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25094FD 1771 - Floppy Drive Controller ERRATA???

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  • joshbensadon
    Apr 6, 2012
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      I've been struggling with this Tarbell 1011 controller using the FD 1771 controller for a couple of weeks.

      I kept getting FF's out while I was watching good data go in.
      The only time I got any other data, was when the (external) Clock/Data seperator swapped the clock & data.

      I looked everywhere for the problem. I even made my own Clock/Data test pattern generator to give clean pulses. Once again, only when I reverse Clock and Data does it seem to work.

      So, I swaped the Clock and Data. Curiously, the circuit now works!

      The first ID field looks like this...
      FE 00 00 01 00 D2 C3

      I am assuming the CRC (D2C3) is correct.

      Does anyone have any ERRATA on the FD 1771 Floppy Drive controller?

      I am curious if anyone else out there has any schematics or circuits using the FD 1771 with external data seperator and would you confirm Pin 27 for Data, Pin 26 for Clock (as per data sheet) or are these truely reversed?

      PS. Thank you to everyone for all the help, support and invaluable idea's given. And sorry for the mess of hair on the floor :)
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