your trackball didn t come with such instruc tions Swabs and isopropyl alcohol are typically used to clean the trackball and rollers o
46. es affordable for almost everyone If you re plan ning to use a computer to drive a big screen TV or as a presentation unit consider Bluetooth enabled devices available from Microsoft Logitech and others because of their longer range up to 10 meters or 33 ft Power Management Features of Wireless Input Devices A wireless mouse is useless if its batteries fail so several vendors of wireless products have developed sophisticated power management features to help preserve battery life especially with optical mice which use power eating LEDs to illuminate the mousing surface For example the Logitech Cordless MouseMan Optical s LED sensor has four operating modes as shown in Table 18 5 Table 18 5 Logitech Cordless MouseMan Optical Power Management Mode LED Flashing Rate Notes Normal 1 500 per second Used only when mouse is being moved across a surface Glow 1 000 per second Used when mouse stops moving Strobe 10 per second Mouse not moved for more than 2 minutes Flash 2 per second Mouse not moved for more than 10 minutes Wireless keyboards are activated only when you press a key or use the scroll wheel available on some models so they tend to have longer battery lives than mice Conventional ball type mice also have longer battery lives than optical mice but the convenience and accuracy of optical mice outweigh battery life issues for most users Wireless Pointing Device Issues Before you invest in wireless pointing
47. es are those of this chip IRQ12 is an interrupt that is usually free on most systems but if you use a USB mouse you can probably disable the mouse port to make IRQ12 available for use by another device Pointing Devices Chapter 18 1043 Hybrid Mice Hybrid mice are those designed to plug into two types of ports Although a few low cost mice sold at retail are designed to plug into either the serial port or the PS 2 port most mice on the retail market today are designed to plug into either the PS 2 port or the USB port These combination mice are more flexible than the mice typically bundled with systems which are designed to work only with the PS 2 or USB port to which they attach Circuitry in a hybrid mouse automatically detects the type of port to which it is connected and configures the mouse automatically Serial PS 2 hybrid mice usually come with a mini DIN connector on the end of their cable and an adapter that converts the mini DIN to a 9 or 25 pin serial port connector although the reverse is sometimes true on early examples of these mice PS 2 USB mice usually come with the USB connector on the end of their cable and include a mini DIN PS 2 adapter as shown in Figure 18 13 PS 2 mouse port N PS 2 USB lt mouse adapter __ USB mouse Figure 18 13 A typical USB mouse with a PS 2 adapter Sometimes people use adapters to try to connect a serial mouse to a motherboard mouse port or a motherboard mouse
48. es provided in the Technical Reference section on the disc to determine which keyswitch is the culprit By removing the keycap of the offending key and cleaning the switch you often can solve the problem For a simple test of the motherboard keyboard connector you can check voltages on some of the pins Using Figure 18 8 which was shown earlier in the chapter as a guide measure the voltages on various pins of the keyboard connector To prevent possible damage to the system or keyboard turn off the power before disconnecting the keyboard Then unplug the keyboard and turn the power back on Make measurements between the ground pin and the other pins according to Table 18 2 shown earlier in the chapter If the voltages are within these specifications the motherboard keyboard circuitry is probably okay If your measurements do not match these voltages the motherboard might be defective Otherwise the keyboard cable or keyboard might be defective If you suspect that the cable is the problem the easiest thing to do is replace the keyboard cable with a known good one If the system still does not work normally you might have to replace the entire keyboard or the motherboard In many newer systems the motherboard s keyboard and mouse connectors are protected by a fuse that can be replaced Look for any type of fuse on the motherboard in the vicinity of the keyboard or mouse connectors Other systems might have a socketed keyboard controller chi
49. ess products use proprietary radio transceivers the Bluetooth wireless standard can now be used by some keyboards and mice such as Microsoft s pioneering Wireless Optical Desktop mouse and keyboard bundle or the Wireless IntelliMouse Explorer for Bluetooth Logitech also offers a Bluetooth enabled input device its Cordless Presenter handheld pointing device Bluetooth enabled devices have an effective range of up to 30 ft and might be compatible with other brands of devices that are also Bluetooth enabled Wireless Input Devices Chapter 18 1055 gt gt For more information about Bluetooth see Chapter 20 Local Area Networking p 1101 Having used both IR and RF types of wireless devices I can tell you that a radio frequency input device beats an infrared input device hands down for use at home or in a small one or two person office Because infrared requires an unobstructed direct line between the transceivers when I used an infrared keyboard pointing stick combination at a client site I was constantly re aiming the keyboard at the transceiver to avoid losing my signal When I used a radio mouse on the other hand there were no line of sight issues to worry about Historically the only advantage to infrared was cost but the problems of reliability in my mind outweigh any cost savings Additionally a wide range of prices for RF wireless products including attractive keyboard and mouse combinations make RF input devic
50. et the job done with little risk of removing your keytops You also can use canned compressed air to blow the dust and dirt out instead of using a vacuum Before you dust a keyboard with the compressed air turn the keyboard upside down so that the par ticles of dirt and dust collected inside can fall out On all keyboards each keycap is removable which can be handy if a key sticks or acts errati cally For example a common problem is a key that does not work every time you press it This problem usually results from dirt collecting under the key An excellent tool for removing key caps on almost any keyboard is the U shaped chip puller included in many computer tool kits Simply slip the hooked ends of the tool under the keycap squeeze the ends together to grip the underside of the keycap and lift up IBM sells a tool designed specifically for removing keycaps from its keyboards but the chip puller works even better After removing the cap spray some compressed air into the space under the cap to dislodge the dirt Then replace the cap and check the action of the key Caution When you remove the keycaps be careful not to remove the spacebar on the original 83 key PC and the 84 key Altype keyboards This bar is difficult to reinstall The newer 101 key units use a different wire support that can be removed and replaced much more easily When you remove the keycap on some keyboards you are actually detaching the entire key from the k
51. evolutionary TrackPoint pointing device TrackPoint refers to a small stick mounted between the G H and B keys This device was first featured on the IBM ThinkPad laptop systems although the keyboards are now sold for use on other manufacturers PCs The technology is being licensed to many other manu facturers including Toshiba Other manufacturers of high quality keyboards that are similar in feel to the IBM Lexmark Unicomp units are Alps Lite On NMB Technologies and the revived Northgate designs sold under the Avant Prime and Avant Stellar names by Creative Vision Technologies These keyboards have excellent tactile feedback with a positive click sound They are my second choice after a Unicomp unit Pointing Devices The mouse was invented in 1964 by Douglas Englebart who at the time was working at the Stanford Research Institute SRI a think tank sponsored by Stanford University The mouse was officially called an X Y Position Indicator for a Display System Xerox later applied the mouse to its revolution ary Alto computer system in 1973 At the time unfortunately these systems were experimental and used purely for research In 1979 several people from Apple including Steve Jobs were invited to see the Alto and the soft ware that ran the system Steve Jobs was blown away by what he saw as the future of computing which included the use of the mouse as a pointing device and the graphical user interface GUI it operated Ap
