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From: brianw@microsoft.UUCP (Brian Willoughby)
Newsgroups: comp.sys.apple
Subject: UniDisk or SmartPort on a card?
Summary: well...
Message-ID: <1190@microsoft.UUCP>
Date: 31 Mar 89 03:19:59 GMT
Organization: Microsoft Corp., Redmond WA
Lines: 45




I have a II+ with an AE TransWarp and I'd like to add 3.5" media to my arsenal.
I'm planning to buy a SCSI hard disk soon, and even though one Apple 3.5 drive
and II+ controller costs HALF the price of the hard disk, I still think that I
need a higher capacity REMOVABLE media. Especially considering that 3.5"
"floppies" have finally dropped to a reasonable price. I want to make smart
purchases, though, which will allow the hardware to be used on future systems.
The SCSI HD easily satifies this criteria because it will work on any Mac or
Apple II, but I want to get a 3.5" drive that will also easily move to a new
system.

Here are my questions/thoughts:

Why should I buy a UniDisk 3.5 for my II+, when all the new II's use the
Apple 3.5 Drive? My local Apple dealer stated that he thought the UniDisk
was only 400K like the original Mac.
What is the major difference between the UniDisk interface and the SmartPort? I
have for some time tried to determine why the UniDisk and Apple 3.5 Drive can
both be plugged into the GS, but I supposedly can't use the faster Apple 3.5
Drive on my II+. I understand that the UniDisk has a uP controller which adds
another level of indirection (and delay), where the Apple 3.5 Drive is just a
simple "dumb" drive (but faster). The UniDisk controller was obviously required
since the older Apples only understood 5.25"s.
Is there a SmartPort-on-a-card for the II+ (or //e)? What would prevent someone
from building such a beast? I have "hacked" most of the hardware on my system,
so performance outweighs the "lack of service" that I would experience by
building my own hardware (besides, I love a good hardware design problem).
Given the flexibilty of ProDOS 8, its seems that now the older Apple II+ could
easily access the Apple 3.5 if the proper driver were attached to a slot. If
ProDOS requires certain values in the $CnXX range to identify a SmartPort, then
I have a ROM burner card that works in my Apple to handle boot code.

If what I want (the Apple 3.5 Drive on a II+) is already possible, then please
correct my misunderstanding. Otherwise, does anyone know which Apple
documentation I could purchase that would allow the experienced (namely, me) to
put together a SmartPort on a card that would function with the Apple 3.5 Drive
and ProDOS 8 on a II+? Where can I learn about how the SmartPort interface
works?


Brian Willoughby                        microsoft!brianw@uunet.UU.NET
                or                      uw-beaver!microsoft!brianw
                or just                 microsoft!brianw