Re: Commodore 64 kills APPLE II

[mjmahon@aol.com (Michael J. Mahon)]

Roger Johnstone wrote:

>Dave Althoff Jr wrote:
>
> > Martin (martinf@ot.com.au) wrote:
> >
> > : (2) Disk drives. The apple disk drives beat the commodore range
> > hands down ! : I have numerous Commodore drives at home (1541, 1571,
> > 1581) for my C64s and : 128s and everything I have available for my
> > apples (Duo Disk on the IIe and : 5.25" & 3.5" Apple drives on the
> > IIgs) is much faster and more compact than : the commodore beasts !
> >
> > Yeah, but how many Apple drives are progrmmable?  8-)
> >
> > --Dave Althoff, ][.  <- You can see where my biases are...
> >
>
>The Apple UniDisk 3.5 is programmable. It has it's own processor and
>enough RAM to hold a program sent to it from the host computer.

It is my understanding that the UniDisk 3.5 is a smartport device.
So the question is whether there is a command implemented in
its firmware that allows transfer of control to a program stored in
its SRAM.

>The Apple IIgs is fast enough to control the 3.5" disk drive directly,
>so the Apple 3.5 Drive doesn't have a processor. However, the IIgs can
>store the same routines in it's own memory and run them in the same way
>as the processor in the UniDisk 3.5 does.
>
>That said, does anyone know if any software used this ability, rather
>than just using the routines in ROM? Copy protection schemes perhaps?

All the usual tricks permitted by the SWIM chip, which has capabilities
and limitations very similar to the Disk ][ controller, though at a higher
data rate.

I'm unaware of the full panoply of copy protection tricks employed
on 5.25" disks being applied to 3.5" disks, however.  Is there some
limitation on direct control of the head positioning motor on the 3.5"
drive?  (Or had the industry simply outgrown most of that by the
time the IIgs and 3.5" drive became common?)

-michael

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