EXTERNAL DISK ...DB23 FEMALE
----------------------------

For A1000, A500, A2000 and A3000 with A2000 and A3000 differences noted.

1   rdy*                             13  sideb* 
2   dkrd*                            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/a3000 not used (1))
9   sel2b* (a2000/a3000 sel3b* (1))  21  sel1b* (a2000/a3000 sel2b* (1))
10  dresb*                           22  index* 
11  chng*                            23  +12 
12  +5 

(1)  sel1b*  is not drive 1, but rather the first external drive.  not
    all select lines may be implemented.