HP 9816 CP/M-68K

On 02/12/2018 12:23 PM, Fred Cisin via cctalk wrote: It's actually not too difficult. There were DOS utilities that could, for example, copy IBM XDF format. The trick is that on the 765 and its ilk, the FORMAT command writes sector headers according to the length parameter in the *command*, whereas the WRITE SECTOR command writes things out according to the length in the sector ID header. So, for example, you can specify that, say, 18 256 byte sectors are to be formatted, but each ID header would have a code of 3 or 1, indicating that the data part of the sector is 1024 or 256 bytes. Pick the appropriate sectors to write and you'll clobber any of the 256 byte ones that fall under the 1024 byte shadow of the larger ones. It does take a bit of planning, but it does work. In fact, this is a handy way to "wipe" a track free of any ID information at all. Just format up a couple of sectors with a length code of 6 or 7 and then write them. They'll eat their own heads, ignoring the index. FWIW, Chuck