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4 commits

Author SHA1 Message Date
Seth Morabito
9d849283a4 3B2: Interrupt Refactor and DEMON ROM
- This change introduces a full refactor of the interrupt subsystem
  for the system board (SBD) and the I/O bus (CIO). Interrupt decode
  should now be significantly faster, and not require an expensive
  calculation on every step.

- The TIMER device has been split into Rev 2 and Rev 3
  implementations.

- The optional 3B2/400 Debug Monitor ROMs can now be booted by passing
  the "DEMON" argument to the 3B2/400 simulator BOOT command. Any
  of the following will cause the Debug Monitor ROM to be booted
  instead of the standard 3B2/400 ROM:

     sim> BOOT DEMON
     sim> BOOT CPU DEMON
     sim> BOOT DEMON CPU
2021-08-24 06:35:49 -07:00
Seth Morabito
ae0cad26e4 3b2: Make floppy controller a DEV_DISK device
- Formerly, the floppy controller buffered an entire diskette image
  in memory using the unit buffer, and flushed it out on detach or
  shutdown. This worked well enough, but it's better to have the
  device use the SIMH disk sector read and write routines and
  behave like a true disk.

- Read Only (Write Protect) logic has also been enabled in the
  floppy controller, allowing users to mount images that do not
  have write permissions.

- The IF (Integrated Floppy) and ID (Integrated Disk)
  device names were poorly chosen. They conflict with built-in
  scp commands and mess up the help system. This commit
  changes them to IFLOPPY and IDISK, respectively.

  NOTE!! THIS IS A BREAKING CONFIG CHANGE!!
2019-01-13 22:25:26 -08:00
Seth Morabito
22b8e211c6 3b2: Improve TOD calculation 2017-11-29 21:44:40 +00:00
Seth Morabito
804ea8e322 3b2: Initial release of an AT&T 3B2 model 400 emulator.
For information on usage, please see the file 3B2/README.md
2017-11-20 18:21:49 -08:00