Still seeking 3B2 information

Jerry Kemp other at
Tue Aug 11 09:36:36 CDT 2015

Hello Seth,

We were having a 3B2 discussion on the Sun Rescue list, and that got me to 
thinking about your emulator project.

Can you share a status update?

Is there anything us non-developers can do to assist?

Thank you,


On 01/19/15 01:45 PM, Seth Morabito wrote:
> Hi everyone,
> I've made tremendous progress on my 3B2 emulator. It's being
> implemented under the SIMH simulator platform, which has been a huge
> help.
> My WE32100 core is getting closer to being complete. I'd consider it
> alpha quality right now, but it has enough instruction coverage to
> pass the 3B2's power-on self tests and to (barely) run some of the 3B2
> firmware mode tools.
> Implementing the WE32100 core has been thanks to the processor manual
> and assembly language manuals that are available on BitSavers, but
> outside of the CPU, virtually all of my understanding of the 3B2's
> architecture has come from studying the ROMs and the SYSVR3 source
> code. I've also been helped by having remote access to a running 3B2
> so I can assemble and disassemble code using the real AT&T tools.
> Beyond that, I have found precious little documentation.
> I'm at the point now where I'm pretty well stuck until I can find more
> information. I understand large chunks of the memory map now and
> should be able to do things like simulate the floppy and hard disk
> controller, but there are large gaps in my understanding. There are
> many undocumented registers that are used by the firmware, but don't
> appear in the SYSV source code anywhere. What they mean and what
> they're for is anybody's guess. I've just stubbed them out for now.
> If anybody has access to schematics, architecture docs, or other
> memory map information, I'd be eternally grateful if you could share
> it!
> -Seth

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