Long story short.... The problem had to do with the way CPM & MS-DOS do disk sides. In CPM-86 I had 1-9 sectors on one side and for side B sectors were "called" 10-18. i.e. there was no special set side command. In MS-DOS of course the side in in DH.
I was at DRI when the decision was made about how to lay out the CP/M floppy disks. The difference between
the way Microsoft sees the floppy and the way DIgital Research sees the floppy, have to do with how IBM sees
Direct Access Storage Devices (DASD).
IBM reads all the data from all the heads of the device bore moving the heads to a new position.
This cuts down on the time necessary to format and read/write disk media because, when formatting for instance
the heads only have to pass across the disk once, and writes both sides as doing so. As opposed to the way
Microsoft sees the disk where the back is the second half of the drives.
By the way, you can tell a single sided CP/M disk from a double sided CP/M disk depending on the last
byte of the first sector on the second side, whether it is a 0x01 or not. (ohhh a secret!!!)
On Aug 21, 2011, at 10:40 AM, John Monahan wrote: