> > We have a collection of test programs stored on 8" floppies which were

Well, I have the SA850 service manual somewhere. I could probably even find it... But it's not going to help with the format information. 8" disk drives, like virtually all floppy drvies have a 'raw' (low level) interface. It's up to the _controller_ to determine the format. The disks could be soft-sectored (one hole for the index sensor) or hard sectored (one hole for the start of each track, evenly spaced, and one hole midway between 2 of them for the index). The data could be recorded using FM encoding ('single density'), MFM encoding ('double density') or a number of other less widely-used methods (MMFM, GCR, etc). Even when you've worked out those details, you still have to find the number of sectors/track, the size of each sector, and other similar information. If the controller was custom (as opposed to using one of the standard disk controller chips) then the sector headers could be just about anything. Heck, I've seen machines using FM encoding for the headers and MFM encoding for the data... And after that you've only managed to read raw sectors. You then have to work out what sectors make up a given file -- things like the directory format (assuming there is a directory), etc. The best place to start looking would be in the service manual/schematics for the instrument itself. You should be able to work out what the very -tony