Re: Laser UDC Documentation

["David Wilson" <mcs6502@gmail.com>]

Steven N. Hirsch wrote:
> Warren Ernst wrote:
> > Though it was supposed to work, I *never* got an Apple 3.5" drive (the
> > platinum the GS uses) to work with an enhanced //e with the Laser UDC.
> >
> > I *did*, however, get the older-style 800k macintosh 3.5 drives
> > (without the eject button) to work with it, which was kind of neat.

> There are at least (2) distinct ROM versions for the UDC controller.  On
> of them supported the Unidisk 3.5 (original Apple 3.5" drive for IIe and
> IIc) and one supported the later Apple Disk 3.5.  AFAIK they are
> interchangable on all the UDC hardware levels.

My UDC is the later hardware version (QFP chip and two D-19F cables)
and I tried a borrowed UniDisk 3.5 on it with no success. It certainly
has no problem driving an Apple 3.5 on my enhanced IIe and was able to
drive a Macintosh 800KB 3.5" drive (but very slowly). I have patched
the firmware on my UDC to treat all 5.25" drives as 40 track 160KB
units.