[Coco] MAME FDC Issue that can cause corruption

[Allen Huffman]

> On Aug 2, 2017, at 3:31 AM, Ciaran Anscomb <cocomalt at 6809.org.uk> wrote:
> 
> So what's the behaviour of real drives?  Is there really a delay before
> the ready signal is updated on switching drives?

This reminds me of an issue with the old Mac Virtual PC from Connectix (before Microsoft bought them). The floppy driver worked fine for DOS, but wouldn't boot OS-9000. I worked for Microware at the time, and somehow got in touch with a lead engineer there (I don't think it was Microsoft yet, but maybe it was).

There was some status bit OS-9000 was reading and using which the emulator did not implement because DOS did not use it. Microware coded to spec, while the emulator coded to usage.

I send them a boot disk with the "ROM" debugger available and they were able to figure this out and fix it.

I wonder now if RS-DOS isn't the "DOS" in this MAME example and the MAME contributors are the "Microware" (coding to spec).

		-- A