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Thread: Update on 3B2 emulator

  1. #1

    Default Update on 3B2 emulator

    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.

    Seth Morabito
    Commodore and DEC Enthusiast
    Poulsbo, WA, USA

  2. #2
    Join Date
    Jan 2014
    Northfield, MN USA


    Nice! Congrats on the progress!

  3. #3
    Join Date
    Nov 2003
    Plattsmouth, Nebraska USA
    Blog Entries


    It looks good so far. It would be interesting to get it running here.
    Rick Ethridge

  4. #4


    it'd be nice if this could be run on PPC. emulating Unix on top of OSX 10.4 would be interesting.

  5. #5


    This is cool! I love emulation, will be following this.
    My emulators!
    Fake86 8086/V20 PC emulator:
    MoarNES Nintendo emulator:

  6. #6


    Quote Originally Posted by super-sama View Post
    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..

  7. #7


    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
    Last edited by shattered; September 1st, 2015 at 11:47 AM.

  8. #8


    I've cloned this for my work on 5620 emulation, found minor cpu core bugs and the progress so far is

    This scrambled display is supposed to say "KEYBOARD REQUESTED SELF-TEST" etc. Apparently a few more core bugs are lurking...
    Last edited by shattered; September 14th, 2015 at 02:32 PM.

  9. #9


    This is a great idea, 3B2 seem pretty influential but are quite rare these days. Can you post a status update?

  10. #10


    Not sure what Seth is doing (latest from him is from 17 Oct 2015); I am using his code and SIMH now displays something sane, and accepts keyboard input:

    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.


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