On Tue, Feb 06, 2001 at 10:31:42PM +0100, Alex Wulms wrote:
> In Sony machines and in NMS8245, some wd2793 registers (track, sector) are
> write only. In first version of fastcopy I mantained track number and sector
> number by just looking at the registers. This version did not work on Sony or
> NMS8245. Later, I corrected by maintaining track number and sector number in
> variables in the program and write them to the registers whenever needed.
>
> For the rest: 7FFD is a little bit more subtile:
> bit 1,0 : drive number
> bit 7: motor on/off (and not simply 'in use' led)
>
> Following bit table is applicable for the two drive number bits:
> B1 B0
> 0 0 : drive A selected
> 1 0 : drive A selected
> 0 1 : drive B selected
> 1 1 : no drive selected
Uhm once I connected two external drives to my Sony HB-F700P, which worked
fine. Possibly "1 0" is used for the third drive (if connected).
> And 7FFF is also wired (at least in Philips, I'm not sure anymore about Sony):
> bit 6: !INTRQ
> bit 7: !DTRQ
>
> I do not see a direct practicle usage for reading out the INTRQ and DTRQ
> signals of the wd2793 controller. But applications may exists that do rely on
> them so a perfect emulation should emulate these bits as well. But I think
> that in reality 99.999% of MSX software will work if you do not emulate them.
The NMS 8280 diskrom seems to use them. I've disassembled it a bit, and
another very interesting resource is the disassembly of the diskrom by
Alwin Henselaar:
http://huizen.dds.nl/~alwinh/msx/docs/index.htm
It is the NMS 8245 diskrom.
Alex, IIRC you had the datasheet for the Panasonic disk controller (TC8566),
do you happened to have scanned it?
Cheers,
Sean
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