AW: CGA card (Mitsubishi Electric) with 192K RAM?

Martin Peters martin at
Wed Sep 9 16:09:50 CDT 2020

Fred Cisin via cctalk:
> Got an IBM "Advanced Diagnostics" floppy to try?

If you want to do a ll-format, you only need debug:

-I 322      # reads dip-switches (don't think this is needed)
-I 321      # read status
-O 322 0    # select the controller
-I 321      # read status
-O 320 04   # ll-format instruction
-O 320 00   #   00 for drive C, 20 for drive D
-O 320 00
-O 320 00
-O 320 05
-O 320 07

the six "O 320" issue the "low-level format" instruction directly to the
controller. Bit 5 in 2nd byte represents the drive.

Do not expect any feedback, this is not a program, this is a direct
communication with the controller via in/out instructions. The ll-format
process is done in the controller's firmware and the Xebec-controllers
are very slow.

Martin Peters
martin at

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