Lee Hart’s “Memebership Card”


In an act of retro revival, [Lee Hart] has created this “Membership Card“, an altoid tin sized tribute to the 1802 CMOS chip. Made popular in the late 70s in the RCA COSMAC ELF computer, the 1802 stole many a hackers heart. There’s tons of information available if you explore the site, from history to kit building experiences.

[via Retro Thing)

38 thoughts on “Lee Hart’s “Memebership Card”

  1. I surmise that the purpose is not more than described. It’s a ‘Training’ system designed
    to lead you into 8 bit microproccessing internals.

    The question I’d have, is whether this is a useful endeavour atall.

    I don’t see much application for such a dinosaur design. or a ‘legacy’ processor. there is a reason why nobody tries to revive 1802, Z80s, 650xs, 6800s, or any 68xxx, or any of the 808x families.

    Though I have a life long love of Forth,
    (I still think in RPN)

    These are skills of no real use beyond feeding a personal fascination.

    Those with a need or interest in microcontrollers
    have dozens of better choices.

    I have the utmost respect for those who see a challenge like emulating an LSI11 on an FPGA.
    Or chasing the bounds of discrete logic.

    But, for my part, having lived it, I’d wish these 2nd gen processors would just die like the buggy whip.

  2. Geez, Pogyhauler! I doubt this project is intended for people getting their start with microprocessors. Like you said, there are lots of more modern and better devices.

    I think the purpose of this project is to make people like you and I who remember systems like this happy. I bet I have most of the required chips laying around unused in storage, and it’d be a hoot to complete a little project like this to make a little demonstration system to put in my display case with lots of other interesting (to me, anyhow) technology.

    (BTW, I share your fondness for RPN. I’m going to be lost when my Hewlett-Packard RPN calculators quit working.)

  3. > nobody tries to revive 1802, Z80s, 650xs, 6800s, or any 68xxx

    Oh, but they do! You can find any number of re-builds, emulations, and simulations out there. Not to mention that the z80 architecture lives on at Zilog (so to speak, anyway), and 68k lives on as Coldfire. And look at the state of PIC and 8051 microcontrollers, which are of the same vintage.

    Hmm. What’s the simplest computer with an actual (DMA, cpu-halting) front panel, anyway?

  4. When I first saw RPN, it was as if someone knew how I thought. The Cosmac 1802 brings back memories of Mr. Dipippo’s class in highschool and seeing that not every PC had a keyboard like my Commodore 64 at the time.

  5. To answer the query of person who doesn’t understand what it does — it’s a computer. It can do anything you program it to do. What you might not understand is the input and output. You enter an 8-bit value (which can be instructions or data) through flipping the switches and you see the output on the LEDs. This interface was common in 1970s micros such as the Altair (and the Elf, which this is a clone of, although the Elf actually had a hex readout)

    As for this not being practical, so what? Pretty much *all* electronic hacking is non-practical these days. Hardware hacking hasn’t been mainstream since the days of Heathkit. It’s easier and cheaper (but more boring) to just buy pre-made consumer electronics assembled by depressed suicidal workers in China. Hacking is really just about nostalgia, so why not try to make it as nostalgic as possible?

  6. The 1802 was the heart of the Synclavier sampler from 1977. (The 30 somethings and re-run junkies might remember Stevie Wonder on the Cosby show with it). It was a sampler and did FM synthesis. The light up console buttons were from B52 bombers and I lust for them. In fact software is still being developed for terminal emulators to control these beasts. The parts were all high quality and the analog pre-processing is still sought after.

    The Synclavier computer system was then adapted into the Galileo space probe controlling it’s navigation and digital camera and digital radio systems.

    Both of which were mind bending pieces of technology in the day and far outlasted any reasonable expectations for capabilities because the designers using them were clever.

    Now nearly any consumer gadget now far exceeds them in any measurable spec, but do you think any of them will be around and studied the same way this programing trainer is? There are basic principles to be learned from this kit in a fun and hands on way that glancing over a diagram in a programing class will never teach you.

    I would like to get one to play with some day, but will probably drop an arduino in the next hobby project just because that is easy and available in the same way I am not going to buy a lathe for home improvement projects, but would still like to know how one works.

    Hacking can both be about finding the right sized answer and being clever with knowledge and materials. It is about the process and journey for the maker as much as the final piece.

  7. In the early 80’s I was given a COSMAC Super Elf by the guy who had assembled it in 1975 (he had lost interest in it when he got a — wait for it — Xenix system).

    Today it is hanging on the wall behind my computer, framed. I had it framed in such a way that power can be applied via a discreetly located jack and it still works.

