FreeBee -- AT&T UNIX PC emulator

I'm developing an emulator for the AT&T UNIX PC. Currently it can boot the 3B1 UNIX operating system and run acceptably.

There are some documents and other items here which may be useful to 3B1 owners.

The emulator currently boots 3B1 UNIX, and thanks to the hard efforts of many people, can run a wide variety of software (including, thanks to Jesse, the C compiler and MGR windowing system!).

The serial ports, printer port and modem are not currently emulated. I'm currently looking for a good way to create a “virtual” serial port device on Linux, Windows and Mac OS X.

The source code is hosted on Github:

You will need the Boot ROMs to use this.

To install, build the code as per the README. You will need to compile the emulator, create a hard drive image, then follow the instructions in the AT&T manuals (on to install the System Software (in Imagedisk format at

You will need to use Imagedisk's “IMDU” utility to convert the IMD images into binary disk image files before using them with FreeBee.

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.

Jesse Booth put in a lot of time debugging and fixing the long-standing “PAGEIN” bug which prevented the C compiler from being used. Jesse also added support for the VIDPAL video PAL, and ImageDisk disk format support.

Boot ROMs.

This ZIP file contains binary and Intel Hex images 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.

    • AT&T System Software (Foundation Set) v3.0, v3.5 and v3.51 – Diagnostics, Floppy/Hard Disk Boot, Communications Patch, Curses/Terminfo, EIA RAM Combo Board drivers, Encryption Add-on, Telephone manager.
    • Electronic Mail
    • Personal Calendar
    • Tape Backup drivers
    • Utilities (Development Set)
      • Curses 3.51
      • Development Kit 3.51
      • Documentation 3.51
      • Editors and Window System 3.51
  • UNIX PC Information by Brian L. Stuart and Peter da Silva
    • An absolute treasure trove of UNIX PC software, including –
      • A mirror of the STORE archive
      • A mirror of the CalTech archive by Andy Fyfe
      • Indexed pages of software packages, sorted into categories
  • by Corey
    • 3B1 FAQ Rev 3 (1995) in text format
    • Software
      • Mirrors of the AT&T STORE archive, OSU archive, Caltech archive, comp.sources.3b1 (MISC directory)
      • AT&T floppy disk images
        • Foundation set, Communication Patch, Curses, Terminfo, Encryption, Document Preparation, Virtual Device and Development Set

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

Find me on Mastodon
  • Last modified: 2020/09/12 00:41
  • by philpem