Re: 3.5" + 5.25" drives?

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <4khd5e$cit@acme.freenet.columbus.oh.us>,
Dave Althoff <dalloff@freenet.columbus.oh.us> wrote:
> 
> Do any IIgs applications exist which actually care which version of the 3.5"
> disk drive they are using?

Definitely.  Anything which goes directly to the hardware or relies on
device-specific SmartPort calls will fail to work with the other type
of drive (or with a different controller in some cases).

For example, ZZCopy and similar programs will only work with Apple 3.5
Drives (or SuperDrives masquerading as Apple 3.5 Drives) connected to
the IIgs disk port.  FTA demos and similar programs are similarly
restricted.

The IIgs does a good job of making the UniDisk 3.5 and Apple 3.5 Drive
appear similar to applications, but this is only true for standard
SmartPort and ProDOS driver calls (or GS/OS applications).

> I thought that was only a hardware consideration, and that the IIgs
> SmartPort treats all 3.5" drives (whether UniDisk or Apple 3.5) as if
> they are Apple 3.5 drives. 

Nope.  The UniDisk 3.5 has no provision for allowing the computer to
bypass its internal processor.  The only supported communication
method is to sent SmartPort protocol packets to and from the drive.
The internal micro is responsible for accessing the disk.

(It is possible to download code into the UniDisk 3.5, which can then
access the disk directly.  There isn't much RAM in the drive, though,
so you can't do very much.)
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand