Disk drives with a 34-way data connector and 4-way power connector are pretty much the same. You can use drives from IBM PCs on a BBC, but not necessarily the other way around. Well, they'll work, sort of, but might not be readable anywhere else .....

IBM PC drives are double sided, 40 tracks. BBC Micro drives can be single or double sided, and 40 or 80 tracks. You shouldn't write 40-track disks on a 40/80-track switchable drive.

The BBC expects drives to be jumpered as 0 ("drive 2" is the other side of drive 0, if it has two heads) and 1 (similarly 3) whereas the PC expects both drives to be jumpered as 1 and uses a twist in the ribbon cable to swap over the select signals.

Also the BBC disks are formatted as ten sectors of 256 bytes, whereas MS-DOS uses 9 sectors of 512 bytes.





Good to note

You might need to check/jumper the correct use of pin 34. On the IBM-PC this is disk change. Most non PC systems use pin34 as a ready signal.

Older drives usually have a jumper to select this. New drives are usually for a PC and have pin 34 as disk change. As your drives started on the BBC micro they will be set for READY and need to be changed to DISK CHANGE. There is probably a jumper to do this.

I also think that the PC uses a stepping rate of 3ms for 80 track drives and 6ms for 40 track drives. Some BBC drives might not be able to step at this speed.