Now that I know the 765 better - makes perfect sense. This is a good example of the problems I had with the NEC documention when I originally wrote the 6809 driver (mid 80's - my first experience with the 765). There are very few references to polled transfers. Under "READ DATA", the datasheet says: "After completion of the read operation from the current sector, the Sector Number is incremented by one and the data from the next sector is read and output on the data bus. This continued read function is called a Multi-Sector Read Operation. The Read Data command may be terminated by the receipt of a Terminal Count signal. ..." Write Data has a similar statement. There is no mention whatever of the EOT parameter. The use of TC is the only means described under the READ DATA and WRITE DATA commands to terminate the transfer. There only mention of EOT is a definition in a different section, which reads: "EOT stands for the final Sector number on a Cylinder. During Read or Write operation FDC will stop data transfer after a sector is equal to EOT". I interpreted this as "this should always have the highest sector number on the cylinder" and was used only to guarantee that multi-sector reads stop at the end of the track (which I thought would be an error condition). So I tried what the docs indicated, hit TC and it worked. When I did the 765 drivers in ImageDisk, they use DMA, and TC is generated automaticlly by the DMA controller - I remember thinking "ah .. how nice - this is how they really intended the system to work" - It always bothered me that I needed an extra select to use it in polled mode. Thanks - this cleans up another little bit of the picture. Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.parse.com/~ddunfield/museum/index.html