the rev C manual
Contents
1. P4 30 5 and 4 pins Line or dot 4 colored at pin 1 bands end Trimpot Resistor SIP Resistor Toggle Switch Pushbutton R2 4 6 10 Part number right side up Dot or line Socket pin Integrated circuits ICs greatly enlarged Comments on components The resistors use colored rings to identify their resistance The other parts have numbers but you may need a magnifying glass to read them Capacitors have their value in Farads usually picoFarad For example 22 is 22pF 22 picoFarad 101 is 10 with one zero after it i e 100pF 104 is 10 with 4 zeroes after it pF that s 100 000pF 0 1uF microFarad ICs have room for a part number but it s hidden between extra letters i e the 1802 is CDP1802ACE Leave the ICs in their tubes until you re ready to install them They are easily damaged by static electricity You know that teeny little spark you get if you touch something metal after petting the cat or walking across a carpet That s static electricity In the microscopic world inside an IC it hits like a lightning strike Boom Your IC is dead Assembly Assembly is a work in process I ll just describe how I built mine Please let me know if you find better ways to do it Check off the steps as you go X in case you get interrupted and have to come back to it later A couple things to keep in mind To fit both boards in an Altoids tin they must be built with the parts as low as2. about computer design construction and programming in the process A dozen companies began producing versions of the ELF also selling for low prices It was the Legos of computers a simple building block computer that could be assembled many ways to become almost anything limited only by your imagination I learned about computing on my ELF It set me on a career in engineering as it did for thousands of others 1802 s got designed into all sorts of amazing things video games music synthesizers Chrysler engine computers military weapon systems and even NASA missions such as the Galileo spacecraft Eat stardust x86 PCs So return with me now to those thrilling days of yesteryear when the heroic pioneers of the microcomputer revolution learned how to build their own computers from scratch and programmed them to do incredible things all for a tiny amount of money What can you do with an 1802 The Membership Card is much like the Parallax BASIC Stamps you can program it to do simple tasks and serve as the brains of various projects It can blink lights drive relays or small motors run displays make annoying sounds with a speaker read switches or sensors to measure things perform calculations make decisions and more Its machine language is very simple or there are BASIC interpreters and C compilers for the 1802 that can be downloaded free to write and run really ambitious programs Once a program is loaded it can be retai
3. elf 1 33 htm This is the Aug 1976 Popular Electronics article that introduced the ELF to hobbyists Much of it applies directly to the Membership Card http www ittybittycomputers com IttyBitty ShortCor htm A Short Course in Programming by Tom Pittman An excellent introduction to programming the 1802 http datasheets chipdb org RCA MPM 201B_CDP1802_Users_Manual_Nov77 pdf An online copy of RCA s User Manual for the 1802 Must read reference material http www cosmacelf com The COSMAC ELF fan club with lots of information on the many commercial and hobbyist variants http www retrotechnology com memship memship html This is Herb Johnson s website on the Membership board He built one of the first ones and has done a great job of documenting it on his website many thanks Herb I ll be providing updates to the manual software examples etc there 16 Mugshots of the Elf Membership Card 3 board Set PC PARALLEL PORT OOOOOOOO Q RUN WRITE 7 6 5 43 2 1 ODOOOOOOOD IN WAIT CLR READ ELF MEMBERSHIP CARD LOAD leeahart earthlink net Cover Card 1 1 scale Can use as a drilling template COR REW ADDR LATCH COSMAC ELF MEMBERSHIP CARD P MEMORY COSMAC MICROPROCESSOR ponceek RAM OR EPROM leeahart earthlink net ez 00 tx P3 OUT4 m INP 4 E2 BE Membership Card 1 1 scale Part location and placement guide 17 U1 U3 CDP 19 02ACE 74HC373 12 MICROPROCESSOR ADDRESS LATCH ue CLK
