Pin  Description              Pin  Description
 1   RDY*                     13   SIDEB*
 2   DKRDY*                   14   WPRO*
 3   GND                      15   TK0*
 4   GND                      16   DKWEB*
 5   GND                      17   DKWDB*
 6   GND                      18   STEPB*
 7   GND                      19   DIRB
 8   MTRXD*                   20   SEL3B*  A2000 not used (1)
 9   SEL2B A2000 SEL3B* (1)   21   SEL1B*  A2000 SEL2B* (1)
10   DRESB*                   22   INDEX*
11   CHNG*                    23   +12V
12   +5V
(1) SEL1B* is not drive 1, but rather the first external drive. Not all
    select lines may be implemented.

Internal Disk Drive Header

Pin  Description              Pin  Description
 1   GND                      18   DIRB
 2   CHNG*                    19   GND
 3   GND                      20   STEPB*
 4   MTR0D* (led)             21   GND
 5   GND                      22   DKWDB*
 6   N.C.                     23   GND
 7   GND                      24   DKWEB*
 8   INDEX*                   25   GND
 9   GND                      26   TK0*
10   SEL0B*                   27   GND
11   GND                      28   WPRO*
12   N.C.                     29   GND
13   GND                      30   DKRD*
14   N.C.                     31   GND
15   GND                      32   SIDEB*
16   MTR0D*                   33   GND
17   GND                      34   RDY*