Hi I'm using one of the TRS80's controller for my M20 Olivetti.It is also, exactly the same as the WD1000 except that annoyingwrite protect signaland data buffers. As was mentioned, the write protect is not part of theoriginal spec.I had to hard tie the wire to get the controller to work witha ST251.My Olivetti did expect bad track information on the first track and sector.The disk I had was used on a PC and had other information in thatlocation. I had to write some code to erase that bad track part beforeI could get the disk to initialize.I also had problems because of the stepping rate of the ST251 was slowerthan the original Olivetti. I had to find the code on the Olivetti floppy disk( not in the bios, it needed to boot from floppy first ) and change the timingto use the auto stepping.Dwight