SCSI DECstation 2100/3100 to Centronics type SCSI

The DEC connector has 68 pins in two rows of 34. Distance between the rows is probably 0.1", distance between adjacent contacts in a row is probably 0.05". The connector on the cable is female. There is a trapezoid shell around the contacts that extends about 0.2". This is probably an AMP type 174731-5 connector.

View on cable end of connector (NOT on contact end):

______________________________________
\ .................................. /
 \................................../
  __________________________________
(arbitrary) contactnumbering:
  1................................34
 35................................68

The Centronics type connector has a similar shape, but is much bigger. This connector resembles the "CHAMP" connector system in the AMP catalogue. It has 50 contacts in two rows of 25. The connector on the cable is male.

View on the cable side of the connector:

_____________________________
\ ......................... /
 \........................./
  _________________________
(arbitrary) contactnumbering:
  1                       25
 26                       50

The connections

DECstation CHAMP          DECstation CHAMP
    1 NC                     35 NC
    2 NC                     36 NC
    3 NC                     37       37
    4 NC                     38 NC
    5        1               39 NC
    6       38               40 NC
    7       26               41 NC
    8       27               42 NC
    9       28               43        6
   10       29               44 NC
   11       30               45 NC
   12       31               46 NC
   13        7               47        2
   14       32               48 NC
   15       33               49 NC
   16       35               50 NC
   17       42               51 NC
   18       17               52 NC
   19       43               53 NC
   20       18               54 NC
   21       44               55        4
   22       19               56 NC
   23       45               57        5
   24       20               58 NC
   25       46               59 NC
   26       21               60 NC
   27       47               61        3
   28       22               62 NC
   29       48               63        8
   30       23               64 NC
   31       49               65 NC
   32       24               66 NC
   33       50               67       10
   34       25               68 NC
As a check the same cable seen from the other side:
   CHAMP DECstation          CHAMP DECstation
    1        5               26        7
    2       47               27        8
    3       61               28        9
    4       55               29       10
    5       57               30       11
    6       43               31       12
    7       13               32       14
    8       63               33       15
    9 NC                     34 NC
   10       67               35       16
   11 NC                     36 NC
   12 NC                     37       37
   13 NC                     38        6
   14 NC                     39 NC
   15 NC                     40 NC
   16 NC                     41 NC
   17       18               42       17
   18       20               43       19
   19       22               44       21
   20       24               45       23
   21       26               46       25
   22       28               47       27
   23       30               48       29
   24       32               49       31
   25       34               50       33
Use a cable with shielding (connected to the metal trapezoid shield of the connectors).