  8. So, I’m the goofball who built this gem for Lee. There is a great article on Wikipedia on retrocomputing for skeptics who want to understand it. For me, it’s strictly a hobby. For my daughter (9 years), it has been a fascinating learning tool. She is picking up basic hardware concepts faster than I would have ever thought playing with it. What can you do with it? You can use it as the brains for your project just as easily as you could use an Arduino and, with this one, you don’t need a desktop super computer acting as a dumb terminal to program the sucker–just flip it in. As for the 1802, it is still in production and in fact the brain of some of the satellites currently in orbit and serving you every day.

  9. if you think about this … the gear from the past is still quite relevant. for someone starting in the micros, yeah there are better choices but if you forget this one term “if we don’t remember out past history we are doomed to repeat it.” keeping things around like the 808X and so on processors is a fairly good idea. one day we may have to revert back to this “old tech” if something catastrophic happens

  10. Small devices are not worthless, just because we can now make 45nm chip running Java, consuming watts of power, in BGA packages and requiring multiple supply rails.

    8-bit CPU’s like the z80 and 6502 are still the work horse of the toy industry, economy consumer products, embedded control and ultra low power devices. In my opinion they’re more useful now than when they were state of the art and cost a lot.

    IMHO: People should be less negative and make some fun projects.

  11. @Justin
    You’re close, but you just missed the gold.
    Synclaviers are a completely different beastie, then what the Gallileo space probe, and his relations are using. Synclaviers are related to the player-pianos. I know that, because my school had one in its music room, could also record rolls, but no one knew that because they never examined the unit. It was also horribly out of tune and sounded worse then a bar piano….

    I should also add that the synclaviers were second generation synthesizers in the Moog style.

    The probes wore specially built systems around the CDP1802 because the device is CMOS based and can resist the unhealthy environemnt that space is for electronics better. It also happens that the technology is still popular for space based activity because of this resistance. Some Rad-Hard electronics are available for the people who still prefer x86 based hardware but it is expensive.

    The CDP1802 has something else going for it, it is more difficult to program then the X86 or the R6502, or even the Z80. Which also made them popular for the space based fraternity.

    I don’t know about the blinking lights that kept the musician company, unless you’ve got facts that insist they were from retired Buffs.

    1. RCA had versions of the CDP18XX family called SOS, Silicon on Sapphire, that was resistant to the intense radiation environment of Jupiter and deep space. Because it was CMOS, the same technology as the CD4000 series logic chips, the power consumption was much lower, also a benefit in space or in remote locations. The TTL, NMOS, PMOS, ECL logic of the that era just consumed to much power.

  12. If I remember correctly the 1802 chip was used in space probes and satellites because the chip’s design was relatively immune to radiation compared to the other chips around at the time. So that means when the radioactive space zombies invade on Dec. 21, 2012 this guy will still have computing power.

  13. Not sure what this is a membership card for. Those part of a community that enjoys exploring and using old tech perhaps? As a membership for any formal or informal, it’s really nothing different that the convention badges that use electronic circuits. All about the participants enjoying themselves, not what those who can’t understand think.

  14. Like GCL said it has a weird architecture unlike any other chip I’ve seen. You have 16 general purpose registers any of which can be used as the program counter or as an index register. No call and return instructions. The COSMAC VIP was my first computer and I still have mine in my shop.

  15. @Todd Decker
    You built a pocket elf!
    Is the parallel port bidirectional?
    Just wondering if you could use it to interface a UART for a serial terminal.
    I vote it as a very wicked hack.

  16. I’m the idiot that designed this thing. :-) Why? Many of the comments above provide clues!

    To really learn something, you need to begin with the basics. Start at the bottom of the ladder, and work your way up. Master each step, them move up to the next.

    But today’s computers have basically sawed off all the bottom rungs of the ladder. Those that learned “way back when” understand how computers really work, and they can build and improve them further. But those starting off today look at computers as an appliance (or worse, as “magic”). They don’t really have a clue how it works. They depend on someone else to design it, build it, and program it for them.

    This leads to hideously inefficient systems. They think that millions of transistors and megabytes of code are needed to do even simple tasks.

    But the vast majority of microcomputer applications are tiny little gadgets, like a pocket calculator for example. If Windows and a Pentium were required to make one, there would *be* no pocket calculators! There would be no way to “climb the ladder” to invent them, perfect them, and make them affordable.

    The idea of the Membership Card is to show how small and simple a computer can really be. You really *can* build it yourself, from scratch. No surface mount, no custom parts, no proprietary code.

    And, you don’t need any expensive programming hardware or megabyte compilers. Yes, there are 1802 C compilers; but there are also Tiny BASICs and FORTHs that run with 1/1000th of the resources.

    1802 machine language seems odd in light of today’s super-complex CPUs; but it is refreshingly simple. It is Turing-complete; it can do anything that any other computer can do. Basically, it has 16 16-bit registers that can be used for anything; program counters, stack pointers, DMA registers, general purpose storage, etc.

