View Full Version : Update on 3B2 emulator

January 20th, 2015, 12:27 PM
Hey all,

I just wanted to share an update on the current status of my 3B2 emulator.

I've been making a lot of good progress. I have enough of a WE32100 CPU core built to run the 3B2 firmware. It passes power-on self tests, and can run the built in firmware mode programs (like "version" and "edt"). See below:


I'm pretty excited about moving forward with it. It still has a long, long way to go before it can run UNIX. I've just started on implementing the floppy controller, that's my next goal.


January 20th, 2015, 01:37 PM
Nice! Congrats on the progress!

Rick Ethridge
January 20th, 2015, 08:46 PM
It looks good so far. It would be interesting to get it running here.

February 7th, 2015, 02:52 AM
it'd be nice if this could be run on PPC. emulating Unix on top of OSX 10.4 would be interesting.

Mike Chambers
February 8th, 2015, 04:20 PM
This is cool! I love emulation, will be following this.

February 9th, 2015, 12:23 PM
it'd be nice if this could be run on PPC. emulating Unix on top of OSX 10.4 would be interesting.

It looks like it's based on SIMH, which should compile just about anywhere. That said, I should try compiling SIMH from git on my 10.4 machines when I get home..

August 31st, 2015, 02:37 PM
It should be possible to adapt it into MAME/MESS CPU core (if suitably licensed) and then write a DMD5620 emulator... have you published your SIMH variant somewhere?

EDIT: ah, it's https://github.com/sethm/simh/tree/master/3B2

September 13th, 2015, 02:00 AM
I've cloned this for my work on 5620 emulation, found minor cpu core bugs and the progress so far is
https://img-fotki.yandex.ru/get/6440/264743.3/0_b13a8_251506ca_L.png (https://fotki.yandex.ru/next/users/shattered/album/137130/view/725928?ncrnd=649)
This scrambled display is supposed to say "KEYBOARD REQUESTED SELF-TEST" etc. Apparently a few more core bugs are lurking...

January 13th, 2016, 08:36 PM
This is a great idea, 3B2 seem pretty influential but are quite rare these days. Can you post a status update?

January 27th, 2016, 12:04 PM
Not sure what Seth is doing (latest from him is https://twitter.com/Twylo/status/655445059135930368 from 17 Oct 2015); I am using his code and SIMH now displays something sane, and accepts keyboard input:
https://img-fotki.yandex.ru/get/15517/264743.3/0_b13d2_d9c09004_L.png (https://fotki.yandex.ru/next/users/shattered/album/137130/view/725970?ncrnd=6773)

Next task is to hook up serial port to host; the terminal uses its 2681 DUART in a way that neither MAME nor SIMH currently emulates (OPCR is configured to send interrupt status to output port pins), and I've also stumbled over interrupt processing in the CPU core; hadn't touched the emulator since October, either.