> So far as near as I can tell the earliest FDDs (IBM 23FD Minnow and Memorex > 650/651) used Step In/Step Out. The IBM 33FD Igar used direct control of the > motor. Someone asked (you?) on one of my Youtube videos for more detail about the 23FD's stepping method, so I made a video covering the finer details. https://youtu.be/AMPlJ7JayB4 -- Will