4. is also good Lead free electronics solder is also OK though it doesn t solder as well It must be rosin core electronics solder NOT acid core plumbing or sheet metal solder Wire cutters The smaller the better Nothing is big here Needle nosed pliers For bending or straightening lead wires holding nuts etc Screwdriver with a 1 8 wide or smaller blade For tightening mounting screws and adjusting the clock frequency pot A magnifying glass My old eyeballs aren t good enough to read the markings on some of the parts or see whether a solder joint is done right or is shorted to the pad next to it Your eyes may not be that good either You ll need to know how to solder This isn t the right kit for learning how to solder The pads are pretty small and if you make a mistake it can be a real bear to get the part off and put back on the right way First make sure you have all the parts I supplied everything that goes on the printed circuit board but you may need to gather a few other things yourself I ll supply Altoids tins as long as my supply holds out not long but you will have to drill or cut the holes in it for the switches LEDs and connectors The Membership Card is your entry into the COSMAC College of Computer Knowledge We ll start with an aptitude test See if you can find and identify the common electronic components listed on the next page Place a check mark in the box X as you find them If any are missing let m
5. ty CLEAR Reset the 1802 sets RO to address 0000 6 100 READ Set S8 down so we can read memory 7 000 ae oer ee e i LOAD Set both S9 and S10 down X00 0 01111011 a Press the IN button This reads memory address 0000 An ABa displays its contents in the LEDs 0111 1011 which is hex 7B then advances RO from address 0000 to 0001 x000 01111010 b Press IN again Displays 0111 1010 hex 7A from 7 AA address 0001 then advances RO from 0001 to 0002 x000 00110000 c Press IN again Displays 0011 0000 hex 30 from 3 address 0002 then advances RO to 0003 x000 00000000 c Press IN again Displays 0000 0000 hex 00 from W0 0O address 0003 then advances to 0004 If our program is correct now we can run it 8 10 ba ou Ma ou fe oe fo e CLEAR Reset the 1802 set RO back to address 0000 9 1 1 RUN Both S9 and S10 up The 1802 begins running the program starting at address 0000 This program is very simple it tells the 1802 to turn the Q LED on then turn Q off then repeat forever But it s doing it so fast that the LED looks half on To prove it s really going on and off we can use the WAIT mode to temporarily stop the program and then resume again 10 01 ae ee a a ae A WAIT Stop right where you are The 1802 freezes right where it is in the program The Q LED might be caught on or off By flipping S10 up and down we can Run and Wait the program sometimes catching Q on and so
6. The 1802 Membership Card FA dan es Pee SNR et at PIRN For me and you a by Lee Hart 814 8th Ave N Sartell MN 56377 leeahart earthlink net last revised 5 16 2012 Oa nd the 1802 What the heck is this It s an adventure by cracky The Membership Card is your ticket to the weird and wonderful world of microcomputing Our guide will be the COSMAC 1802 perhaps the oddest and most entertaining microprocessor yet invented I hope you will find this manual to be equally odd and entertaining The COSMAC 1802 was created in the 1970 s at the dawn of the microcomputer revolution by Joseph Weisbecker of RCA Corporation It used their new CMOS fabrication process which had very low power consumption high noise immunity and was very simple to use It was intended for military and aerospace applications too tough for other microcomputers to survive But Joe was a hacker at heart He wrote a series of articles starting in the August 1976 issue of Popular Electronics magazine called Build the COSMAC ELF It described a simple low cost computer using the 1802 microprocessor At the time microcomputer systems cost hundreds to thousands of dollars Hmm they still do today But Weisbecker s ELF cost less than 100 Yet it was an honest to goodness real live computer able to do anything its much bigger cousins could do albeit a bit slower and cruder It was the ideal computer trainer Hobbyists built thousands of ELFs learning
7. XTAL b22 43256 32K RAM 25 Ao ry ney A CLOCK FREQ 20 1000 KHZ PPP e AUWN S rll R3 100K 1N4148 MED RS DD 100K cs 5 1Vz L 1N5231B u4c 10 4093 7INP4 7 D10 1N4148 CLEAR fWAIT U2 part pin ts 1 23 26 27 P2 Jumpers P3 Notes 43256 62256 Used C1 7 DO 11 J1 2 R1 13 6264 6116 27256 The two boards stack together I O board on top both component For 1804 75 6 drill feedthru o P1 J1 are 0 025 Pins on 0 1 Set toggle switches 50 10 UP ta Pushbutten 11 shown in unpressed Rev B Add QI to gate U2 CE with x is a 24 pin chip put its pin 1 inte socket pin RER D T ein F ange ae s option ange pP pin l1 VDD 3 to 5 VDC 3 AA cells etc 7 Rev B Error Silkscreen maslabels P4 power pin 2 RUN to pin 1 te run open to stop osc 8 Rev c Change R4 8 10 from 470K t connector pin 3 LED to pin 4 enables LEDs open is off 3 aya kd pin 4 VSS common for power GND etc aA i a a a A ho pants 18 Front Panel Card gt lt Membership Card J1 1 PIN HEADER Pi MOLEX KK SOCKET US 74HC257 DO 3 4 Q4 Q0 Di 18 qa Q7 DZ 4 D3 17 Q6 D4 7 Q2 D5 14 Qs Des oe D7 15 aa 74HC374 OUTPUT LATCH GBASE 1 C Control BASE 2 name bit direction for parallel port SELI gt sS4 mr 10 PE gt sS MWR 11 E ACK gt S6 A ee Tes POT oe