52. ew IBM cap much more easily than you can grip the designs used by others Pointing Devices Chapter 18 1049 The other difference between the TrackPoint II and III IV from IBM is in the control software IBM added routines that implement a subtle technique Selker calls negative inertia which is marketed under the label QuickStop response This software not only takes into account how far you push the pointer in any direction but also how quickly you push or release it Selker found that this improved software and the sandpaper cap enables people to make selections up to 8 faster TrackPoint IV includes an extra scroll button as well as the ability to press the TrackPoint nub to select as if using the left mouse button These new features make the TrackPoint even better to use The bottom line is that anyone who touch types should strongly consider only portable systems that include an IBM licensed TrackPoint device such as Toshiba TrackPoints are far superior to other pointing devices such as the touch pads because the TrackPoint is faster to use you don t have to take your hands off the keyboard s home row easier to adapt to especially for speedy touch typists and far more precise It takes some getting accustomed to but the benefits are worth it The benefits of the TrackPoint are not limited to portable systems however If you use a notebook computer with TrackPoint like I do you can have the same features on
53. eyswitch Be careful during the removal or reassembly of the keyboard otherwise you ll break the switch The classic IBM Lexmark type keyboards now made by Unicomp use a removable key cap that leaves the actual key in place enabling you to clean under the keycap without the risk of breaking the switches If your keyboard doesn t have removable keycaps consider using cleaning wands with soft foam tips to clean beneath the keytops Spills can be a problem too If you spill a soft drink or cup of coffee into a keyboard you do not necessarily have a disaster Many keyboards that use membrane switches are spill resistant However you should immediately or as soon as possible disconnect the keyboard and flush it out with dis tilled water Partially disassemble the keyboard and use the water to wash the components See Keyboard Disassembly in the Technical Reference section of the disc accompanying this book for disassembly instructions If the spilled liquid has dried soak the keyboard in some of the water for a while When you are sure the keyboard is clean pour another gallon or so of distilled water over it and through the keyswitches to wash away any residual dirt After the unit dries completely it should be perfectly functional You might be surprised to know that drenching your keyboard with water does not harm the components Just make sure you use distilled water which is free from residue or mineral content bottled water is not
54. hand Microsoft IntelliMouse Explorer and movements such as when playing games Optical series Dual sensors Faster speed and accuracy especially Logitech MouseMan Dual Optical for gaming Optical mice similar to traditional ball type mice are available as corded or cordless models Cordless ball type mice are usually much larger than ordinary mice because of the need to find room for both the bulky ball mechanism and batteries but cordless optical mice are about the same size as high end corded mice The cable can be any length but it is typically between 4 and 6 feet long Mice are also available in a cordless design which uses either infrared or RF transceivers to replace the cable A receiver is plugged into the mouse port while the battery powered mouse contains a compatible transmitter Tip If you have a choice on the length of cable to buy get a longer one This allows easier placement of the mouse in rela tion to your computer Extension cables can be used if necessary After the mouse is connected to your computer it communicates with your system through the use of a device driver which can be loaded explicitly or built into the operating system software For exam ple no separate drivers are necessary to use a mouse with Windows or OS 2 but using the mouse with most DOS based programs requires a separate driver to be loaded from the CONFIG SYS or AUTOEXEC BAT file Regardless of whether it is built in the driver translate
55. have two cables one for the mouse port and one for the keyboard port A USB compatible transceiver needs only one USB port to handle both devices if the system supports USB Legacy keyboard func tions The transceiver attached to the computer draws its power from the port The transceiver receives signals from the transceiver built in to the mouse or keyboard These devices require batteries to function therefore a common cause of wireless device failure is battery run down Early generations of wireless devices used unusual battery types but most recent products use off the shelf alkaline AA or AAA batteries Rechargeable batteries are usually not supported although Logitech s MX 700 has built in rechargeable batteries and a transceiver that doubles as a charger Although all three technologies rely on battery power the similarities end there IR devices have a relatively short range 12 ft maximum and must have a clear line of sight between the input device and transceiver Anything from a Mountain Dew can to a sheet of paper can block the IR signal from reaching the trans ceiver assuming you re aiming the transmitter built in to your input device correctly in the first place Some late model IR devices have transceivers that can receive signals through a relatively wide 120 range but this technology is much more temperamental than the others and has been abandoned by most vendors Figure 18 15 shows how range and line of sight issues
56. he most obvious one is in the rubber cap The IBM TrackPoint II and Toshiba Accupoint caps are made from silicone rubber which is grippy and works well in most situations However if the user has greasy fingers the textured surface of the rubber can absorb some of the grease and become slippery Cleaning the cap and the user s hands solves the problem but it can be annoying at times The TrackPoint III IV caps are made from a different type of rubber which Selker calls plastic sandpaper This type of cap is much more grippy and does not require cleaning except for cosmetic purposes I have used both types of caps and can say for certain that the TrackPoint III IV cap is superior Note Because the Accupoint device used in the Toshiba notebooks is licensed from IBM it uses the same hardware a pressure transducer called a strain gauge and takes the same physical caps ordered a set of the TrackPoint Ill caps and installed them on my Toshiba portable systems which dramatically improved the grip You can get these caps by ordering them from IBM Parts directly or from others who sell IBM parts such as Compu lock www compu Lock com The cost is under 15 for a set of four plastic sandpaper red caps Replacing the cap is easy grab the existing cap with your fingers and pull straight up it pops right off Then push on the new red IBM TrackPoint III IV cap in its place You will thank me when you feel how you can grip the n
57. ion which is included on the disc supplied with this book Mouse Troubleshooting If you are experiencing problems with your mouse you need to look in only two general places hardware or software Because mice are basically simple devices looking at the hardware takes very little time Detecting and correcting software problems can take a bit longer however To troubleshoot wireless mice see Troubleshooting Wireless Input Devices later in this chapter Cleaning Your Mouse If you notice that the mouse pointer moves across the screen in a jerky fashion it might be time to clean your mouse For a mouse with a roller ball this jerkiness is caused when dirt and dust become trapped around the mouse s ball and roller assembly thereby restricting its free movement From a hardware perspective the mouse is a simple device so cleaning it is easy The first step is to turn the mouse housing over so that you can see the ball on the bottom Notice that surrounding the ball is an access panel you can open Sometimes instructions indicate how the panel is to be opened Some off brand mice might require you to remove some screws to get at the roller ball Remove the panel to see more of the roller ball and the socket in which it rests If you turn the mouse back over the rubber roller ball should fall into your hand Take a look at the ball It might be gray or black but it should have no visible dirt or other contamination If it does wash
58. iproprietary LPX motherboards and all ATX series motherboards use these same connectors for space reasons Most Baby AT motherboards have a pin header type connector for the mouse port because most stan dard cases do not have a provision for the mini DIN mouse connector If that is the case an adapter cable is usually supplied with the system This cable adapts the pin header connector on the mother board to the standard mini DIN type connector used for the motherboard mouse Caution As mentioned in the Keyboard Mouse Interface Connectors section earlier in this chapter the mini DIN sockets used for both keyboard and mouse connections on many systems are physically and electrically interchangeable but the data packets they carry are not Be sure to plug each device into the correct socket otherwise neither will function correctly Don t panic if you mix them up though They are electrically identical to each other so you can t damage the ports or the devices Connecting a mouse to the built in mouse port is the best method of connection on systems that don t have USB ports because you do not sacrifice any of the system s interface slots or any serial ports and the performance is not limited by the serial port circuitry The standard resource usage for a motherboard or PS 2 mouse port is IRQ12 as well as I O port addresses 60h and 64h Because the motherboard mouse port uses the 8042 type keyboard controller chip the port address
