This is a 16bit CPU+Minicomputer from pure 74 series logic. It has user/kernel modes, virtual memory, prioritized IRQ's and DMA. It has a full C compiler and a unix-like OS. It's still in development.
Sometimes I feel bad for kids today who experience computers that are so powerful that they are many layers divorced from the hardware. Long gone are the days when there was only the thinnest layer of BASIC between you and the CPU when you boot the machine.
But then something like this comes along and reminds me that there is no reason you can't just fire up a 16 bit machine with a paper thin OS if you wanted. Not everything has to be a smartphone or modern system. My hat is off to the author for going a step further and building a minicomputer from scratch.
Wow; this looks a lot like the smaller PDP-11 minis from the 1970s: a stack of wire-wrapped cards with edge connectors plugged into a backplane, a few ribbon cables for other connections. Except DEC had a big team of engineers to do this. This is good stuff!
What was your workflow for the design like? On your github I see you used verilog. I have never used it. Do you use software that converts the verilog to a list of 74HC ICs and how to connect them?
Some fun historical context: the 74181 chip (part of the 74HC series) was one of the key technologies behind the Xerox Alto. It was the first complete ALU on a single chip using a medium-scale integration (MSI) design. This was what enabled the Alto to be much smaller than minicomputers like the PDP-8, which used small-scale integration (SSI) that spread the processor over many individual logic gate chips and circuit boards.
I adore this project. I hope one day to write my own micro OS, I started one using OSDev[0], but never finished it. Building your own OS on top of your own hardware is on another level though. Excellent and nicely documented project, Paulo!
This is fun, I stumbled upon his youtube channel recently after he trash talked a lecture by Jan M. Rabaey calling his book the biggest piece of garbage ever written.
Impressive stuff nonetheless.
I would follow you on Twitter/X as well -- but you don't seem to have a Twitter/X account (which I would argue is yet more proof of your intelligence! :-) <g> :-) )
Sir, this is incredible. Really enjoyed the photos/videos section and the way the computer is so neatly laid out. Mind-blowing amount of effort. I wish I would be able to see this live in a university.
I didn't mean to imply that they are abnormal, just that they are large and large boards like that tend to be harder to make stable when using wire wrap as a technique. I've done this - and stacks of them too - but I've also spent days tracing a faulty wire, and the chance of such faults goes up as the number of wires goes up.
I've worked on similar projects before and people always suggest FPGAs to me as a simpler option, but I feel it misses the point. Doing these kinds of projects is about getting closer to the metal, and not about raw power or simplicity
Should definitely be possible with mostly static content and Cloudflare caches in front. I bet there are many personal websites out there served from an old smartphone or from a Raspberry Pi Zero.
This is spectacular. Aside from, you know, actually making it work and having a software stack on top of it, it’s also beautiful. The wire wrapping and the chassis/backplane complete with retaining clips, everything.
As a kid, I would see magazine photos of S-100 systems and various minis. What’s been built here would fit right in. Wow!
