If you take the time to read/understand the IMD docs and/or help screens, you will note that I explicitly state that IMD does not make ANY assumptions about your drive. It simply uses the capabilities of the controller to see what it can find "out there". The point of note here is that it supports up to the theoretical maximum of 255 cylinders that the 765 controller architecturally supports. So why would it assume that your drive cannot have more than 80 physical cylinders. It has no idea what type of drive you have. Sure, drives with more than 80 cylinders aren't common, but sometimes extra data is hidden in an extra track beyond the end... Some times two tracks ... why may any such assumptions - At one time 8" drives with 77 cylinders were "as big as it gets" - so NEC designed a 77 step limit into the original 765 ... which means they fail on long seeks on more modern 80 cylinder drives - requiring software workarounds ... IMD makes no assumptions about the drive - it simply does what you ask it to do. When you set double-stepping, you are simply telling IMD to send two step pulses for each cylinder it wants to move the head. It will try to read the number of cylinders that you specify. It does not "guess" that your drive may not be big enough to contain those cylinders because of other settings that you have made. IMD is about doing what you ask it to do, not trying to "fix it up for you". If you want to read a 40-cylinder disk --- set it to read 40 cylinders. It defaults to 80 cylinders because that will read most comon disk types without the user having to actually know what he is doing. Most drives will allow seek a couple of tracks past the certified number of tracks. In *MOST* disks, these "extra" tracks will not contain any data. At it's default settings, IMD will stop when it encounters a track with no discernable data - in *most* cases, this signifies the end of data tracks on the disk. So if you read a 40 cylinder disk while set to read 80, it will read 0-39 and stop on track 40. But this is because it "ran out of tracks" when it hit the extra track (40 = track# 41). But... if the disk contains data in this area, IMD will happy continue reading up until it either runs out of data, or hits the specified cylinder limit. This is why some of my Kay disks have the extra SD track 40 -- the original disks actually have this track one step beyond the certified limit of the drive. It also means that if your drive does not step past the certified limit, or you have data in all of the "extra" tracks before it hits the stop, then it will continue to step, banging the head against the stop until it gets to the number of cylinders you specified (because it never runs out of tracks with data). I designed IMD to be a fairly powerful tool, and not to limit you by making assumptions about what you are doing - as a result, you have to know more details about what you are doing than "other" disk archival utilities ... I do provide a lot of useful information in my docs and help files to help you get it sorted out, but it does require an inventment in time/effort to get there. Which leads to the question ... if you have TeleDisk images for the disks you want to create, and are finding IMD unsuitable - why not use Teledisk to recreate the disks. TeleDisk is designed to "make it easy" - it looks at the BIOS settings to see what kind of drive it is, and makes decisions based on that - for basic operations, it will be simpler than IMD to use. Dave -- dave13 (at) Dave Dunfield dunfield System/Firmware development services: www.dunfield.com (dot) com Classic computers: http://www.classiccmp.org/dunfield