I'm working in disk emulation via the wd2793 in mess. This will have far more
authentic emulation. First of all I'm working on emulating the Philips diskrom,
I've found the following:
Write:
7FF8: wd2793 command register
7FF9: wd2793 track register
7FFA: wd2793 sector register
7FFB: wd2793 data register
7FFC: side select. bit 0 : 0 => side 0, 1 => side 1
7FFD: drive select. bit 1-0 => drive. bit 7 => "in use" led
(led on if bit is set and right drive in bit 1-0).
7FFE: nothing
7FFF: nothing
Read:
7FF8: wd2793 status register
7FF9: wd2793 track register
7FFA: wd2793 sector register
7FFB: wd2793 data register
7FFC: bits 7-1 set, bit 0 is last value written
7FFD: bits 6-2 set, bit 7,1,0 is last value written
7FFE: unused (0xff)
7FFF: bits 5-0 set, bit 7 set if data request, bit 6 reset if interrupt request
Can someone verify the correctness of this? Also does anyone know if the
Sony machines use the same layout?
Cheers,
Sean
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