8. ak if your front panel holes don t match the board well enough NOW solder the parts to the board with the front panel holding them all in position Remove the screws from the D connector Remove the PC board from the panel so you can install the rest of the parts The above may seem tedious but it guarantees that the parts will be soldered in the right positions to match the holes in your front panel 10 Pla Plb Plc Mount these connectors on the BOTTOM of the Front Panel board Three 10 pin parts are supplied as I couldn t find a single 30 pin part The two feet point to the center of the board Cut off these feet after the connectors are mounted R11 10 pin SIP resistor network with nine 1K resistors black marked E1K Note the end with the black dot or line this is pin 1 It goes on the LEFT end toward the center of the board and in the hole with the square solder pad Solder each lead and cut off the excess Install R12 and R13 exactly the same as R11 R12 8 pin SIP with seven 100K resistors yellow marked 8X 1 104LF R13 8 pin SIP with seven 100K resistors yellow marked 8X 1 104LF Install the fixed resistors and capacitor as was done on the Membership Card R8 499k 1 yellow white white orange brown R9 499k 1 yellow white white orange brown R10 499k 1 yellow white white orange brown C7 0 1uF yellow marked 104 Install the ICs the same as U3 U7 on t
9. an the chips You can add sockets if you like but it is likely to increase the height ICs are polarity sensitive they must be installed with the pin 1 end matching the marking on the board The pin 1 end may be marked in a number of ways with a dot notch or line etc When the writing on the IC is right side up and facing you pin 1 is at the lower left corner See the illustration on page 6 to find pin 1 For each IC make sure its pins are straight and parallel to each other so it fits into the holes on the board If they are bent slightly straighten them with your needle nosed pliers wm OSS U3 74HC373 or 744HCT373 20 pin IC Install at U3 and bend a couple pins slightly if necessary to hold it in place Be sure pin 1 is at the correct end Then solder all pins and cut off the excess U4 4093 14 pin IC Install the same as for U3 US 4013 14 pin IC U6 74HC244 or 74AHCT244 20 pin IC U7 74HC374 or 74HCT374 20 pin IC We re almost done Now for the pin headers J1 30 pin header The little square pins are held by a black plastic body If you don t plan to put the boards in an Altoids tin just put the header on the board and solder it in place If you DO want it to fit in an Altoids tin the plastic body must be removed Here s how I did it Put the pin header loosely in a small vice with the plastic body sitting on top of the jaws Pound the short end of each
10. as shown on the board Solder each lead and cut off the excess D10 1N4148 Install it the same as D9 D11 1N5231B Install the same as D9 and D10 IC socket pins or sockets You have some choices here Ideally you don t need sockets or socket pins they add cost make the board higher and a little less reliable sockets will be the least reliable part of the whole computer But having them makes troubleshooting and chip replacements easier U1 1802 integrated circuit I supplied socket pins which require some fussy work They have an extremely low profile but are tiny and easy to lose Push a socket pin onto each pin of the 1802 IC Put the 1802 with socket pins on the board and then solder all the pins Do not use too much solder or it will solder the IC to the board If you do it right the 1802 can be unplugged from the board just like an IC in a socket Do not cut the socket pins The bottom needs to remain closed so solder won t get inside If you want to use your own IC socket place it at location U1 with the end with the notch matching the one shown on the board Solder each pin and cut off the excess Install the 1802 in the socket with pin 1 at the correct end U2 memory chip could be a RAM or EPROM from 2k to 32k bytes Install as described for U1 above Now let s do the rest of the ICs I did not supply sockets or socket pins for them They are not likely to fail and the sockets cost more th