59. is available in several variations but all are basically the same electrically and all can be interchanged IBM with its Lexmark keyboard and printer spinoff and Unicomp which now produces these keyboards have produced a number of keyboard models including versions with built in pointing devices and new ergonomic layouts With the replacement of the Baby AT mother board and its five pin DIN an acronym for Deutsches Institut fiir Normung e V keyboard connector by ATX motherboards which use the six pin mini DIN keyboard connector virtually all keyboards on the market today come with cables for the six pin mini DIN connector introduced on the IBM PS 2s Although the connectors might be physically different the keyboards are not and you can either interchange the cables or use a cable adapter to plug one type into the other some keyboards you can Keyboards Chapter 18 1017 buy at retail include the adapter in the package See the section Keyboard Mouse Interface Connectors and Figure 18 8 later in this chapter for the physical and electronic details of these con nectors Many keyboards now include both the standard mini DIN as well as USB connectors for max imum flexibility when attaching to newer systems See the section USB Keyboards later in this chapter for details on connecting keyboards via USB The 101 key keyboard layout can be divided into the following four sections E Typing area E Cursor and screen con
60. keyboards often use an 8049 version that has built in ROM or other microcontroller chips compatible with the 8048 or 8049 For example in its Enhanced keyboards IBM has always used a custom version of the Motorola 6805 processor which is compatible with the Intel chips The keyboard s built in processor reads the key matrix debounces the keypress signals converts the keypress to the appropriate scan code and transmits the code to the motherboard The processors built into the keyboard contain their own RAM possibly some ROM and a built in serial interface In the original PC XT design the keyboard serial interface is connected to an 8255 Programmable Peripheral Interface PPI chip on the motherboard of the PC XT This chip is connected to the interrupt controller IRQ1 line which is used to signal to the system that keyboard data is available The data is then sent from the 8255 to the processor via I O port address 60h The IRQ1 signal causes the main system processor to run a subroutine INT 9h that interprets the keyboard scan code data and decides what to do In an AT type keyboard design the keyboard serial interface is connected to a special keyboard controller on the motherboard This controller was an Intel 8042 Universal Peripheral Interface UPI slave micro controller chip in the original AT design This microcontroller is essentially another processor that has its own 2KB of ROM and 128 bytes of RAM An 8742 version that uses eras
61. l the Windows key combinations used with the 104 key keyboard Table 18 1 Windows 9x Me 2000 XP Key Combinations Key Combination Resulting Action WIN R Runs dialog box WIN M Minimize All Shift WIN M Undo Minimize All WIN D Minimize All or Undo Minimize All WIN F1 Help WIN E Starts Windows Explorer WIN F Find Files or Folders Ctrl WIN F Find Computer WIN Tab Cycles through taskbar buttons WIN Break Displays System Properties dialog box Application key Displays a context menu for the selected item The preceding keystroke combinations work with any manufacturer s 104 key keyboard but users of certain Microsoft 104 key keyboards can enhance their keyboard use further by installing the IntelliType Pro software supplied by Microsoft with the keyboard The Windows keys are not mandatory when running Windows In fact preexisting standard key com binations perform the same functions as these newer keys I also have noticed that only power users Keyboards Chapter 18 1019 wanting to work as efficiently as possible by keeping their hands on the keyboard and off the mouse primarily use these combinations The Windows keyboard specification requires that keyboard makers increase the number of trilograms in their keyboard designs A trilogram is a combination of three rapidly pressed keys that perform a special function such as Ctrl Alt Delete Designing a keyboard so that the switch matrix correctly reg isters the
62. le an IR mouse early versions of RF products had a high potential for interference from other devices and from other devices in use in the same room because of a limited range of channels For example early Logitech wireless MouseMan prod ucts required the user to manually select the channel used by the transceiver and mouse If more than six users in a small room had wireless devices interference was practically inevitable and user error could lead to a user s mouse movements showing up on the wrong computer screen Fortunately improvements in frequency bands used and automatic tuning have enabled all users of a par ticular type of device to avoid interference with other electronic devices or with each other For example Logitech s current line of wireless products uses its patented Palomar technology Although the 27MHz frequency used by Palomar has become a de facto standard for most recent wireless input devices it s also used by Microsoft and IBM for their wireless products Logitech allows users to enable a digital security feature that uses one of more than 4 000 unique codes to prevent accidentally activating another com puter with a wireless device or signal snooping by another user Most vendors use similar technology but might use a much smaller number of codes The range of 27MHz RF devices is short about 6 ft but the transmitter can be located behind the computer or under the desk without loss of signal Although most wirel
63. ling and other advanced functions It s available in various colors and separate models for Windows based PCs and Macs 1052 Chapter 18 Input Devices Input Devices for Gaming Originally game players on the PC used the arrow keys or letter keys on the keyboard to play all types of games As you can imagine this limited the number and type of games that could be played on the PC Analog Joysticks and the Game Port As video standards improved making games more realistic input devices made especially for game play also became more and more popular The first joysticks made for the IBM PC were similar to joy sticks made for its early rival the Apple II series Both the IBM and Apple II joysticks were analog devices that lacked much of the positive feedback game players were accustomed to from the Atari 2600 Commodore 64 or arcade joysticks These joysticks also required frequent recalibration to work properly and were far from satisfactory to hardcore game players Also these devices required their own connector the 15 pin game port The game port found its way onto many sound cards as well as onto multi I O cards made for ISA and VL Bus systems Even though joysticks began to add better features including spring action video game style gamepads and flight control options the analog nature and slow speed of the gameport began to restrict performance as CPU speeds climbed above 200MHz and high speed AGP and PCI video cards m
64. mouse and replacing the hand on the keyboard takes approximately 1 75 seconds If you type 60wpm that can equal nearly two lost words per minute not including the time lost while 1048 Chapter 18 Input Devices you regain your train of thought Almost all this time can be saved each time you use TrackPoint to move the pointer or make a selection click or double click The combination of the buttons and the positioning knob also enable you to perform drag and drop functions easily IBM s research also found that people can get up to 20 more work accomplished using the TrackPoint instead of a mouse especially when the application involves a mix of typing and pointing activities such as with word processing spreadsheets and other typical office applications In usabil ity tests with the TrackPoint III IBM gave a group of desktop computer users a TrackPoint and a tradi tional mouse After two weeks 80 of the users had unplugged their mice and switched solely to the TrackPoint device Selker is convinced as am I that the TrackPoint is the best pointing solution for both laptop and desktop systems Another feature of the TrackPoint is that a standard mouse can be connected to the system at the same time to enable dual pointer use This setup not only enables a single person to use both devices but also enables two people to use the TrackPoint and the mouse simultaneously to move the pointer on the screen The first pointing device
