AT&T 3B2 information

[Seth Morabito]

Folks,

For some reason I got it in my head that writing an AT&T 3B2 emulator
might be a good idea. That idea has pretty much been derailed by lack
of documentation.

I have been unable to find any detailed technical description of any
3B2 systems. Visual inspection of a 3B2 300 main board reveals the
following major components:

  - WE32100 CPU
  - WE32101 MMU
  - 4 x D2764A EPROM
  - TMS2797NL floppy disk controller
  - PD7261A hard disk controller
  - SCN2681A dual UART
  - AM9517A Multimode DMA Controller

How these are addressed is anybody's guess.

To even dream of doing an emulator, I at least need to know the system
memory map -- what physical addresses these devices map to. Without
that it's pretty pointless to get started.

If anyone has access to this kind of information, please drop me a
line. Otherwise, I'll just put this one on the far-back burner!

-Seth