11. e know so I can send it out before you get bored and go back to watching TV Ready Turn the page to begin an adventure that could last a lifetime Front Panel Card PON LO OO LOO LO PO 2S LOS LOO LOO LON LON LON LRN LON LO LO LON LR LON LO PO LO LO Sf O OE LOO FO Oe I LON Oa E i Pee Parts List Quantity Identifier Description Source 1 Cl capacitor 22pF NPO ceramic yellow marked 22K Jameco 332541 4 C2 4 7 capacitor 0 luF X7R ceramic yellow marked 104 Jameco 544868 1 C5 supercapacitor 0 047F 5 5vdc green 0 5 dia 1 C6 capacitor 1OOpF ceramic yellow marked 101 Jameco 81525 9 DO 8 LED T1 3 4 red Jameco 697611 2 D910 diode 1N4148 Jameco 36038 I D11 diode 1N5231B 5 1v zener standard Jameco 179047 or 1N4625 5 1v zener optional lower power l Jl 30 pin header 0 025 sq pins on 0 1 centers Jameco 103342 I J2 25 pin connector DB25F female vertical PC mountJameco 15165 3 Pla b c 10 pin top entry socket Molex 22 18 2101 Digikey WM3241 ND P2 5 pin header 0 025 sq pins on 0 1 centers Jameco 2076789 1 P3 4x2 pin header 0 025 sq pins on 0 1 centers Jameco 109516 l P4 4 pin header 0 025 sq pins on 0 1 centers Jameco 117560 l Ql MOSFET N channel 2N7000 3 leads black Jameco 119423 1 R1 lmeg trimpot Bourns 3266W 3 leads blue cube Jameco 696386 1 R2 resistor 5 6k 5 1 4w green blue orange gold Jameco 691041 2 R3 6 resistor 100k 5 1 4w brown black yellow gold Jamec
12. ge with steps in it to drill a dozen or so sizes from 1 8 to 1 2 The D connector opening will have to be cut out with a nibbler or a lot of hand filing Flash I now have a Cover Card with all the holes and silkscreened labels see page 17 Just cut a big ragged hole in the bottom of the Altoid tin lay this card over the hole and solder glue or screw it in place The Cover Card is 10 plus 2 shipping from me Lee Hart contact info is on the cover 11 Pushbutton switch Label on this side D8 LED Place it Snap it onto the board on the board with with the label side UP the shorter lead and Do not solder it yet flat side on the right as shown 10 Toggle switch Place it on the board Bend a lead slightly so it won t fall off Hold it in place with a scrap bit of lead wire poked into the hole in a terminal Yes it s a tight fit Do not solder it yet DO D LEDs Install as for D8 above w J2 Temporarily mount D connector J2 to YOUR FRONT PANEL with the 4 hardware provided The side with the most pins goes toward the top Do not solder it yet 59 50 Place on board as for 510 Do not solder yet Now fit the PC board with the LEDs and switches into the holes in your front panel Work the board down as close as possible to the metal panel This forces all the parts into the correct positions to match your front panel holes Careful The switches can bre
13. h is down X means push the button means the switch state doesn t matter I ll show the switch positions like this Switch numbers and positions on the board S11S10 S9 S8 S7 S6 S5 S4 S3 S2 S1 SO Mode Description 10 oe Gos ce ey ae CLEAR Resets the 1802 PROGRAM 1 BLINK Q FAST Let s load a simple program to blink the Q LED 11S10 S9 S8 S7 S6 S5 S4 S3 S2 S1 S0 Mode Description 2 10 wea Gee er Bucy Ss CLEAR Reset the 1802 sets RO to address 0000 De 101 WRITE Set S8 up so we can write to memory 4 001 LOAD Set both S9 and S10 down x001 01111011 a Set S7 SO to 0111 1011 then press the IN button 7 7 7 A amp B This loads hex 7B Set Q instruction into memory address 0000 displays it in the LEDs then advances RO from address 0000 to 0001 13 X00 1 01111010 b Set S7 SO to 0111 1010 then press IN This loads eh ae a Ga hex 7A Reset Q into 0001 displays it then advances RO to 0002 X00 1 00110000 c Set S7 SO to 0011 0000 then press IN Loads hex 30 3 7 o0 Branch Unconditional into 0002 displays it then advances RO to 0003 x001 00000000 d Set S7 SO to 0000 0000 then press IN Loads hex 00 Oey o0 tells Branch Unconditional where to jump to in this case back to 0 displays it then advances RO to 0004 Our program is loaded Let s read it back to see if it is correct S11S10 S9 S8 S7 S6 S5 S4 S3 S2 S1 SO Mode Description Se o E0 a ee Eng S ee
14. he Membership Card Be sure pin is as shown on the board U8 4071 14 pin IC U9 74HC257 16 pin IC P4 4 pin header Install as described for J1 on the Membership Card Or if you prefer leave off P4 and solder 4 small wires to the board instead with a connector on the other end Check to see that the finished board still fits into the holes in your front panel You may have to re heat and reposition some parts or enlarge some holes in your front panel to make it fit easily The last page of this manual is a cheat sheet summary of operation Cut out one vertical column and fold it to fit inside the Altoids box This keeps it handy for a quick reminder It also keeps the pins on the back of the board from shorting to the metal case Final Assembly Plug the Membership and Front Panel boards together Look between them for any places where parts touch each other and could cause a short Trim any leads that are too long and might touch I don t have enough nuts for all the switches and haven t found a place to buy them so I only supplied 4 sets That s OK they are so close that you can t put nuts on adjacent switches anyway Just use nuts on the end switches in each row Don t bother with washers there is no room for them 11 Next you need to install jumpers on the Membership Card to configure it for the particular size and type of memory chip installed at U2 P2 and P3 Look at the type of
15. ional branch at OOOA makes it start all over again The result is that Q blinks slowly on off about once a second PROGRAM 3 READ SWITCHES AND DISPLAY VALUE IN LEDS Here s a little more complicated program It reads the 8 data switches and displays their settings with the 8 LEDs It tests the Membership Card s ability to read and write the switches and lights Run it with S8 up write address instructions RO Hex Binary mnemonic comments 0000 El 11100001 SEX 1 set X register to 1 0001 90 10010000 GHIO get high byte of register 0 in D sets D 0 0002 B1 1011 0001 PHI 1 put D in high byte of register so R1 00xx 0003 F8 11111000 LDI load D immediately with 0004 10 00010000 10h LO hex 0005 Al _ 10100001 PLO 1 put low half of R1 D so R1 is now 0010 0006 6D _ 01101101 INP 5 input port 5 front panel switches amp write into memory at R1 0007 65 01100101 OUT 5 output to port 5 front panel LEDs the contents of memory at R1 0008 30 00110000 BR branch unconditionally 0009 00 00000000 0 to address 0000 15 Last Writes I m still working on this manual I plan to add more illustrations better assembly directions instructions for hookup and troubleshooting and more programs to get you started Longer term I hope to get a program working that runs on a PC to operate the front panel without all that flippin switch flipping I hope what I have so far is enough to get you going If not please feel free
16. ly leave power connected to P4 pins 1 and 4 Use a DPST double pole single throw switch to break the connections between pins 1 2 and 3 4 This switch provides on and sleep operation On enables the clock and LEDs to work normally Sleep holds memory contents but keeps the power very low a set of AA cells will maintain memory for a year Once you have power connected and nothing smokes proceed to the Operation section following to see if it s working Operation The Front Panel selects the 1802 s operating mode and shows its status The eight Data switches S7 SO set the data to be input S12 is the IN pushbutton pressing it loads the data Data LEDs D7 D0 display the last data loaded or output by the 1802 program LED D8 shows the status of the 1802 s Q register S8 is the READ WRITE switch it controls whether you can read or write to memory S9 and S10 are the mode switches CLEAR and LOAD They select the four operating modes as follows S9 S10 Mode CLEAR LOAD 1802 Operation LOAD down down Waits for the next memory read write next press of the IN button CLEAR down up Reset the 1802 sets registers Q X P and RO all to 0 WAIT up down Stops the program running in memory and waits right where it is RUN up up Runs or resumes running the program in memory Here s an example of how these switches and lights work 1 Power up the card Set switches S11 SO as shown 1 means the switch is up 0 means the switc
17. memory chip installed at U2 Ignore the letters at the beginning and end of the part number and focus on the 4 digit or 5 digit number in the center For example suppose it is marked D43256AC 10L then it s a 43256 a 32k byte RAM Find the table at the bottom left corner of the schematic Look up your chip number to see what jumpers to install For a 43256 for example install jumpers at P2 between pins 1 2 and 4 5 and at P3 between pins 1 3 and 2 4 Power On Now it s time for the smoke test We ll connect power and try not to let any of the magic smoke out Old timers will tell you that electronic devices don t work after smoke comes out The Membership Card takes very little power 3v to 5v DC at less than 1 milliamp plus a milliamp or so for each LED that s lit You can use a few 1 5v batteries an old cellphone charger or even a solar panel from a scrapped calculator for power For example a battery holder with three AA cells in another Altoids tin Or most cellphone chargers have a 5v DC output read the label carefully and if yours is it can be used Zener diode D11 on the Membership Card is an idiot diode If you connect the power supply backwards or if it s over 5 1 volts or is AC instead of DC then D11 will try to short it out and protect the rest of the parts on the board At worst D11 will get hot and fail shorted but it s cheap and easy to replace P4 is the power connector It s a common male header with fo