65. n Mechanical switches are very durable usually have self cleaning contacts and are normally rated for 20 million keystrokes which is second only to the capacitive switch in longevity They also offer excellent tactile feedback Despite the tactile feedback and durability provided by mechanical keyswitch keyboards they have become much less popular than membrane keyboards discussed later in this chapter In addition many companies that produce keyboards that use mechanical keyswitches either use them for only a few of their high priced models or have phased out their mechanical keyswitch models entirely With the price of keyboards nose diving along with other traditional devices such as mice and drives the pressure on keyboard makers to cut costs has led many of them to abandon or de emphasize mechanical keyswitch designs in favor of the less expensive membrane keyswitch Keyboard Technology Chapter 18 1023 The Alps Electric mechanical keyswitch is used by many of the vendors who produce mechanical switch keyboards including Alps Electric itself Other vendors who use mechanical keyswitches for some of their keyboard models include Adesso Inc ww adesso com Avant Prime and Stellar revivals of the classic Northgate keyboards and available from Ergonomic Resources www ergo 2000 com Kinesis www kinesis ergo com SIIG ww siig com and Focus ww focustaipei com Many of these vendors sell through the OEM market so
66. n older systems the 8042 keyboard controller is also used by the system to control the A20 memory address line which provides access to system memory greater than 1MB More modern motherboards typically incorporate this functionality directly into the motherboard chipset The AT keyboard con nector was renamed the PS 2 port after the IBM PS 2 family of systems debuted in 1987 That was 1028 Chapter 18 Input Devices the time when the connector changed in size from the DIN to the min DIN and even though the sig nals were the same the mini DIN version became known from that time forward as the PS 2 port Keyboards connected to a USB port work in a surprisingly similar fashion to those connected to con ventional DIN or mini DIN PS 2 ports after the data reaches the system Inside the keyboard a vari ety of custom controller chips is used by various keyboard manufacturers to receive and interpret keyboard data before sending it to the system via the USB port Some of these chips contain USB hub logic to enable the keyboard to act as a USB hub After the keyboard data reaches the USB port on the system the USB port routes the data to the 8042 compatible keyboard controller where the data is treated as any other keyboard information This process works very well after a system has booted into Windows But what about users who need to use the keyboard at a command prompt or within the BIOS configuration routine As discussed earlie
67. nicomp Unicomp maintains an extensive selection of more than 1 400 Lexmark and IBM keyboard models and continues to develop and sell a wide variety of traditional and customized models including keyboards that match the school colors of several universities Unicomp sells keyboards directly via its Web site at ww pckeyboard com My personal favorite is the black EnduraPro 104 Note See the section Replacement Keyboards in Chapter 17 of Upgrading and Repairing PCs 1 Ith Edition on this book s disc for a listing of IBM keyboard and cable part numbers Some of the classic design IBM keyboards are available in the retail market under either the IBM or IBM Options brand name Items under the IBM Options program are sold direct by IBM s Web site www pc ibm com or through normal retail channels such as CompUSA and Computer Discount Warehouse CDW These items are also priced much more cheaply than items purchased as spare parts They include a full warranty and are sold as complete packages including cables Table 18 3 lists some of the IBM Options keyboards and part numbers even though the IBM Web site no longer offers these models they can be purchased from various online retailers Models marked with an are also available from Unicomp Table 18 3 IBM Options Keyboards Sold Retail Description Part Number IBM Enhanced keyboard cable w DIN plug 92G7454 IBM Enhanced keyboard cable w mini DIN plug 92G7453 IBM Enhanced
68. o attach the keyboard and power supply Although cross connecting the mini DIN connectors of a mouse and keyboard is a harmless annoy ance connecting a power supply to a keyboard socket can be disastrous USB keyboards use the Series A USB connector to attach to the USB port built into modern computers For more information on USB see Chapter 17 I O Interfaces from Serial and Parallel to IEEE 1394 and USB Keyboards with Special Features Several keyboards on the market have special features not found in standard designs These additional features range from simple things such as built in calculators clocks and volume control to more complicated features such as integrated pointing devices special character layouts shapes and even programmable keys Note In 1936 August Dvorak patented a simplified character layout called the Dvorak Simplified Keyboard DSK The Dvorak keyboard was designed to replace the common QWERTY layout used on nearly all keyboards available today The Dvorak keyboard was approved as an ANSI standard in 1982 but has seen limited use For a comparison between the Dvorak keyboard and the common QWERTY keyboard you most likely use see The Dvorak Keyboard in the Technical Reference section of the disc accompanying this book Ergonomic Keyboards A trend that began in the late 1990s is to change the shape of the keyboard instead of altering the character layout This trend has resulted in several so c
69. ore subject to corrosion on the foil conductor and the circuit board traces below When this happens the key strikes can become intermittent which can be frustrating Fortunately these keyboards are among the easiest to clean By disassem bling the keyboard completely you usually can remove the circuit board portion without removing each foam pad separately and expose the bottoms of all the pads Then you easily can wipe the cor rosion and dirt off the bottoms of the foam pads and the circuit board thus restoring the keyboard to a like new condition Unfortunately over time the corrosion problem will occur again I recom mend using some Stabilant 22a from D W Electrochemicals www stabilant com to improve the switch contact action and prevent future corrosion Because of such problems the foam element design is not used much anymore and has been superseded in popularity by the rubber dome design KeyTronicEMS the most well known user of this technology now uses a center bearing membrane switch technology in its keyboards so you are likely to encounter foam switch keyboards only on very old systems 1024 Chapter 18 Input Devices Rubber Dome Switches Rubber dome switches are mechanical switches similar to the foam element type but are improved in many ways Instead of a spring these switches use a rubber dome that has a carbon button contact on the underside As you press a key the key plunger presses on the rubb
70. ou have be sure you periodically download and install new mouse drivers Instead of the wheel used by Microsoft and Logitech IBM and other mouse vendors frequently use various types of buttons for scrolling Some inexpensive mice use a rocker switch but the most ele gant of the non wheel alternatives is IBM s ScrollPoint Pro which uses a pressure sensitive scroll stick Pointing Devices Chapter 18 1047 similar to the TrackPoint pointing device used on IBM s notebook computer and some PC keyboards made by IBM and Unicomp The scrollpointer in the center of the mouse enables you to smoothly scroll through documents without having to lift your finger to roll the wheel as you do on the Microsoft version which makes it much easier and more convenient to use Because no moving parts exist the ScrollPoint is also more reliable TrackPoint II 1I IV On October 20 1992 IBM introduced a revolutionary new pointing device called TrackPoint II as an integrated feature of its new ThinkPad 700 and 700C computers Often referred to as a pointing stick device TrackPoint II and its successors consist primarily of a small rubber cap that appears on the key board right above the B key between the G and H keys This was the first significant new pointing device since the mouse had been invented nearly 30 years earlier This device occupies no space on a desk does not have to be adjusted for left handed or right handed use has no moving part
