This is an old revision of the document!


FreeBee -- AT&T UNIX PC emulator

:!: insert screenshot here

I'm currently working on an emulator for the AT&T 3B1 Unix PC. I haven't released any stable code yet, though the Mercurial repository is publicly-accessible. There are some documents and other items here which may be useful to 3B1 owners…

The 3B1 emulator would not be possible without the generous donation of two AT&T UNIX PC systems and software disks by Antoni Sawicki.

Andrew Warkentin has contributed many significant patches which improve the quality of the emulation and allow UNIX to be booted inside the emulator.

Boots 3B1 UNIX, with occasional errors. The C compiler causes memory paging errors, and seems to be a bit finicky.

I'd like to try and integrate FreeBee into MAME, which might help improve the CPU emulation.

AT&T 3B1 Boot ROMs / ROM set. Images (binary and Intel Hex) of the two 3B1 Boot ROMs. These are fitted at board locations 14C and 15C, and carry part numbers 72-00616 and 72-00617 respectively.

Steven Hirsch scanned the entire of the two-binder AT&T 3B1 Unix PC Technical Reference, and released them on the Classic Computers Mailing List. With his permission, the scans are mirrored here:

  • AT&T UNIX PC Reference Manual (chapters 1 and 2)
  • AT&T UNIX PC Reference Manual (chapters 3 and 4)
  • AT&T UNIX PC Reference Manual (appendix A: PAL equations)
  • AT&T UNIX PC Reference Manual (appendix B: Mnemonics)
  • AT&T UNIX PC Reference Manual (appendix C: Expansion memory locations)
  • AT&T UNIX PC Reference Manual (International Version Supplement)
  • AT&T UNIX PC Schematics: D-08-00222-00 “Schematic: S4, CPU”; alternate versions: 1, 2
  • AT&T UNIX PC Schematics: D-32-00379-00 “DMA Address I.C.”
  • AT&T UNIX PC Schematics: D-32-00381-00 “Video I.C.”
  • DOS-73 Technical Reference (no schematics)
  • Ethernet Expansion Board: Theory of Operation (includes schematics)
  • Floppy Tape Interface: Theory of Operation (includes schematics)
  • RAM-COMM Expansion Board: Theory of Operation (includes schematics)
  • AT&T S4BUS – UNIX PC Expansion Bus Specifications, Issue 1.3
Find me on Mastodon
  • Last modified: 2020/01/26 14:36
  • by philpem