Computie 68k

Description

A simple single board computer using a Motorola 68010 CPU, which can connect to a host computer via USB/TTL-Serial. It has a bus for connecting a supervisor arduino or expansion devices, but it can operate standalone using the onboard UARTs. It has 1MB of onboard Flash, 1MB of onboard SRAM, and a 68681 Dual UART chip with GPIO. Some of the GPIO pins are wired to 4 general purpose LEDs and 2 general purpose buttons. The SMT version has a CompactFlash socket directly interfaced to the CPU.

Along with it is a Unix-like OS that can do preemptive multitasking using the 68681 timer. It also has an implementation of the Minix version 1 filesystem, which uses RAM (through a device driver) to store the data, or a Compact Flash card connected as an IDE device. The second serial port can be configured as a SLIP device, with a basic implementation of UDP and TCP through a BSD sockets-style API, and an NTP command is provided for updating the system time on boot (when booting from disk).

Details

Project Logs

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Rev2, with Working CompactFlash
transistor_fet • 12/28/2022 at 20:33 • 0 comments

I've finally built a second revision of the latest board, which fixes the issue with the CompactFlash card's DSACK generation. See here for more details. With the latest board, it can now load and boot the kernel from the CompactFlash card. I fixed the mistaken footprints for the 74HC253 chips as well, and spaced the logic chips out more, to make it easier to assemble and bodge. It was a dream to assembly, by comparison to the first revision. I think it took me 4 to 6 hours in total, where the previous revision took 4 days of 6 - 8h each.

I honestly haven't touched it much after getting it working. I've been distracted by another project. But eventually I'll get around to modifying the kernel to allow virtual memory and isolated address spaces for processes, as well as work on the eventual multi-card computer version.
It Works!
transistor_fet • 12/18/2021 at 05:44 • 0 comments

The board will run the monitor software and boot the OS. I still have a problem with the CompactFlash card, but everything else seems to be working. I'm so happy, especially after making a mistake and using the wrong footprint for the two 16SSOP logic chips. I had to bend the pins under the package and try to solder them upside down, without hot air, just a fine tipped soldering iron.
k30-SBC Boards Are In
transistor_fet • 12/16/2021 at 06:14 • 0 comments

The k30-SBC boards arrived yesterday and the most minimal build to get the 68030 free running is working!

The oscilloscope screenshot shows address line 4 switching. Phew! My eyes are sore from looking at those fine pitched pins to inspect them. I'll finish the rest of it tomorrow
Moa - An Emulator for Computie
transistor_fet • 11/27/2021 at 02:50 • 0 comments

I've been working on an emulator written in Rust called Moa which is capable of emulating Computie. It will open two pseudoterminals on the host linux computer for the TTY and SLIP connections that Computie OS uses, and launches a terminal emulator to connect to the TTY. Check it out on github for more info
Bootstrapping a Homebuilt Computer Using An Arduino
transistor_fet • 09/10/2021 at 21:52 • 0 comments

I wrote a post about how I started this project, up until making the first PCB. Bootstrapping a Homebuilt Computer Using An Arduino Let me know what you think