71. ouch typing However they are ideal for use in extremely harsh environments Because the sheets can be bonded together and sealed from the elements membrane keyboards can be used in situations in which no other type could survive Many industrial applica tions use membrane keyboards for terminals that do not require extensive data entry but are used instead to operate equipment such as cash registers and point of sale terminals in restaurants Membrane keyswitches are no longer relegated to fast food or industrial uses though Over the last few years the membrane keyswitch used with conventional keyboard keytops has replaced the rubber dome keyswitch to become the most popular keyswitch used in low cost to mid range keyboards Inexpensive to make membrane switches have become the overwhelming favorite of low cost Pacific Rim OEM suppliers and are found in most of the keyboards you ll see at your local computer store or find inside the box of your next complete PC Although low end membrane keyswitches have a lim ited life of only 5 10 million keystrokes some of the better models are rated to handle up to 20 mil lion keystrokes putting them in the range of pure mechanical switches for durability see Figure 18 5 A few membrane switches are even more durable Cherry Corporation s G8x series keyboards use Cherry s own 50 million keystroke membrane switch design www cherrycorp com Membrane keyboards provide a firmer touch than rubber dome ke
72. ovided a real breakthrough No longer do you have to move the mouse pointer to click the scrollbar on the right side of your screen or take your hand off the mouse to use the arrow keys on the keyboard You just push or pull on the wheel This is a major convenience especially when browsing Web pages or working with word processing documents or spreadsheets Also unlike three button mice from other vendors the IntelliMouse s wheel button doesn t seem to get in the way and you are less likely to click it by mistake Although it took a while for software vendors to support the wheel improvements in application software and Windows support allow today s wheel mice to be fully useful with almost any recent or current Windows program Each vendor s mouse driver software offers unique features to enhance the basic operation of the mouse For example Logitech s MouseWare 9 7 driver enables you to select many uses for all three mouse buttons the scroll wheel is treated as a third mouse button as well as provides various options for how to scroll with each wheel click three lines six lines or one screen Microsoft s IntelliMouse driver offers a feature called ClickLock which allows you to drag items without holding down the pri mary mouse button In addition it offers a Universal Scroll feature that adds scrolling mouse support to applications that lack such support To get the most from whatever scrolling or other advanced feature mouse y
73. p 8042 type In that case you might be able to repair the motherboard keyboard circuit by replacing this chip Because these chips have ROM code in them you should get the replacement from the motherboard or BIOS manufacturer If the motherboard uses a soldered keyboard controller chip or a chipset that integrates the keyboard controller with other I O chips you ll need to replace the motherboard See the disc included with this book for a listing of the standard POST and diagnostic keyboard error codes used by some systems Keyboard Disassembly Although disassembling a keyboard is possible most likely you won t need or want to do that given the reasonable prices of keyboards If you do want to disassemble your keyboard see Keyboard Disassembly in the Technical Reference section of the disc accompanying this book Keyboard Troubleshooting and Repair Chapter 18 1035 Cleaning a Keyboard One of the best ways to keep a keyboard in top condition is periodic cleaning As preventive main tenance you should vacuum the keyboard weekly or at least monthly When vacuuming you should use a soft brush attachment this will help dislodge the dust Also note that many keyboards have keycaps that can come off easily Be careful when vacuuming otherwise you ll have to dig them out of the vacuum cleaner I recommend using a small handheld vacuum cleaner made for cleaning computers and sewing machines these have enough suction to g
74. ple promptly incorporated these features into what was to become the Lisa computer and lured away 15 20 Xerox scientists to work on the Apple system Although Xerox released the Star 8010 computer that used this technology in 1981 it was expensive poorly marketed and perhaps way ahead of its time Apple released the Lisa computer its first system that used the mouse in 1983 It was not a runaway success largely because of its 10 000 list price but by then Jobs already had Apple working on the low cost successor to the Lisa the Macintosh The Apple Macintosh was introduced in 1984 Although it was not an immediate hit the Macintosh has grown in popularity since that time Many credit the Macintosh with inventing the mouse and GUI but as you can see this technology was actually borrowed from others including SRI and Xerox Certainly the Macintosh and now Microsoft Windows and OS 2 have gone on to popularize this interface and bring it to the legion of Intel based PC systems Although the mouse did not catch on quickly in the PC marketplace today the GUIs for PC systems such as Windows practically demand the use of a mouse Therefore virtually every new system sold at retail comes with a mouse And because the mice packaged with retail systems are seldom high quality or up to date designs sooner or later most users are in the market for a better mouse or com patible pointing device 1038 Chapter 18 Input Devices Mice
75. pter many keyboards sold at retail and bundled with systems today feature fixed purpose or programmable hotkeys that can launch Web browsers run the Microsoft Media Player adjust the volume on the speakers change tracks on the CD player and so forth You need Windows 98 or later to use these hotkeys Windows Me Windows 2000 and Windows XP add additional support for these keyboards For the best results you should download the latest drivers for your keyboard and version of Windows from the keyboard vendor s Web site Keyboard Troubleshooting and Repair Keyboard errors are usually caused by two simple problems Other more difficult intermittent prob lems can arise but they are much less common The most frequent problems are as follows E Defective cables E Stuck keys Defective cables are easy to spot if the failure is not intermittent If the keyboard stops working alto gether or every keystroke results in an error or incorrect character the cable is likely the culprit Troubleshooting is simple especially if you have a spare cable on hand Simply replace the suspected cable with one from a known working keyboard to verify whether the problem still exists If it does the problem must be elsewhere 1034 Chapter 18 Input Devices If you remove the cable from the keyboard you can test it for continuity with a digital multimeter DMM DMMs that have an audible continuity tester built in make this procedure much easier
76. r and desktop keyboard integrated pointing devices although Cirque and Alps have both sold standalone versions of the touch pad for use as a mouse alternative on desktop systems Cirque s touch pads are now available at retail under the Fellowes brand name as well as direct from the Cirque Web site The Internet Touchpad also sold by Fellowes has enhanced software to support touch gestures has programmable hot buttons and includes other features to make Web surfing easier Although it has gained wide acceptance especially on portable computers touch pad technology can have many drawbacks for some users Operation of the device can be erratic depending on skin resis tance and moisture content The biggest drawback is that to operate the touch pad users must remove their hands from the home row on the keyboard which dramatically slows their progress In addition the operation of the touch pad can be imprecise depending on how pointy your finger or thumb is On the other hand if you re not a touch typist removing your hands from the keyboard to operate the touch pad might be easier than using a TrackPoint Even with their drawbacks touch pad pointing devices are still vastly preferable to using a trackball or a cumbersome external mouse with portable systems Unless you want to use a real mouse with a portable system I recommend you sit down with portable computers that have both touch pad and TrackPoint pointing devices Try them
77. r 102 Key Keyboard In 1986 IBM introduced the corporate Enhanced 101 key keyboard for the newer XT and AT models I use the word corporate because this unit first appeared in IBM s RT PC which was a RISC reduced instruction set computer system designed for scientific and engineering applications Keyboards with this design were soon supplied with virtually every type of system and terminal IBM sold Other com panies quickly copied this design which became the standard on Intel based PC systems until the introduction of the 104 key Windows keyboard in 1995 discussed later in this chapter The layout of this universal keyboard was improved over that of the 84 key unit with perhaps the exception of the Enter key which reverted to a smaller size The 101 key Enhanced keyboard was designed to conform to international regulations and specifications for keyboards In fact other com panies such as Digital Equipment Corporation DEC and Texas Instruments TI had already been using designs similar to the IBM 101 key unit The IBM 101 key units originally came in versions with and without the status indicator LEDs depending on whether the unit was sold with an XT or AT sys tem Now many other variations are available from which to choose including some with integrated pointing devices such as the IBM TrackPoint II pointing stick trackballs and touch pads and pro grammable keys useful for automating routine tasks The Enhanced keyboard
