(2020)

Previously:

https://news.ycombinator.com/item?id=24680109

That reminds me of a three week, three person group project I had back when I was in university. There were a couple of topics we could pick from, including writing a very simple operating system from scratch. I asked the professors if we could instead port MINIX3 to the Raspberry Pi (given that it already had an ARM port to the BeagleBoard) and they accepted.

What was supposed to be a reasonably straightforward project proved to be a huge challenge as we encountered numerous unforeseen technical difficulties. One particularly harrowing one was that the Raspberry Pi 3 booted into hypervisor mode instead of supervisor mode and QEMU's Raspberry Pi emulation accuracy was so abysmal back then to be borderline useless for osdev. I recall it took me an entire week of low-level hardware debugging just to figure that one out.

By the end, we pulled through and delivered a working port with UART, GPIO and framebuffer drivers that could run on the Raspberry Pi 2 and 3. We run our presentation with the port on real hardware, using a shell script that displayed bitmaps from the ramdisk and monitored GPIO pins to move slides forwards or backwards (I used a knife to short-circuit the pins as needed). It was by far the coolest presentation of all the groups just on originality alone and I think I still have the image of that SD card somewhere.

Very impressive! Low end work is often tedious and time consuming, especially if you lack the essentials like a debugger.

We did this sort of thing at SFU some 25-30 years ago; though we stopped short of running an OS and compiler on it, and it wasn't a group project.

For those interesting in trying this sort of experiment, but wish to have some guidance and accessible tooling, I highly recommend Turing Complete; you'll go from a few gates to a full computer. Components can be shared with the community; where you'll find things like a RiscV core and such. Anyhow, it's great fun. Do recommend. It's on Steam:

https://store.steampowered.com/app/1444480/Turing_Complete/

Magic-1 and BMOW did similar, a while back. See: https://www.homebrewcpu.com/

The actual list of sites who have built their own CPUs: https://www.homebrewcpuring.org/

Now they gotta run to the semiconductor lab and get them to fabricate the CPU instead of configuring an FPGA to run it.

This reminds me of a kind of similar academic(?) project that at the very least had a custom C compiler alongside a custom OS… I can’t remember what it is offhand though.

One of my favourite 8-bit computers of the era is the Oric-1/Atmos micro.

https://en.wikipedia.org/wiki/Oric_(computer)

It still to this day has a thriving scene, lots of interesting quirky programs still being written for it. (https://oric.org/)

There is also a thriving hardware hacking scene of course, 21st century peripherals being brought to the user base, and so on.

One of the more interesting things (besides LOCI), is the orix system, which is a 'unix-like' environment for the Oric, which uses avariant of the 6502 cpu.

Its pretty cool - and fun if you're an Oric nerd - but if you like 'unix-like' systems for unusual platforms, put this one in your list to check out, as well:

https://orix.oric.org

https://orix.oric.org/twilighte-board-v0-6-user-manual/

Oh, yeah, I know 'unix-like' has a wide scale of sincerity, this is not quite there .. yet .. in terms of having all the unix bits, really .. but it is at least bootstrap in that kind of direction, for the Oric .. anyway ..

Maybe I missed it but which FPGA did they use for this? I’m interested in learning FPGAs but there doesn’t seem to be a lot of freewheel documentation or software out there, it’s mostly vendor locked. I’m spoiled by the availability of STM32, AT, TI, etc MCUs and how easy it is to kludge things together.

I wish I could do something like this.