<> The 1771 is a single density only controller and not suitable for use wit <> 3.5" disks. You want a board with a 765 (compupro) or 1793 CCS and a raf < <Are you claiming that you can't format/use a 3.5" disk at single density? <Now, I can't think of a machine that did, but equally I can't think of a <reason why you can't. The floppy drive really doesn't care how you One, at the lower data rates the 1771 is running below the 3.5" floppies 720khz rates and the 1771 does not do the faster one! So to be compatable with a 3.5" drive you need to run the 1771 at the 8" single density rate to get a something approximating 720k disk. At that rate your running at 250Kbits/Sec wich is the bottom data date for 3.5" floppies. Personally that is is a lot of effort as you will have to rewrite the bios for the different tracks/sectors and also allow for sides. OH, forgot that most SD controllers did only one side. If your going to the effort why not use a good DD controller and run the dsik up to the 1.44-1.6MB range? At that amount of storage CP/M feels like your using a slow hard disk. I know this from putting 3.5" floppies on my Vt180s, Ampro, Kaypro, SB180, CCS and compupro systems. All use 1793 or 765 DD controllers. Allison