78. r bearings see the trackball s instructions for details 3M s Ergonomic Mouse Many PC users who grew up using joysticks on the older video games experienced some interface shock when they turned in their joysticks for mice And even long time mouse users nursing sore arms and elbows have wondered whether the mouse was really as ergonomic as it is sometimes claims to be 3M s solution developed late in 2000 is to keep the traditional ball type mouse positioning mecha nism but change the user interface away from the hockey puck soap bar design used for many years to a slanted handle that resembles a joystick see Figure 18 14 3M s Ergonomic Mouse originally called the Renaissance Mouse is available in two hand sizes and attaches to either the PS 2 port or USB port serial ports are not supported The single button on the top of the handle is a rocker switch push on the left side to left click and on the right side to right click The front handgrip pro vides scrolling support when the special Ergonomic Mouse driver software is installed Figure 18 14 The 3M Ergonomic Mouse combines an ergonomic shape with a standard mouse movement mechanism The Ergonomic Mouse enables the user to hold the pointing device with a handshake style hand and arm position 3M s Web site provides detailed ergonomic information to encourage the proper use of the Ergonomic Mouse which comes with software to support scrol
79. r in this chapter USB Legacy support must be enabled in the BIOS A BIOS with USB Legacy sup port is capable of performing the following tasks E Configure the host controller E Enable a USB keyboard and mouse E Set up the host controller scheduler E Route USB keyboard and mouse input to the 8042 Keyboard Controller Systems with USB Legacy support enabled use the BIOS to control the USB keyboard until a supported operating system is loaded At that point the USB host controller driver in the operating system takes control of the keyboard by sending a command called StopBIOS to the BIOS routine that was manag ing the keyboard When Windows shuts down to MS DOS the USB host controller sends a command called StartBIOS to restart the BIOS routine that manages the keyboard When the BIOS controls the keyboard after the signals reach the 8042 Keyboard Controller the USB keyboard is treated just like a conventional keyboard if the BIOS is correctly designed to work with USB keyboards As discussed previously in this chapter a BIOS upgrade might be necessary in some cases to provide proper support of USB keyboards on some systems The system chipset also must sup port USB Legacy features Typematic Functions If a key on the keyboard is held down it becomes typematic which means the keyboard repeatedly sends the keypress code to the motherboard In the AT style keyboards the typematic rate is adjusted by sending the appropriate commands to
80. re for either the EnduraPro 104 http www pckeyboard com ep104 htm1 or the Customizer 101 or 104 http www pckeyboard com customizer htm1 These are brand new not reconditioned or rebuilt keyboards The EnduraPro 104 is notable for including a built in TrackPoint pointing device and a pass through mini DIN mouse port being programmable and reconfigurable requiring no special drivers and of course having the famous buckling spring keyswitches Because of the buckling spring capacitive keyswitches and the resulting clickety feel I ve always been a huge fan of the IBM Lexmark and now Unicomp keyboards In my opinion they are the absolute best keyboards in the world and the only ones I willingly use on desktop systems I especially like the fact that they include the IBM TrackPoint because I use a laptop system as my main machine and therefore use only laptops that include the TrackPoint device mainly IBM Toshiba and some Dell HP others The feel and durability of the buckling spring capacitive keyswitches is outstanding and with the integrated TrackPoint I never have to move my hands off the keyboard resulting in much greater efficiency when working with my systems The Keyboard Interface A keyboard consists of a set of switches mounted in a grid or an array called the key matrix When a switch is pressed a processor in the keyboard identifies which key is pressed by determining which grid location in the matrix shows contin
81. ring keyswitch Because this type of switch does not rely on metal contacts it is nearly immune to corrosion and dirt These switches are also very resistant to the key bounce problems that result in multiple characters appearing from a single strike In addition they are the most durable in the industry rated for 25 million or more keystrokes as opposed to 10 20 million for other designs The tactile feedback is unsurpassed because the switch provides a relatively loud click and a strong over center feel The only drawback to the design is the cost Capacitive switch keyboards are among the most expensive designs The quality of the feel and their durability make them worth the price however Originally the only vendor of capacitive keyswitch keyboards was IBM Although some of IBM s older keyboards still feature capacitive keyswitches most current IBM keyboards use rubber dome or other lower cost keyswitches In 1991 IBM spun off its keyboard printer division as Lexmark which then spun off the keyboard division as Unicomp in 1996 Today Unicomp still manufactures and sells IBM keyboards with the classic buckling spring capacitive switch clickety as some would say technology As a bonus it also has models with the IBM trackpoint built in You can purchase new Unicomp IBM keyboards direct by calling its toll free number 800 777 4886 or by visiting its online store http www pckeyboard com My personal recommendations a
82. s the electrical signals sent from the mouse into positional information and indicates the status of the buttons The standard mouse drivers in Windows are designed for the traditional two button mouse or scroll mouse in Windows Me 2000 XP or later but increasing numbers of mice feature additional buttons toggles or wheels to make them more useful These additional features require special mouse driver software supplied by the manufacturer Pointing Device Interface Types The connector used to attach your mouse to the system depends on the type of interface you are using Three main interfaces are used for mouse connections with a fourth option you also occasion ally might encounter Mice are most commonly connected to your computer through the following three interfaces E Serial interface E Dedicated motherboard PS 2 mouse port E USB port 1042 Chapter 18 Input Devices Serial lt lt A popular method of connecting a mouse to older PCs is through the standard serial interface As with other serial devices the connector on the end of the mouse cable is typically a 9 pin female con nector some very old mice used a 25 pin female connector Only a couple of pins in the DB 9 or DB 25 connector are used for communications between the mouse and the device driver but the mouse connector typically has all 9 or 25 pins present Because most older PCs come with two serial ports a serial mouse can be plugged into either COM1
83. s to fail or become dirty and most importantly does not require you to move your hands from the home row to use it This is an absolute boon for touch typists I was fortunate enough to meet the actual creator and designer of this device in early 1992 at the spring Comdex Windows World in Chicago He was in a small corner of the IBM booth showing off his custom made keyboards with a small silicone rubber nub in the middle In fact the devices he had were hand built prototypes installed in standard desktop keyboards and he was there trying to get pub lic reaction and feedback on his invention I was invited to play with one of the keyboards which was connected to a demonstration system By pressing on the stick with my index finger I could move the mouse pointer on the screen The stick itself did not move so it was not a joystick Instead it had a sili cone rubber cap that was connected to pressure transducers that measured the amount of force my fin ger was applying and the direction of the force and moved the mouse pointer accordingly The harder I pressed the faster the pointer moved After playing around with it for just a few minutes the move ments became automatic almost as though I could just think about where I wanted the pointer to go The gentleman at the booth turned out to be Ted Selker the primary inventor of the device He and Joseph Rutledge created this integrated pointing device at the IBM T J Watson Research Center When
