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.