The AT&T 3B2/400 was a small, multi-user UNIX computer developed by AT&T in 1985. It was part of the larger 3B family of UNIX computers based on the Western Electric WE32000 and WE32100 series of CPUs and peripherals. What makes the 3B2 historically interesting was its use as the primary porting platform for AT&T UNIX System V Release 3.
This emulator is part of the SIMH simulation framework, and emulates a standard desktop 3B2/400 with the following devices:
- 1MB, 2MB, or 4MB of system memory
- One 720KB floppy diskette
- One or two 30MB, 72MB, or 161MB MFM hard disk drives.
Since internals documentation for the 3B2 series are not readily available, the emulator was made possible through a reverse-engineering effort, studying the System V Release 3 source code, and lots of caffeine.
- 2017-12-17: Minor compiler warning fix.
- 2017-12-16: Fixed a FIFO overflow bug in the CONTTY device.
- 2017-12-15: Critical MMU bugfix.
- 2017-12-13: Improved support for multiple hard disk drives, as well as adding support for additional hard disk geometries.
- 2017-12-09: Added support for the secondary on-board serial terminal (CONTTY).