The setting is "Cylinders" in the main settings menu, and it indicates the maximum number of cylinders that IMD will attempt to read from the disk (when writing IMD uses the cylinders occuring in the image - unless you use the track exclusion feature to avoid writing certain ones). IMD uses "Cylinder" to refer to the actual cylinders - ie: actual steps of the head(s) - it uses the "Singe/Double sided" setting to determine how many tracks occur in each cylinder ("as read" means it will try to read both sides for the first few tracks to determine. In IMD 0 is a special case, but it means to quickly scan the disk getting what it can on one read and NOT to re-analyze the disk if it cannot read data from a track - in doing so it also prevents the automatic stop when data runs out ... it's just a quick way to scan the whole disk to check a particular format. Agreed is it not recommended as a way to get reliable disks. They also use different sector numbers on side 1 - in fact, they logically number both sides as if it were a single side (head 0) with ascending sector numbers through the sectors on both sides. IMD simply records the cylinder, head and sector numbers found in the sector headers of any given physical track and recreates them as it writes the disk - it does not expect them to contain any particular value, so it reads/writes kaypro disks with no problems. Dave -- dave13 (at) Dave Dunfield dunfield System/Firmware development services: www.dunfield.com (dot) com Classic computers: http://www.classiccmp.org/dunfield