Pin #   Name        Note
     -----   ----        ----
     1       rdy-        i/o     id and ready
     2       dkrd-       i       mfm input
     3       GRND        G       -
     4       GRND        G       -
     5       GRND        G       -
     6       GRND        G       -
     7       GRND        G       -
     8       mtrxd-      o       motor control.
     9       sel2b-      o*      select drive 2
     10      dresb-      o       reset
     11      chng-       i/o     disk changed
     12      +5v         PWR     540 mA average 870 mA surge
     13      sideb-      o       side 1 if low
     14      wpro-       i/o     write protect
     15      tk0-        i/o     track 0
     16      dkweb-      o       write gate
     17      dkwdb-      o       write data
     18      stepb-      o       step
     19      dirb        o       direction (high is out)
     20      sel3b-      o*      select drive 3
     21      sel1b-      o*      select drive 1
     22      index-      i/o     index
     23      +12v        PWR     120 mA average 370 mA surge


   Key to Class:

        G       ground, note connector shield grounded.
        I       input pulled up to 5v by 1K ohm.
        I/O     input in driver, but bidirectional input (1k pullup)
        O       output pulled though 1K to 5v
        O*      output, separates resources.
        PWR     available for external use, but currently used up by
                external drive.