Re: Apple II 3.5" Controller and SuperDrive problems...

[pubpc1@library.ucla.edu]

Mitchell Spector wrote:
> 
> In article supertimer@aol.com (Supertimer) writes...
> 
> >Correct.  When the IIc Plus came along, it was fast enough to use
> >the GS & Macintosh style 3.5" drives.
> 
>     Increased speed was only part of the reason--it also had some
> extra circuitry added to the motherboard to help deal with data
> flow from an Apple 3.5 drive. There is the equivalent of a ZipChip
> built-in to the IIc Plus, and it takes more than just adding one
> of those to make the machine get along with "dumb" floppies drive.

Actually, no.  The increased speed would have enabled it to work
with the drives (you'd have to give it a GS IWM and take out all
the UniDisk junk first, though).  The high speed Laser computers
handle Apple 3.5 drives just fine and they do it faster than a
UDC (which needs extra circuitry for the slow 1MHz of the IIe).

The reason the IIc Plus has extra circuitry is because the logic
board still runs at 1MHz and that's because Apple originally
designed it as a 1MHz computer.  Later, as a second thought, they
added in the equivalent of a ZipChip (licensed firmware and
caching technology, even though the SRAM cache is separate in the
IIc Plus).  They already made most of the logic board work with
1MHz in mind, so in order to add speed they had to go the cache
accelerator method.  Kinda crazy, if you ask me.  They should
have had extra speed in mind first and made the entire logic
board go at 4MHz, like the Laser computers do.  If the logic
board operated at 4MHz, direct Apple 3.5 drive usage, like on
the IIgs, would be possible.

-Scott G.