Anyone know where the Step/Direction version of the FDD interface originated.
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. The earliest Step/Direction FDD I can find is the Shugart 800 which first shipped in September 1973. Tom