A reader recently asked about the “native” format of Central Point Backup (CP Backup) floppies. Diskettes formatted in this manner are somewhat tricky to work with as they do not use a standard DOS format. A session with Sydex’s AnaDisk helped shed some light on this format. An old (1992) backup on 5¼” floppies was used for analysis.
When the DIR command is ran on a CP Backup floppy, a listing of largely zero-length files is shown. If the listing is not sorted (standard DOS behavior), a message spells out that the floppy does not use normal DOS format and needs to be reformatted for DOS use. If the directory listing is sorted (4DOS or similar), the message may prove difficult to decipher.
The above should imply that CP Backup formats floppies in a way that DOS can recognize, but not work with. AnaDisk immediately shows what the “problem” is: The 5¼” diskette is formatted with a standard BPB, FATs, and a root directory, but shows that all clusters are bad. What’s worse, the BPB indicates a standard 15 sectors per track (SPT) format, but in reality the diskette is formatted with 16 SPT. This will cause severe confusion to any tool (including DOS itself) which expects the BPB to reflect the true format. Continue reading