18. metimes off WAIT mode is handy for debugging because you can check on the state of all the lines with a meter or logic probe to see what is going on 14 Here s a bit longer program It does the same thing blinks Q but does it far slower so it s easy to see it blink on and off Let s simplify the description so it s not so wordy Use the same sequence of switch flipping as for the previous program See if you can figure out how to enter it PROGRAM 2 BLINK Q SLOW Blink the Q LED slowly address machine code RO Hex Binary mnemonic human readable comments 0000 7B 0111 1011 SEQ set Q 0001 FC 11111100 ADI add immediately 0002 01 00000001 1 FAI 0003 3A 0011 1010 BNZ branch if not zero 0004 00 00000000 O to address 0 0005 7A 0111 1010 REQ reset Q 0006 FC 11111100 ADI add immediately 0007 01 0000 0001 1 Teall 0008 3A 0011 1010 BNZ branch if not zero 0009 05 00000101 5 to address 5 000A 30 00110000 BR branch unconditionally 000B 00 00000000 O to address 0 The 1802 is an 8 bit microprocessor 255 is the biggest number it can represent with 8 bits The instructions from 0000 to 0004 are a loop it counts up until it hits 255 Then adding 1 to 255 makes it roll over back to 0 again This satisfies the Branch instruction at 0003 so it stops looping and continues with the instruction at 0005 This turns Q off and loops another 256 times until the counter rolls over again from 255 to 0 The uncondit
19. ned without power for a short time by the onboard supercapacitor or kept forever by maintaining power Remember this is a low power computer it will run for a year on three AA cells The Front Panel can be unplugged and the Membership Card used by itself like a BASIC Stamp The Front Panel isn t needed until you want to change the program or debug or observe operation For stand alone use connect power ground and your desired input and output devices to the 30 pin header directly Jumper J1 pins 13 14 RUN to VDD to turn it on Jumper pins 10 11 WE to MWR to enable writing to memory Specifications What have we got here The Membership Card is a miniature copy of the original PopTronics ELF built using modern parts and repackaged to fit in an Altoids tin It s got the basics of every computer a CPU memory and I O CPU RCA CDP1802ACE microprocessor the brains of the outfit clock RC oscillator adjustable from 20 1000 KHz KiloHertz not Mega or GigaHertz Memory 2k to 32k bytes RAM or EPROM that s kilobytes not megabytes supercapacitor holds data and programs in RAM without power T O one 8 bit output port with LEDs one 8 bit input port with switches one l bit output with LED four 1 bit flag inputs one with a pushbutton switch one interrupt input Connectors 4 pin power connector V RUN LED and V 25 pin DB25 connector with all the I O on it DB25 can plug into a PC parallel port to operate the Membership Card
20. o 691340 4 R4 8 10 resistor 499k 1 1 4w yellow white white orange brown Jameco 691500 1 R5 100k 9 pin SIP 8x100k black body Mouser 652 4609X 1LF 100K 1l R7 resistor Imeg 5 1 4w brown black green gold Jameco 691585 l R11 1k 10 pin SIP 9x1k black body Jameco 97877 2 R12 13 100k 8 pin SIP 7x100k yellow body Jameco 276358 11 SO 10 subminiature toggle switch SPDT Digikey CKN1059 ND 1 S11 subminiature pushbutton switch SPDT Digikey CKN1740 ND 1l U1 1802 microprocessor 40 40 socket pins or low profile IC socket for U1 Mouser 575 393640 1 U2 RAM 6116 2k 6264 8k 62256 32k or 43256 32k or EPROM 2716 27256 or 27C16 27C256 2k 32k 28 28 socket pins or low profile IC socket for U2 Mouser 575 393628 1 U3 74HC373 or 74HCT373 octal latch Jameco 45831 1 U4 4093 quad 2 input NAND Jameco 13400 1 U5 4013 dual D flip flop Jameco 893443 1 U6 74HC244 or 74AHCT244 octal buffer Jameco 45655 1 U7 74HC374 or 74HCT374 octal D flip flop Jameco 45858 1 U8 4071 quad 2 input OR Jameco 13274 1 U9 74HC257 quad data selector Jameco 45719 1 PCB Membership Card and Front Panel circuit boards 2 attached boards 1 Altoids tin candy box 1 bag of 4 hardware to mount J2 2 jackscrews 2 nuts 6 washers 4 jumpers for P2 and P3 headers Did you find them all Here are some hints N Flat 1 f side Shorter lead Capacitor LED co Capacitor P3 C1 4 6 7 8 pins P1a b c d1 P2