84. sors detect movement of the wheels by watching an internal infrared light blink on and off as the shutter wheel rotates and chops the light These blinks are translated into movement along the axes This type of setup called an opto mechanical mechanism is still the most popular type of mouse mechanism see Figure 18 9 although optical mice are gaining in popularity Figure 18 10 shows a PS 2 mouse connector Pointing Devices Chapter 18 1039 As the mouse is dragged the mouse ball rolls in the same direction as your hand Your computer receives signals via the mouse cable which are translated by your operating system into the distance direction and speed of your movements The mouse buttons send signals to your computer which in turn sends those signals to the software As the ball rolls it turns a pair of internal rollers that touch the ball at 90 degree angles One roller controls vertical movement while the other controls horizontal movement The pair of rollers are connected to an encoder wheel which is turned as the rollers turn Metal contact points along the edge of each encoder make contact with two pairs of contact bars creating an electrical signal The number of signals corresponds to the speed and distance you have moved the mouse horizontally or vertically Figure 18 9 Typical opto mechanical mouse mechanism Figure 18 10 Typical PS 2 type mouse connector Optical Mice The oth
85. st response time possible generally favor the responsiveness of a wired optical mouse over any wireless mouse Although minimal some lag time does exist Some mice can require up to 0 25 centimeter of movement before responding This lag time can also affect users doing graphi cal work requiring the superior consistency and accuracy of a wired optical mouse although the latest dual sensor wireless optical mice have accuracy on par with wired optical mice E Pointer speed Conventional wired optical mice transmit their positions about 120 times per sec ond whereas wireless mice that use a USB receiver transmit their positions about 40 50 times per second If you use a mouse to play fast action games you might find a corded mouse a bet ter choice because of the more frequent position updates it provides Troubleshooting Wireless Input Devices If your wireless input device does not work check the following E Battery failure The transceivers attached to the computer are powered by the computer but the input devices themselves are battery powered Check the battery life suggestions published by the vendor if your unit isn t running as long as it should try using a better brand of battery or turning off the device if possible E Lost synchronization between device and transceiver Both the device and the transceiver must be using the same frequency to communicate Depending on the device you might be able to resynchronize the device and tr
86. t part of your purchasing decision Early laptop systems often used smaller than normal keys to minimize the size of the keyboard which resulted in many complaints from users Today the keytops on portable systems are usually compara ble in size to that of a desktop keyboard although some systems include half sized keytops for the function keys and other less frequently used keyboard elements In addition consumer demand has caused most manufacturers to retain the inverted T design for the cursor keys after a few abortive attempts at changing their arrangement Of course the most obvious difference in a portable system keyboard is the sacrifice of the numeric keypad Most systems now embed the keypad into the standard alphabetical part of the keyboard as shown in Figure 18 2 To switch the keys from their standard values to their keypad values you typi cally must press a key combination involving a proprietary function key often labeled Fn This is an extremely inconvenient solution and many users abandon their use of the keypad entirely on portable systems Unfortunately some activities such as the entry of ASCII codes using the Alt key require the use of the keypad numbers which can be quite frustrating on systems using this arrangement Keyboards Chapter 18 1021 OGUVGUUVLUTOOIVGUUL J CL JUUUCLVUYMEevVUUL I CJoOCVCVCCVC OU AgVHBOL 3 l GGnenvngnin CJ C MCI C
87. the keyboard processor This is impossible for the earlier PC XT keyboard types because the keyboard interface for these types is not bidirectional AT style keyboards have programmable typematic repeat rate and delay parameters You can adjust the typematic repeat rate and delay parameters with settings in your system BIOS although not all BIOS chips can control all functions or in your operating system In Windows you use the Keyboard icon in the Control Panel in DOS you use the MODE command The next section describes how to adjust the keyboard parameters in Windows because this is more convenient than the other methods and enables the user to make further adjustments at any time without restarting the system Adjusting Keyboard Parameters in Windows You can modify the default values for the typematic repeat rate and delay parameters in any version of Windows using the Keyboard icon in the Control Panel The Repeat Delay slider controls the num ber of times a key must be pressed before the character begins to repeat and the Repeat Rate slider controls how fast the character repeats after the delay has elapsed Keyboard Technology Chapter 18 1029 Note The increments on the Repeat Delay and Repeat Rate sliders in Keyboard Properties in the Control Panel correspond to the timings given for the MODE command s RATE and DELAY values Each mark in the Repeat Delay slider adds about 0 25 seconds to the delay and the marks in the Repeat R
88. tion which is included on the disc packaged with this book Driver Software Most mice and other pointing devices in use today emulate a Microsoft mouse enabling you to have basic two button plus scrolling functions with current versions of Windows without loading any spe cial drivers However if your mouse has additional buttons or other special features you will need to install device specific drivers available from the mouse vendor If you plan to use the mouse from a Windows 9x Me command prompt or with DOS you must load the driver manually To learn more about this process see Mouse Driver Software in the Technical Reference section of the disc packaged with this book Scroll Wheels Late in 1996 Microsoft introduced the IntelliMouse which differed from standard Microsoft mice by adding a small gray wheel between the mouse buttons This was the first scrolling mouse and since then Logitech IBM and virtually all other mouse vendors have made scroll wheels or similar devices standard across almost all models including OEM mice bundled with computer systems The wheel has two main functions The primary function is to act as a scrolling device enabling you to scroll through documents or Web pages by manipulating the wheel with your index finger The wheel also functions as a third mouse button when you press it Although three button mice have been available for years from vendors such as Logitech the scrolling function pr
89. to the system conventional mice use a wire and connec tor whereas wireless mice use a radio frequency or infrared transceiver in both the mouse and a separate unit connected to the computer to interface the mouse to the computer The housing which is made of plastic consists of very few moving parts On top of the housing where your fingers normally rest are buttons There might be any number of buttons but in the PC world two is the standard If your mouse has additional buttons or a wheel specialized driver soft ware provided by the mouse vendor is required for them to operate to their full potential Although the latest versions of Windows support scrolling mice other features supported by the vendor still require installing the vendor s own mouse driver software Ball Type Mice The bottom of the mouse housing is where the detection mechanisms or electronics are located On traditional mice the bottom of the housing contains a small rubber ball that rolls as you move the mouse across the tabletop The movements of this rubber ball are translated into electrical signals transmitted to the computer across the cable Internally a ball driven mouse is very simple too The ball usually rests against two rollers one for translating the x axis movement and the other for translating the y axis movement These rollers are typically connected to small disks with shutters that alternately block and allow the passage of light Small optical sen
90. trols E Numeric keypad E Function keys The 101 key arrangement is similar to the Selectric keyboard layout with the exception of the Enter key The Tab Caps Lock Shift and Backspace keys have a larger striking area and are located in the familiar Selectric locations Ctrl and Alt keys are on each side of the spacebar and the typing area and numeric keypad have home row identifiers for touch typing The cursor and screen control keys have been separated from the numeric keypad which is reserved for numeric input As with other PC keyboards you can use the numeric keypad for cursor and screen control when the keyboard is not in Num Lock mode A division sign key and an addi tional Enter key have been added to the numeric keypad The cursor control keys are arranged in the inverted T format that is now expected on all computer keyboards The Insert Delete Home End Page Up and Page Down keys located above the dedicated cursor control keys are separate from the numeric keypad The function keys spaced in groups of four are located across the top of the keyboard The keyboard also has two additional function keys F11 and F12 The Esc key is isolated in the upper left corner of the keyboard In addition dedicated Print Screen Sys Req Scroll Lock and Pause Break keys are provided for commonly used functions Foreign language versions of the Enhanced keyboard include 102 keys and a slightly different layout from the 101 key U S v
