I/O port 0170H refers to the secondary *hard drive* address (the primary being 01f0H). The secondary FDC address is 037xH (the primary is 03FxH). Let me look around--I've got several old MS-DOS secondary port drivers kicking around here. A word of warning, however. For a secondary controller using the same DMA and IRQ (2 and 6) as the primary, the primary needs to have implemented the "enable" bit at I/O port 03F2H so it can float its own DMA and IRQ lines when the secondary controller is active. Not all controllers will do this, even though it's documented as part of the standard PC architecture. If you want to check out the operation of your secondary controller, hook a drive to it and find copy of FORMATQM or COPYQM (or 22DISK...) and set up a DISKETTE.CFG file for it to use. In the meantime, I'll look for a good driver. Cheers, Chuck