21. o hold it in place then solder the leads and cut off the excess Now for the resistors Find R1 it s a 1 megohm trimpot a little blue cube with 3 leads marked W105 Put it at location R1 bend the leads to hold it solder them and cut off the excess Find R2 a 5 6k ohm 5 resistor color bands are green blue orange gold Bend the leads close to the body Insert the leads into the holes on the board at the location marked R2 Bend the leads outward slightly to hold it solder each lead and cut off the excess Repeat this proceedure for the rest of the resistors FE Oe POO es wm R3 100k 5 brown black yellow gold R4 499k 1 yellow white white orange brown R6 100k 5 brown black yellow gold R7 1 meg 5 brown black green gold R5 This is a 9 pin SIP Single Inline Plastic package with eight 100k resistors in it black body marked L91S104 Note the end with the white line this is pin 1 Place it on the board at location R5 with the pin 1 end next to C4 Bend two of the leads slightly to hold it in place then solder each lead and cut off the excess Diodes They are polarity sensitive and have a black band at one end Be sure the banded end matches the band shown on the board D9 1N4148 a reddish glass tube with a wire at each end and 1N4148 printed on it in tiny letters Bend the leads and place it on the board at D9 with the banded end
22. pin into the plastic so all of the pin sticks out the other side Insert the pin header from the BACK side of the board with the plastic body about 1 8 away from the bottom of the board so the pins stick up about 1 4 above the top of the board Solder each pin from the TOP side of the board Cut each pin on the BACK side of the board This also removes the black plastic body P2 5 pin header Mount P2 the same as above The pins must not stick up more than 1 4 above the board P3 6 pin header I supplied an 8 pin part Remove two of the pins so it will fit on the board Then mount the same as J1 and P2 The pins must not stick up more than 1 4 or they will short to the Front Panel board Q1 MOSFET transistor 2N7000 This is also a static sensitive part so beware of static electricity Position the flat side of the body to match the outline on the board Put each lead in its respective hole Solder Q1 and cut off the excess lead length Front Panel assembly Use the bare front panel board as a template to drill your front panel an Altoids tin or your own plastic or metal one I use the bottom of the Altoids tin as my front panel Drill small 1 32 guide holes for the switches LEDs D connector mounting holes and 4 pin power connector P4 Then remove the PC board and drill the holes to their final sizes Use a step drill bit which won t tear the very thin metal this is a long drill bit with a single cutting ed
23. possible Standard IC sockets are too high so I ve supplied special low profile socket pins Likewise the plastic bodies of the 0 025 square pin headers J1 P2 4 are too tall so they have to be removed after soldering You ll also need to trim the leads on the back sides of the boards very short as you go Ready Let s get started Membership Card assembly All parts go on the side of the board with the white silkscreened lettering the top or component side All soldering is done on the other side the back or solder side The only exception is for Pla b and c I ll remind you when we get to it Find Cl a 22 pF ceramic capacitor yellow body labelled 22 or 22K Straighten the leads if necessary with your needle nosed pliers Insert the leads into the holes on the board in the box at the location marked C1 Bend the leads outward slightly to hold it on the board Turn the board over and solder each lead Cut off the excess lead length Now repeat this proceedure for the rest of the capacitors C2 0 1uF yellow marked 104 C3 0 1uF yellow marked 104 C4 0 1uF yellow marked 104 oo ea C6 100pF yellow marked 101 Note This one is smaller and different from C2 C4 Don t get them mixed up C5 0 047F green marked 0 047F Two black stripes mark the negative side The pin next to the black stripes must go in the hole in the board by the sign Bend the leads slightly t
24. s H lt D5 VDD D6 3 a4 O7 16 p3 fos pe pe 16 1A2 Soak ee A oe oees Bad 2a3 HE Pe a ae PERE 1a3 2131 poe ce pet 2a2 13 20 p73 an eile ta4a 8 21 Re ES SD3 DO 9 2A1 11 22 Py po A eae 1 208P me AUTO lt C1 19 A 10 STR lt CO q J2 pS Ta DB25F 74HC244 PC PARALLEL Deeps SEES a i Eri sS EO ENV nme EFA 27 E 100K ye ENVE 2 1 SEELE 28 DE A oe a Va WAIT 29 T3 S0 11 U1T 9 r CPU on bottom nent side up O to open VCC centers 30 to use J2 essed position with TPB and A1S Change VDD C6 82pF Route RUN to P4 I O port from 5 to 4 abels INP4 and OUT4 as 5 7 fixed on Rev C 70K to 499K Change C6 to 100pF arallel port and switches Change RZ to 5 6K TMSI c o Lee Hart 814 Sth Ave N Sartell MN 56377 leeahart Gearthlink net Title Decument Number REV a choxcamaueersoa oevs scu e Date May 16 2012 Sheet 1 of 1 19 The Inside Story Cycle How the 1802 in an Elf computer REALLY works
