Build a microcomputer computer from scratch

Discussion in 'Apple, Inc and Tech Industry' started by prodan1234, Oct 25, 2011.

  1. prodan1234 macrumors newbie

    Sep 5, 2011
    I have been having this dream of mine to create a functional computer. I want it to be one of those 'old' ones that have circuit board and 8-bit processors, similar to the Apple I and Commodore 64. I do not know if that is possible but I want to start everything from scratch (been reading the Jobs biography for a while and I really want to experience the personal computer revolution myself). I want to write my own software (again, I don't know what's possible) and all. I'm pretty much a noobie, so any suggestions and clarifications would be appreciated. Thanks! :)
  2. snberk103 macrumors 603

    Oct 22, 2007
    An Island in the Salish Sea
    First, you find some really pure sand and really really hot furnace. Locating a seam of copper ore would also be high on the priority list....

    ..... :D

    Seriously... a noble endeavour. I think they still sell kits that come with some simple diodes and transisters, and you just need to figure out how to hook them up in the correct sequence. If really want to get back to basics, start with lightbulbs and switches and wires. My late father was involved very early on in the computer era (big iron type stuff), and one of his graduate students tried to teach me the "basics". On/Off; 1/0; etc. The fact that I was 8 at the time might have something to do with why I didn't to ahead and invent the PC the next year.

    Good Luck.
  3. prodan1234 thread starter macrumors newbie

    Sep 5, 2011
  4. Flynnstone macrumors 65816


    Feb 25, 2003
    Cold beer land
    1st you have to decide how far back you want to go. As the other poster alluded to. Could go to tubes ;^)

    You need to decide what you want to do. Perhaps just tinker with nostalgia ...

    or perhaps tinker and build something cool.
    Do you want to make or buy the hardware?
    Do you want to program in assembler? or something higher as C?
    Perhaps buying an old C64 or Apple II and writing some software ...
    Lots O questions.
  5. firestarter macrumors 603


    Dec 31, 2002
    Green and pleasant land
    I've built computer stuff before - designed my own memory and expansion boards, designed the PCBs, etched them myself, soldered them myself, written the code in assembler - back when I was a teenager. I then studied Electronics and worked doing microprocessor design (as part of my Masters thesis).

    There's a lot to learn. Can I ask how old you are, OP, and whether you've experimented with electronics before?

    Going back to the Apple days and building stuff with an early microprocessor like a 6502 coupled to TTL logic will take you a lot of time.

    My recommendation for you is to start off with a newer microprocessor, with a modern development system - in order to start building up electronic and coding skills. Then once you know what you're doing, take another look at building something old-school from scratch.

    Buy an Arduino board. This is a genuine microprocessor development board, that hooks up to your computer using USB. You write apps using a C-like programming language, and you can easily upload these onto the board for testing. The board has a load of electronic connections, to build up additional circuitry.

    Arduino is fun. Even if you don't progress to anything more involved, learning Arduino will enable you to create a large range of useful gadgets!
  6. FredTheDeadHead macrumors member

    Jul 2, 2011
  7. prodan1234 thread starter macrumors newbie

    Sep 5, 2011
    The hardware itself, like RAM and the actual board would be harder to make, so I will buy them. From that point on, I would like to create everything myself and write the software. I didn't thing it would be that hard (Woz was 21 and had almost no college education when he created the Apple I).
    I am 21 and I have experimented with electronics very little (soldering stuff in my grandfather's garage etc.). I am very eager to learn, but there doesn't seem to be one coherent place where I could find all the information, categorized and easy-to-understand. Maybe Khan Academy?
  8. firestarter, Oct 26, 2011
    Last edited: Oct 26, 2011

    firestarter macrumors 603


    Dec 31, 2002
    Green and pleasant land
    You have to ask yourself what you're planning to get out of this. If you want to be like Jobs/Woz and create a new design then that's certainly possible. If you want to build an existing design, then you'd certainly learn a lot of soldering skills - but you'll learn more of the 'how' than the 'why'.

    The best electronic and software designers are self educated! Woz didn't create the Apple I because he was uneducated and it was easy, Woz created it because he was a self-made electronics genius who had spent tens of thousands of hours all through his teens reading data sheets and building other designs. He had the drive to learn this stuff.

    If you're really good at electronics, a lot of this stuff becomes subconscious - you can just see circuits working by glancing at a diagram. Woz would have been on this level and above... these days no-one would design a 45-IC game in their head, without using some pretty sophisticated design and emulation software. Woz could do this in his head.

