BMOW: A Home Made Cpu


Building your own CPU sounds like quite a daunting task as it is. Building your own CPU using manual wire wrapping transcends difficult to become an art form. [Steve] has built a CPU by manually wrapping every single wire. That’s 1253 wires, or 2506 wrapped ends. Even if it didn’t work, it would be nice to look at. But it does work, you can see a demo video showing the audio functions after the break. The system is now enclosed in an Acer x-terminal case, so it isn’t as pretty, but its still quite a project. You can follow along as he builds each section, the video, sound, even the keyboard interface. It’s pretty amazing seeing it all broken down to the most basic forms.


[thanks Ben]

34 thoughts on “BMOW: A Home Made Cpu

  1. Yay. I’ve been following this since he first started. I am actually just getting started on a similar project. (7400 logic gates for a CPU. I myself will be doing point-to-point soldering… Blah! Soldering is already a huge chore :P)

  2. yeah, that’s just nuts. i wonder what can drive a person to do a thing like this. serious ocd? lots of caffeine? i mean, maybe if my xbox broke, and internet porn stopped working… idk

  3. awesome. . .but he used programmable logic (22V10s in schematic)! Would have been even cooler (and about three orders of magnitude more insane) to use pure 74xx series logic ;P

    just kidding, of course–probably would have been 10,000+ connections at that point =P awesome project!

  4. This is not a CPU. Go Wiki it. A wire wrapped CPU? That would be 1000x times more impressive. Nice enough, reminds me of projects me and my brother did in the 90’s. Ah, Hex codes & machine language. Z80’s rule..

  5. Thanks for all the comments! BMOW is my project, and I’ve been working on it for over a year now. I spend a couple of hours here and there on evenings and weekends, and yes I have a regular job, family, and kids! As to why anyone would do this, um, you’ve got me there. Yes it is a real custom CPU, along with custom video display and audio circuitry, keyboard interface, and so on. It’s a mix of 74xx parts, 22v10s, and a few purpose-specific chips for audio and video. It all adds up to something vaguely like an Apple II.

  6. The point is, the knowledge of HOW basic elements of our technology work is becoming a rare commodity. If there is a major disruption to the Asian Tech Umbilical Cord, being able to keep things going will require people who can design and repair down down to the component level. Ham radio operators have known this for decades.

  7. awesome work mate, i love the 3 voice audio too! reminds me alot of the simpler times…

    A mate of mine has been working on something similar over at, cept he cheated and soldered point to point, however he made his own bus system. it was the same machine that was used in the 8080 Still Alive (portal) video on youtube.

    love ya work, keep it up!

  8. The comment RE: “Basic elements of how..” is an understatement. The Flying Spaghetti Monster will not touch us with his noodly appendage to impart know-how. Hell, even Galena crystal “Cat’s Whisker” radios have become a rarely touched tech. Arguably that Galena crystal would not be allowed into my grandson’s school as it’s a lead exposure risk.. Of course a rusty razor blade makes a lovely detector diode too. So a wirewrap cpu is a tech bridge between the TTL and System-on-chip realms. Look back to making a cpu with discrete germanium transistors for example further. Or even making a germanium active device at the home hacker level!

  9. One bloke I used to work for, built a graphics processor for a head mounted display system, back in the early 90s, as part of his masters degree. The rig consisted of around 6 wire wrap boards (maybe more), each about 50x50cm in size. It was very impressive, it had its own dedicated multiplier circuits and other crazy arithmetic functions consisting of discrete chips.

  10. programmable logic chips? please.

    I owned a few of these in the past, that’s where you can really get some appreciation for wire-wrapping and detailed logic. And core memory!

    Among other features were the front panel with a separate light for EVERYTHING (not like the PDP-8/e which used a single row of indicators and a rotary selector so you could only see one “batch” at a time) and fully variable speed from one instruction per minute or whatever up to full, and with LINC mode it could boot from a magnetic tape with a single command from the front panel.

    The CRT tube (worked like an oscilliscope, all text characters had to be “Drawn”) could be used as a “terminal display” with only the keyboard of the usual printing terminal (teletype) used for input, saves a lot of paper that way!

    Being a “lab” machine it had A/D and D/A connections plus binding posts to six SPDT relays
    which also each had their own indicator lights on the panel!

    And all of the logic was discrete, each register was broken down and two bits of each was on a separate flip-chip card wire-wrapped to the others!

    Great old systems, wish I still had one just to show the fancy-pants kids…

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