25. to contact me with comments corrections questions or ways to improve this project My contact information is on the first page Silkscreen errors I will fix these on later versions The names for P1 and J1 on the schematic and silkscreen are reversed Changes along the way July 2010 Changed R8 R10 from 100k to 470k Aug 2010 Rev B board Added Q1 and C6 Changed I O port from 5 7 to 4 5 6 7 Moved RUN to P4 Nov 2010 Changed R4 and R8 10 from 470k to 499k and C6 from 82pf to 100pf for expediency I ran out of 470k and 82pf parts and have lots of 499k and 100pf Jul 2011 Rev C board Fixed silkscreen I O port names was IN5 7 now INP4 was OUTS OUT7 now OUT4 The hardware didn t change the onboard IN and OUT ports still responds to any port number 4 7 Moved a few parts slightly to provide bigger spacings to prevent solder shorts Made a Cover Card a predrilled and labelled board to mount on top of an Altoids box for a finished appearance Aug 2011 Corrected P2 jumper chart on schematic For 6116 2716 2732 P2 was 2 3 changed 3 4 For 2764 P2 was 3 4 changed to 2 3 For 27128 and 27256 P2 was 1 2 and 3 4 changed to 2 3 and 4 5 Sept 2011 Added power supply info Jan 2012 Added photos of finished boards Mar 2012 Added cheat sheet summary page Apr 2012 R1 changed from 500k to Imeg ran out of the 500k pots Links for more data on the 1802 and ELF computers http incolor inebraska com bill_r elf html
26. ur 0 025 square pins on 0 100 centers located in the top left corner of the Front Panel board There are many mating connectors For example the 4 pin cable used in PCs between the CDROM drive and sound card can be used Other choices include Molex KK series 22 01 3047 housing 08 55 0102 terminals www jameco com 234819 234931 Common and easy to use but not latched or keyed AMP latch series 25403S 04 header 25403H 04 R housing 25403T terminals www jameco com 152734 152741 181673 Higher quality latched and keyed if you use its header but hard to install terminals Pin Name Function VDD the power supply positive 3 to 5 volts DC RUN Controls the 1802 s clock oscillator Connect to pin 1 to Run leave pin 2 open to Stop LED LED negative Connect to pin 4 to enable the LEDs leave pin 3 open to disable the LEDs VSS the power supply negative ground common BRWN FR Pin functions are shown above Your power connector should connect your power supply s positive to pins 1 and 2 and the negative to pins 3 and 4 To turn the Membership Card on plug this connector onto the board to make RUN high clock runs and LED low LEDs enabled Unplug the connector to turn it off RUN goes low to stop the clock and the LEDs are disconnected minimizing power When unplugged supercapacitor C4 will hold the program and data in RAM for many minutes 12 If you want to maintain the program and data in RAM indefinite
27. with the PC Size 3 1 2 x 2 1 8 x 3 4 89 x 54 x 19 mm Power voltage 3v to 5v DC current 0 1 to Ima depending on clock speed and supply voltage plus 1 3ma for each LED that is on Aroma a hint of curiously strong peppermint Unlike modern microcomputers that require an expensive PC and huge software programs to do anything the Membership Card is totally self sufficient No PC is needed and no special software is required You can power it from a few AA cells or a scrapped calculator solar panel and program it with nothing but the front panel switches and lights If you ever get stranded on a desert island and need to compute this is the computer to have in your pocket The complete package Membership Card Front Panel and Cover Card all in an Altoids tin Assembly Getting it all together This ain t no Heathkit but I m working to make it as easy to build as possible I want it to be something you can give to your kids and have them experience the thrill of saying I did it It s alive Bwoo hah hah hah To assemble it you ll need the following tools A clean well lit place to work Preferably one without cats or small children Or if the kids are old enough let them help Cats are never old enough to help Soldering iron with a small tip Don t use a soldering gun unless you re desperate soldering these tiny parts and pads with a big fat tip will be a real challenge Solder 63 37 tin lead is best but 60 40
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