KryoFlux - Apple DOS 3.3 / ProDOS Sector Image Support


Apple DOS3.3/ProDOS sector dumps supported.

Note that disk images do not use the real physical sector order on the disk; the only difference between DOS3.3 and ProDOS (in terms of the direct physical format of the data) is the way the order of the sectors on a track get interleaved and paired. A DTC sector dump always reflects the sector order as specified the lowest level of disk access of the target system without any upper level OS additions, I.e. as sector numbers specified on the disk. On the other hand Apple disk images use the predefined interleave/pairing of DOS 3.3 or ProDOS... Therefore to make a DSK image the sectors in the sector dump have to be re-arranged to the desired format.

It may be an option to create one of those at a later time - however given that the data order is not altered in any way by DTC it’s easy to do. We could add a DOS 3.3 sector re-arrange easily - in fact we have a hack that does that to verify against known good images. We’d need to have disks imaged as ProDOS to verify the ordering generated by ProDOS imagers.

Copy protection was very popular on these systems. Piracy was rampant, and nybblers and the like were very imaginative... We went through tons of articles and even the firmware used by the drives to add this support. Block decoding is practically what the Apple drive hardware and firmware does (they are very tightly coupled) - plus tons of error checking for what it does not :). We spent probably more time adding support for this system than any platform so far.