    No stack pointer? Hah! You can have *ten* stack pointers if you like. No CALL instruction? Baloney; you write what amounts to microcode to create one. If you want CALL to push the PC and also save three other registers on the stack, then you can! The 1802 makes you *think* about what you want your instructions to do.

    Hardware wise, the Membership Card has the same sort of bit/byte input and output ports as a BASIC Stamp, Arduino, or any other micro. I’m using mine to make small robots; the stepper motors connect directly to the output port, and the input sensors connect directly to the inputs. I’m using the Q output and EF4 input for a serial port to a PC.

    Another feature of this older technology is low power consumption. The Membership card *runs* on 3v at 1ma. There’s a jumper to disable the LEDs, since one LED takes 10 times more power than the whole computer. Or, you can unplug the front panel once you’ve loaded your program (it’s no longer needed) and use the Membership Card by itself.

    It takes no great genius to bury a problem with brute force. In constast, hacking is all about finding clever ways to do more with less. “Running light without overbyte” as Dr. Dobbs used to sas. The 1802 and Elf computers amply demonstrate this principle!

  17. @Lambdadork Slight semantics, you’re right that it doesn’t have stack instructions built into it, but you certainly can implement one, two, or a dozen stacks if you want. A stack is just a basic data structure that can be implemented memory. One doesn’t have to have dedicated instructions built at the processor level to use one.

  18. GCL,
    Synclavier, from New England Digital. It’s a digital FM/additive and sampling workstation from the late 70’s. I have been poking around reading about it’s specs and the block diagrams all after noon and it’s been a great read.


    It’s frequently referenced that the ABLE microcomputer is on the probe, but the only specific reference I read was that it was a digital camera controller. The ABLE system was classified for a long time and shows up in weird places as it was one of the few available powerful microcomputers at the time where big iron was the way for business and academics. There are references that it was used for the appletalk routers.

    I can’t find any specific mentions of the 1802 chip, but as an undocumented TTL system it might have it and only a teardown will show.

    SynclavierII photos have beautiful buttons for the console.

    The synth it’s self were not in the moog style as moogs were analog synthesis and this was all digital. There were many input devices (light pen, terminal and a scripting language called SCRIPT) and the block diagram shows register for storage and transition devices modems and possibly paper tape but certainly is not a player piano (digital synth, no strings attached!)

    There is one reference that a z80 is used for some of the sampling functions.

    And now I think I caught contact Aspergers defending my original post.

  19. @Justin Really nice article on the NED Synclavier. One of the reasons I got back into the 1802 Elf (I built one of the original ones as a kid too in Junior High) was so I could recraft the VIP 4-Channel Super Sound card and play with it’s version of 8-bit synthesis.

    Here is some information about some of the sounds from the First Philadelphia Computer Music Festival where some of the Super Sound music was demonstrated:


  20. I really don’t understand why so many people are unhappy about this, and retro-computing in general. As a 19 year old CS major I find projects like this insanely interesting. I actually spend most of my summer researching trying to design a front panel operated Z80 system. And they are a really good way to learn with. No offense to my professors, but I honestly believe I learned more constructing my N8VEM than i did in my first year of CS courses. Not by fault of theirs but, but building a machine like this just offers so much more to learn.

    Some people may say devices like the Z80 and the 1802 need to die out, but for educations sake I hope not. There is so much to be learned before moving up to an Arduino or Basic Stamp. Not that i have a problem with these devices, but I wouldn’t want to start with one.

  21. 1802’s show up in the darndest places. All sorts of small portable gadgets used them, because nothing at the time could match their low power and noise immunity. Chrysler used them in their ICE emission control computers, for example.

    I just got my rev.C on the Membership Cards, and have them in stock. Bare boards are $25, which includes both the micro card and its front panel card. A complete kit is $89. Prices include the manual and shipping in the USA. Let me know if you’re interested. leeahart at earthlink dot net.

  22. This is an old thread, but still worth a comment or two. Most people here like to play with electronics and the 1802 is a great processor to play with. I believe there should be a better description and write up on this project. Calling this processor a dinosaur is a very immature point of view. That’s like walking past a Ford Model T and saying that car won’t go very fast. This old processor has it’s own unique style. One of the nicer things about this processor is the multiple clocks required to complete each instruction. You can think of it as “seeing the moving parts”. I may be a little biased, since my first computer was a COSMAC ELF, but if someone shows me an old mechanical calculator, I would not be so quick to dismiss it as an inferior product. Certainly an old Curta wouldn’t be used any more in a classroom, but I would certainly value such a treasure. The 1802 is nothing less than a treasure. I bet if you could measure project building and working fun, Lee’s Membership Card project would rank in the top 10% of all kits.

    Josh Bensadon

    PS. I have found the best use of new technology is to preserve and illustrate the old technology. The best movies released on Blu-ray are the old classics.

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