"Will Jennings" <xds_sigma7(a)hotmail.com> wrote: Hi Will There was nothing special about the SA900's that made them usable for hard sectored. It is just the controller that cares about counting index pulses ( I have a Nicolet 1080 ). The SA900 and the SA800-1 were that same except that the connector on the 800's are 50 pin and the 900's were 44 pin. The issue is that the 900 always had a clock separator. Not all 800's have them. Note to Don: It seems like I remember when trying to figure out what kind of disk I needed, that there was also a 10 sectored 8 inch as well as the 32. The only way to tell what kind of controller one has is to follow the index signal into the controller and trace out the circuit. If you find some one shots that have time constants and gating that looks like it would pick out the disk index from the sector holes, then you have hard sectored. As far as formatting, my machine needed a combination of setting up registers and some software to get it to work. This is not always true for all hard sectored setups. Some just require that you write to each sector so that there is clocking information. In my case, I needed to use 32 hard sectored disk that were combined into 2 sectors of 16 holes each. I also had to have a track number at the beginning of each track that was written in bit reversed order. Figuring this out kept me off the streets at night for a few weeks. Later Dwight