91. uity The keyboard processor which also interprets how long the key is pressed can even handle multiple keypresses at the same time A 16 byte hardware buffer in the key board can handle rapid or multiple keypresses passing each one to the system in succession Keyboard Technology Chapter 18 1027 When you press a key the contact bounces slightly in most cases meaning that several rapid on off cycles occur just as the switch makes contact This is called bounce The processor in the keyboard is designed to filter this or debounce the keystroke The keyboard processor must distinguish bounce from a double key strike the keyboard operator intends to make This is fairly easy though because the bouncing is much more rapid than a person could simulate by striking a key quickly several times The keyboard in a PC is actually a computer itself It communicates with the main system in one of two ways E Through a special serial data link if a standard keyboard connector is used E Through the USB port The serial data link used by conventional keyboards transmits and receives data in 11 bit packets of information consisting of 8 data bits plus framing and control bits Although it is indeed a serial link in that the data flows on one wire the keyboard interface is incompatible with the standard RS 232 serial port commonly used to connect modems The processor in the original PC keyboard was an Intel 8048 microcontroller chip Newer
92. ur driver refuses to recognize the mouse at all regardless of its type try using a different mouse that you know works Replacing a defective mouse with a known good one might be the only way to know whether the problem is indeed caused by a bad mouse I have had problems in which a bad mouse caused the system to lock right as the driver loaded or when third party diagnostics were being run on the system If you use a DOS based diagnostic such as Microsoft MSD or AMIDIAG and the system locks up during the mouse test you have found a problem with either the mouse or the mouse port Try replacing the mouse to see whether that helps If it does not you might need to replace the serial port or bus mouse adapter If a motherboard based 1046 Chapter 18 Input Devices mouse port goes bad you can replace the entire motherboard which is usually expensive or you can just disable the motherboard mouse port via jumpers or the system BIOS setup program and install a serial mouse instead This method enables you to continue using the system without having to replace the motherboard On systems with Windows 98 Me 2000 XP you also can switch to a USB mouse using USB ports on your motherboard or by installing a PCI based USB card provided your system has a USB port Note To learn more about using the Microsoft MSD diagnostic program to test for mouse or mouse port problems see Chapters 17 and 25 of Upgrading and Repairing PCs 11th Edi
93. ween the installed keyboard layouts Keyboard Mouse Interface Connectors Keyboards have a cable with one of two primary types of connectors at the system end On most aftermarket keyboards the cable is connected inside the keyboard case on the keyboard end requiring you to open the keyboard case to disconnect or test it different vendors use different connections making cable interchange between brands of keyboards unlikely When IBM manufactured its own enhanced keyboards it used a unique cable assembly that plugged into both the keyboard and the system unit to make cable replacement or interchange easy Current IBM keyboards unfortunately no longer use either the shielded data link SDL connector inside the keyboard or the telephone cable style removable plug in external keyboard connector used on some more recent models Although the method of connecting the keyboard cable to the keyboard can vary all PC keyboards except those using the USB port use either of the following two connectors to attach to the computer E 5 pin DIN connector Used on most PC systems with Baby AT form factor motherboards E 6 pin mini DIN connector Used on PS 2 systems and most PCs with LPX ATX and NLX mother boards Figure 18 8 and Table 18 2 show the physical layout and pinouts of all the respective keyboard con nector plugs and sockets although the 6 pin SDL connector is not used in this form by most key board vendors most non IBM keyboards use a
94. yboards or the old foam element keyboards but they are still no match for mechanical or capacitive keyswitch models in their feel One interesting exception is the line of keyboards made by KeyTronicEMS using its center bearing ver sion of membrane keyswitches Most of its keyboards feature Ergo Technology which has five levels of force from 35 grams to 80 grams depending on the relative strength of the fingers used to type various keys As little as 35 grams of force is required for keys that are used by the little finger such as Q Z and A and greater levels of force are required for keys used by the other fingers The spacebar requires the most force 80 grams This compares to the standard force level of 55 grams for all keys on normal keyboards see Figure 18 6 For more information about keyboards with Ergo Technology visit the KeyTronicEMS Web site www keytronic com To find the best membrane keyboards from the vast numbers on the market look at the lifespan rat ing of the keyswitches Longer lasting keyswitches make the keyboard cost more but will lead to a bet ter experience over the life of the keyboard Keyboard Technology Chapter 18 1025 Keytop Plunger Membrane circuit board Silicone rubber dome Figure 18 5 A typical membrane keyswitch used in NMB keyboards
95. you must look carefully at the detailed specifications for the keyboard to see whether it is a mechanical keyswitch model Foam Element Switches Foam element mechanical switches were a very popular design in some older keyboards Most of the older PC keyboards including models made by Key Tronic and many others used this technology These switches are characterized by a foam element with an electrical contact on the bottom This foam element is mounted on the bottom of a plunger that is attached to the key see Figure 18 4 Press down on keytop Return spring Flexible Oia foam gt Ose Foil layer on bottom of foam Foil layer makes Contacis m connection between circuit boar contacts Figure 18 4 Typical foam element mechanical keyswitch When the switch is pressed a foil conductor on the bottom of the foam element closes a circuit on the printed circuit board below A return spring pushes the key back up when the pressure is released The foam dampens the contact helping to prevent bounce but unfortunately it gives these keyboards a mushy feel The big problem with this type of keyswitch design is that little tactile feedback often exists These types of keyboards send a clicking sound to the system speaker to signify that contact has been made Preferences in keyboard feel are somewhat subjective I personally do not favor the foam element switch design Another problem with this type of design is that it is m
96. your desktop keyboard For desktop systems I use a Lexmark keyboard with the IBM licensed TrackPoint device built in This makes for a more consistent interface between desktop and notebook use because I can use the same pointing device in both environments You also can buy these keyboards directly from Unicomp Unicomp keyboards are TrackPoint III compatible IBM also offers TrackPoint IV in some of its high end keyboards available at retail Mouse and Pointing Stick Alternatives Because of Windows many users spend at least as much time moving pointers around the screen as they do in typing making pointing device choices very important In addition to the mouse and the pointing stick choices discussed earlier in this chapter several other popular pointing devices are available including Track pads such as the Cirque GlidePoint E Trackballs from many vendors E Upright mice such as the 3M Renaissance Mouse All these devices are treated as mice by the operating system but offer radically different options for the user in terms of comfort If you re not satisfied with a regular mouse and don t want to use an integrated pointing stick such as the TrackPoint II III IV look into these options GlidePoint Touch Pad Cirque originated the touch pad also called a track pad pointing device in 1994 Cirque refers to its technology as the GlidePoint and has licensed the technology to other vendors such as Alps Electric which also uses

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