Re: Platinum 3.5" 1.4 meg HD superdrive on Apple IIc

[shack@io.frii.com (Randy Shackelford)]

In article <63r3v1$t2k$1@lynx.unm.edu>,
stephen e buggie <buggie@musca.unm.edu> wrote:

>We all know that the Unidisk 3.5 800K capability can be added to an
>unenhanced original IIc by changing the ROM chip.
>
>What technical challenges must be overcome to add the platinum grey 3.5"
>1.4 meg "superdrive" to the IIC?   Would a ROM chip replacement suffice?
>If not, what else would it take?

You'd need a SWIM chip plus a way to connect it up. Also that chip likes
a 14 mHz clock signal. That's why the superdrive card has an oscillator
of that speed on board. And there's also a 65C02 on the card.

>Also, is there any way that a platinum 800K Apple 3.5 drive could be
>adapted for use on the IIC?  I know that its a timing problem because the
>grey 3.5 drive has a higher data transfer rate than the 1 meg
>unaccelerated IIc can handle.  The 65c02 inside the Unidisk 3.5 white case
>drive slows down the data transfer rate so the IIc can handle it.
>
>If thats the only problem, then why can't my  8 Mhz IIc-flagship handle
>the grey 3.5" drive???
>
>I have a IIC Plus 4 MHz, and its internal 3.5 drive is the grey version,
>and the db-19 drive port can handle the grey 3.5 drives.

The hardware is a bit different.

>We should do a big push to make possible the use of the grey Apple 3.5
>800K drive and also the 1.4 meg superdrive on the IIc.  Those drives are
>plentiful on the Mac groups.  The Unidisk 3.5 white drive will always be
>scarce.

They ain't that scarce, I think you're just looking in the wrong places. I'll
bet that Unidisks are more plentiful than external superdrives. These were
never big sellers since having two floppies on a Mac isn't necessary or even
overly useful. No Mac since '91 has had a port to plug one in. I quit looking
for one and swapped a superdrive mech into a grey 800K drive. At least you
can do that.
--
Randy Shackelford                                 
shack@frii.com