Re: 5.25 drive emulator

[guertinp@IRO.UMontreal.CA (Paul Guertin)]

philip@labtam.oz.au writes:
>Ron "Asbestos" Dippold writes:
>
>>For a real 5.25 emulator, you'd need to intercept and emulate all the
>>bizarre Disk ][ ports and try to do something meaningful with them.
>
>  This wouldn't be impossible, but you would probably need to save your
>disk images as actual disk bytes so that you could emulate the raw reads
>and writes that the controller card does; this would increase the size
>of your disk image by a fair margin (approx. 350-400 bytes per sector
>rather than 256). 

It would have to be a lot more complicated than that if you want to 
truly emulate the Disk ][ and run copy-protected software. You'd have
to account for:

- Sync bytes vs. normal bytes
- Half-tracks, quarter-tracks
- Track synchronization 
- Physical damage to the disk

With a lot of work, you probably could do all these things. But it's
definitely non-trivial. If you want to do it without special hardware
to read the Apple disks, it becomes almost impossible.

Paul
guertinp@iro.umontreal.ca