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CP/M disk format question
- Subject: CP/M disk format question
- From: Andy McFadden <fadden@fadden.com>
- Date: 11 Jul 2008 17:59:58 GMT
- Newsgroups: comp.sys.apple2
- Organization: faddenInternet, Inc.
- User-agent: tin/1.9.2-20070201 ("Dalaruan") (UNIX) (Linux/2.6.24-19-generic (i686))
- Xref: g2news2.google.com comp.sys.apple2:10927
All of this is in the context of Apple II CP/M on a 5.25 floppy.
CP/M disks use 1K blocks, and have a directory starting at block 12 (track 3
on a 5.25" disk). The first 3 tracks are reserved for the boot image. That
leaves 140K - 12K = 128 blocks.
I've been sent an apparently valid disk image that uses block numbers above
128. It appears that such values wrap around, storing data in track 0-2.
Is this the expected behavior? This is of interest for the CiderPress
disk read routines, which are currently unable to extract such a file
in its entirety.
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