Apple IIc and 3.5 drives

[jimr@EICON.COM (Jim Royal)]

Someone asked a question about the Apple IIc and the use of 3.5 drives.

The only version of the IIc which is able to use the standard Apple 3.5 
Drive is the Apple IIc Plus.  All other versions, regardless of the ROM 
number, can only use the UniDisk 3.5 (which is getting more scarce all the 
time).

The UniDisk 3.5 is an intelligent drive, which means its controller card is 
built into the drive.  The Apple 3.5 Drive does not contain a controller 
card.  The UniDisk 3.5 is slower than the Apple 3.5 Drive because the 
controller circutry is an old, slow design.  Hence, the disk interleave on 
the UniDisk is, I believe, 4:1.  The disk interleave for the Apple 3.5 Drive 
is 2:1.  This makes the Apple 3.5 Drive twice as fast.

On the other hand, if all you've been using with your IIc are the 5.25 
drives, using the UniDisk 3.5 will be a real treat.

 Jim Royal
 jimr@eicon.com