Some points which may be of assistance: A long time ago, I built and maintained a PC-AT based system for reading/writing 8 inch diskettes. It used a 3rd party floppy controller card that supported FM mode(*), and an 8 inch drive from an AS/400. The crucial thing about the drive was that it was electrically "5.25 inch" compatible - it used the PC interface card-edge data cable and PC 12V/5V connector. In fact, it looked like an enlarged half-height 5.25 inch drive Several DOS disc copy programs of the era supported FM mode for 5.25 inch diskettes on a track-by-track basis, which therefore also worked for the 8 inch drive on 3740-format diskettes (index track FM, the rest MFM). I mainly used an IBM Internal program to handle reading/writing images in IBM's MIF format (an standard file format for storage and transmission of all forms of machine binary data, from punch cards to EPROM images to diskettes to tapes.) I gather from reading the archived thread that your requirements are somewhat more exacting, in that the density changes within a track (FM header and MFM data for each sector). Am I correct, or is it in fact just 3740 style (Track 0 FM, 1-73 MFM)? I have written code to operate the NEC 765 controller directly to handle unusual formats, but I've never tried mixed densities on one track. (*)The standard AT controller supported FM mode, too. I won't go into the history of PC controllers that did or did not support FM mode here, but the facts will be familiar to anyone who uses a PC to read/write 5.25 inch diskettes for BBC micros. -- Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand It's ironic that people who are too smart to engage in politics are governed by people who are not as smart.