Re: Old non-SCSI Mac hard drive on IIc?

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

In article <4s4i1r$2qq@blackice.winternet.com>, nathan@parka.winternet.com
(Nathan Mates) wrote:

>In article <4s44gh$3lr@wraith.cs.uow.edu.au>,
>David E A Wilson <david@wraith.cs.uow.edu.au> wrote:
>>No Macintosh devices are SmartPort to my knowledge (on the Apple II the only
>>Apple SmartPort product is the UniDisk 3.5  [snip]
>
>   There's the Unidisk 3.5, the Appledisk 3.5 (platinum), the 3.5 HD
>(High Density-1.44MB), the Chinook external HD for the //c, and
>probably a few more.

The Apple 3.5 Drive and SuperDrive are not SmartPort devices (i.e. they
don't use the SmartPort protocol), and neither are the Mac 400K and 800K
drives.  For 400K/800K disks, they all work in a similar way to the
original Apple 5.25" drives for data transfer (just at twice the bit
rate).  Operations like track stepping are performed by accessing 1-bit
registers in the drive, using the phase lines for register selection.

By comparison, the SmartPort protocol streams packetised data down the
read and write data lines of the bus, at 4 microseconds per bit.

>The Mac 400K and 800K drives should work fine (my Appledisk 3.5"
>manual said that it should work on both, but the eject button was
>disabled on the mac side), along with a bunch more. 

The Apple 3.5 Drive was specially designed to work on the IIgs and Mac
disk ports. The Mac 400K and 800K drives do not work on the IIgs disk
port. There are at least two signals missing: the 'I am a 3.5" drive'
signal from the drive, and the timing signal from the computer which
controls the disk rotation speed (this is built into the Apple 3.5 Drive).

I'm not sure if the Mac 800K drive needs the timing signal, but it still
doesn't work on the IIgs (I tried one).

Both of these drives work with a Universal Disk Controller card, but
nothing else (I don't know if the SuperDrive card supports them, but I
doubt it).

-- 
David Empson
dempson@actrix.gen.nz
Snail Mail: P.O. Box 27-103, Wellington, NEW ZEALAND