Disk Drive Tech Info GS<->Mac

[figueirp@ecs.ecs.csus.edu (Paulo Figueiredo)]

Hello.  I need the help of the technically gifted:

Why won't a macintosh 800K External drive (beige) work on an Apple IIgs?
I have looked at the diagrams for the ports and MOST of the pins
are the same on both machines.  The main catch (I think) is the PWM
output on the mac, which I don't see on the GS.

More importantly, I have an Apple HD 20 (connects though the Mac's drive
port) that I'd like to use on the IIgs.  Would a HD need the PWM signal?
I thought it would be smart enough to take care of its own timing.

Finally, if it is just a matter of driver software, what's required?
Does a driver already exist?  How difficult is it to write one?

Thanks for the help,

Dennis (djc@altair.csustan.edu)
NOTE: Please send to above address -- I am posting from a friend's account.