Connecting a 3.5" drive to an Apple //c

Copyright (c) 1994 Apple Users' Group, Sydney
Republished from Applecations, a publication of the Apple Users' Group, Sydney, Australia.

Source Internet, edited for publication

Q: Which 3.5" drive can I connect to my Apple IIc?

The only version of the Apple IIc which is able to use the standard Apple 3.5" Drive is the Apple IIc+ (available only in North America). All other versions, regardless of the ROM number, can only use the UniDisk 3.5" drive.

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 it reads individual disk blocks into RAM within the drive, then transfers them to the computer. The UniDisk 3.5 also has a slower data transfer rate between the drive and the computer.

If the value of $FBBF (PEEK(64447)) is $FF (255) then you will also need a ROM upgrade to be able to use the UniDisk 3.5" drive. This ROM upgrade was readily available from Apple re-sellers.

Thanks to:
Jim Royal    jimr@eicon.com
David Empson    dempson@swell.actrix.gen.nz


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