Apple IIc #8
Single-Sided 3.5" Media and the Apple IIc Plus

Written by Llew Roberts (May 1989)

This Technical Note describes a media limitation on the internal drive of the Apple IIc Plus.

With the exception of the internal drive on the Apple IIc Plus, single-sided 3.5" disks are supported on all Apple 3.5" drives, including external disk drives connected to an Apple IIc Plus. The IIc Plus internal disk drive assumes that all disks have an 800K capacity, so it returns valid reads on blocks which occur on the formatted side and I/O errors on blocks which occur on the unformatted side. A disk may appear to work when the disk-reading algorithm has read blocks only from the formatted side.

For these reasons, we suggest that you do not ship programs on single-sided media.

Further Reference

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