Easy to build Z80 single board computer

[Alexis] sent in a single board computer he’s been working on. The project goal of his build was making it easily reproducible. From looking at the schematics, it’s one of the simplest fully-functional computers we’ve seen. The build runs CP/M 2.2 off of two 3.5 inch floppies. This opens up a lot of options as to what software is already available. Although it operates over a serial terminal, [Alexis] pretty much duplicated an Osborne I, only at double the speed.

[Alexis] got a little e-fame from his earlier 8088 homebrew computer built from very early 8088’s rescued from an electronics junk shop. These 8088 computers made the blog rounds by playing Still Alive with a SID chip from a Commodore 64 and a YM2151 FM synth chip.

For now, I guess we’ll have to settle for a video of [Alexis]‘ Z80 computer running CP/M. Check out a video after the break of his computer running the greatest Infocom adventure, Hitchhiker’s Guide to the Galaxy.


  1. iHME says:

    This is sweet.
    I’ll be building myself one in the distant future.

  2. abobymouse says:

    I love builds like this. Awesome.

  3. John Boxall says:

    Nice build. Similar to the Australian Microbee systems of the late 1980s.

  4. lwatcdr says:

    So who is going to write the terminal for this? Maybe a Pic chip to bit bang out Video and interface to an old PS/2 keyboard?


    http://www.uxpro.com/cpm/www.cpm.z80.de/ has some links to CP/M Stuff. How about ZCPR? Anyone know that software is still lurking on the net?

  5. isama says:

    Wow, nice build! and I can’t believe i’ve never seen the 8080 portal video. now I really want to do something like that!

    Maybe something to learn netbsd with? or simply get it onto an arduino for pure lazyness :D

  6. willaim says:


  7. karl says:

    Hate to rain on anyones parade – it’s a nice build, but its difficult nowadays to find a floppy controler chip.

    • hboy007 says:

      There’s always a solution to deprecated logic chips: IP cores for FPGAs!
      A quick search brought up this discussion: http://www.vhdl-language.info/floppy-controller-in-vhdl

      I hope that in the future every standard IC will be available as a design, too.

      • nes says:

        I haven’t heard of anyone who’s done an HDL version of a floppy controller. Isn’t some sort of PLL part of the requirements which makes it tricky to do a generic FPGA core for?

        ISA bus super I/O chips, e.g. Winbond etc. are still available but AFAIK, they’re not format compatible with WD1797 used here, and you would need to find one which works off an 8-bit bus. You would get a couple of serial ports and a printer port for free though using one of those.

    • zacdee316 says:

      When there’s a need someone will fill it. Sooner or later someone will dig up the old schematics and start reproducing the chips for the DIY community.

  8. Alex says:

    Home built computers are one of my favorite things to see on hackaday.

  9. Ben Ryves says:

    Very nice work. :-)

    One of the advantages of CP/M 3 is that it no longer ties you to a physical disk sector size that matches the logical record size of 128 bytes. My Z80 computer runs CP/M 3 from an SD card, which has a 512 byte block size. As SD cards are inexpensive and easy to communicate with (SPI) I found this to be a much easier solution than trying to use a floppy disk drive.

  10. xorpunk says:

    Remembers doing a 20Mhz z80 and HTC TCIP stack based SBC way back..

    Nice to see something that isn’t content-marketing for arduino for a change..

  11. Buzzles says:

    Look at his desk, just look at it.

    Wire jungle springs to mind.

  12. Morgauxo says:

    I’ve never tried to make anything with a floppy controller chip so maybe I’m way off here but would old ISA floppy controllers contain the chips one needs for this? Those are anything but hard to come by!

  13. karl says:

    Morgauxo: If you can find one that’s only a floppy controller, or floppy + IDE – it should do the trick [look for a 44 pin SMD package or 40 pin DIP

    If it has “37C65″ as part of its part #, you should be OK.

  14. Miroslav says:

    Nice build. And CLI responds way faster than on a modern Windows/Linux (xterm) box. Something to ponder.

  15. APLFANBOI says:

    Floppies are BEAST! Still use em.

  16. willow says:

    I have a fully functional Osborn 2, haven’t touched it in years. Got it when I was like 11 or so to goof around with. Learned some DB coding just by plunking around.


  17. Orinoko says:

    Excellent build!! I really like how well the documentation is laid out and the circuit diagrams are easy to follow!!

  18. Chewie says:

    Just when I thought I was growing tired of HaD, stuff like this comes up. Nice work, I love it!

  19. marc says:

    If someone is interested to buy the floppy controller, I could have some of WD1770 for about $15, which is an equivalent to the IC mentioned in the project.

    If you are interested, leave a comment below.

  20. Willrandship says:

    It shouldn’t be too hard to throw the z80 port of BBC Basic on there. Then, you get a whole bunch of pre-existing programs at your disposal!

    And it’s code-compatible with your TI-84+ :P

  21. Some dude you don't know says:

    Man, would I love to make a MSX2 console, but I’m not sure if I have a Z80 chip lying around.

  22. Some dude you don't know says:

    Man, would I love to make a MSX2 console from this, but I’m not sure if I have a Z80 chip lying around. Also, I’m not very tech-savvy. :C

  23. i am going to build one. looks great.

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