    Most people can never 'see' electronics in this subconscious way, and formal education makes little difference to that skill.

    I'm sorry if this sounds negative, but I don't think you're going to do this. If you haven't had the interest and drive to suck-down this knowledge in your teens, then I'm doubtful that you'll have the motivation to really master it now. The information is all out there - there have never been so many books, online resources, online data sheet libraries etc. You have hundreds of times more information at your fingertips than Woz had - you just have to hit google.

    Here's a datasheet for a 6502 varient as a start. Woz wouldn't have had much more to go on when building the Apple I - but this would have been enough for him.

    Seriously, look into Arduino - it'll give you an easy entry point - with a great deal of great documentation available in books, on the web and even example podcast videos. You'll need to learn a LOT to get going with Arduino - and that'll be 10% of what you need to know to design, build and program a custom 6502 board. It's an ideal first step.

    One of the best things about Arduino is that the microprocessor has it's own memory (RAM and flash), so that cuts down on circuit complexity a LOT of you want to design your own board. You can take the processor chip off an Arduino board and get it working on your own board with only a handful of extra components.
  9. prodan1234 thread starter macrumors newbie

    Sep 5, 2011
    That was helpful, firestarter , thanks : )
    I was just thinking that I could look at some diagrams, read few articles and have myself an Apple I and then learn the 'way' and ultimately see the same mistakes Woz saw when he was building the Apple II.
    Thank you for your time!
  10. talmy macrumors 601


    Oct 26, 2009
    To start from scratch you would need to design the computer architecture, right down to the instruction set. You would have to choose a technology and do the hardware design. You would probably also want to at least write an assembler for it.

    I'd suggest doing the implementation in an FPGA. I teach a course where groups of 5-6 students each implement a PDP-8 (so they only have to do hardware design and not come up with a new architecture) and run a prime number sieve program (which they have to write) that prints the results to a terminal. It's done in an FPGA using a Nexus-II board, available,400,789&Prod=NEXYS2.
  11. Mord macrumors G4


    Aug 24, 2003
    Depends what you mean by "from scratch".

    I've built a little z80 system and run programs on it, interfaced peripherals to it and the like.

    If you want to do something a little more interesting than that perhaps learn VHDL and design a microporcessor then implement it with an FPGA?
  12. notjustjay macrumors 603


    Sep 19, 2003
    Canada, eh?
    When I was 14 (that would have been 1992) I started sketching a schematic for a simple Z80-based microcomputer. I never got as far as building it (or even finishing the schematic) but I had hopes of one day actually building it. The basic idea would have been to use an EPROM to write simple code and the outputs would probably have been LEDs or something equally simple. It wouldn't have done a whole lot but I was fascinated with the idea of being able to build a functional "programmable" computer.

    A few years later I did manage to build a functional digital clock using a bunch of discrete TTL ICs: counters, NAND gates, 7447 decoders, and 7-segment LED displays, all being driven by an (approximate) 1 Hz pulse train generated from a 555 timer. The thing sucked juice like you wouldn't believe -- I think it got about 40 minutes of runtime from a set of 4 AA batteries. Again, for no practical purpose other than to test the concepts from theory to execution.

    The clock project was much simpler to get off the ground (and easier to get preliminary results) than a Z80 computer, so you might also want to "start small" if your goal is to learn more about circuits. Nowadays it would probably be much more practical to program a microcontroller (PIC, Arduino, or any number of others) but assembling it gate-by-gate was certainly a learning experience!
  13. prodan1234 thread starter macrumors newbie

    Sep 5, 2011
  14. maflynn Moderator


    Staff Member

    May 3, 2009
    Oh my word :eek:

    I already emailed the dude to see if those kits are still available. I'd love to build an altair even if its a replica. That is so freaking awesome
  15. roadbloc macrumors G3


    Aug 24, 2009
  16. gyorpb macrumors member

    Sep 15, 2011
    Build Your Own Z80 Computer by Steve Garcia. Lots of info and tutorials on the basic electronics and concepts behind the microcomputer. Great book.

    The N8VEM single-board computer. Started as a small hobby project, turned into a huge endeavour with contributions from all over the world into a complete system capable of running an enormous software catalogue (CP/M).

    If anything, you'll find lots of links to other projects from these two. You have a lot to learn and a long way to go, but it's mostly fun, so don't worry. Just start simple, and work your way up to the more complex things.

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