25-04-2026, 08:05 PM
There is a lot of source code for formatting floppy drives on the various cpm resource sites. Have a look at how a floppy is formatted, I'd speculate that it is pretty similar to how the HD were formatted. Then have a look at the cf bios code, there is a format code in there and partition code that runs on both ide and cf. The underlying media only has impact at lower level.
I suspect you're thinking more of partitioning rather than the dpb.
Original cpm code worked with 128byte sectors, then mostly changed to 512 byte sectors by adding blocking/deblocking code (also fairly well documented in cpm manuals online). Apart from much later homebrew systems, hd used c/h/s but now we add partition tables as another layer. Each partition is effectively the same as a big floppy disk from the user api point of view.
Much of this bled into msdos so the descriptions of how that works is pretty similar.
With that info on board, working out how the init.com works will be a little clearer. Keep in mind the year that this stuff was written and the hardware that it as used on, the concepts that were known then aren't always the same as we have had since then.
Good luck
gb
aka Rod
I suspect you're thinking more of partitioning rather than the dpb.
Original cpm code worked with 128byte sectors, then mostly changed to 512 byte sectors by adding blocking/deblocking code (also fairly well documented in cpm manuals online). Apart from much later homebrew systems, hd used c/h/s but now we add partition tables as another layer. Each partition is effectively the same as a big floppy disk from the user api point of view.
Much of this bled into msdos so the descriptions of how that works is pretty similar.
With that info on board, working out how the init.com works will be a little clearer. Keep in mind the year that this stuff was written and the hardware that it as used on, the concepts that were known then aren't always the same as we have had since then.
Good luck
gb
aka Rod