Originally Posted by Olivier Galibert
You do whatever you want for you locally, of course, but I'm 98.5% certain there is no hardware in the nimbus to detect when a Dx value is written to the command register address and insert a bus delay in that case. So that wouldn't be accepted as-is, unless you have a way to prove there is such a thing.

Because my suggestions for altering the timing of the floppy code where 'rejected' and without them the machine's emulation doesn't work.

The Nimbus does inser 2 wait states in any transaction on the expansion bus (where the disk card is attached), However this only seems to have a significant effect on the force interrupt.

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As for the interrupt, the bios uses d0. That's a "gentle" interrupt we're probably running as too harsh, it's d8 that forces immediate stop. So I think we need to let the current action complete if it's a read or a write (not a search), which would probably do nicely with the rmnimbus.
I had implemented the write changes in the wd_fdc code, which seemed to work for writes as suggested in the other thread. I did try with reads but couldn't get it to work.


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The timing changes, otoh, why do you need them, what is happening in the bios?
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Not the bios but in the 'chipset' which as said above inserts wait states.

Cheers.

Phill.