Subject: SCSI Connector Pin Outs
From: [email-masked] (Paul H Bauer)
Date: 20 Jul 1994 12:43:36 GMT
Newsgroups: comp.sys.apple2

This should probably find its way into the FAQ but hopefully it will
be of help to those people having problems with Hard drives "dissappearing"
when one or more devices are disconnected from their SCSI chain. Remember
that Apple Cards generally do not provide SCSI terminator power so one or 
more devices on the chain must provide this power to see anything on the
chain.

	Here are the pin-outs for the various connectors:

 
SCSI pinouts:
 
25 pin    ident          50 ide         50 SCSI RIBBON      GODrive
 
1         REQ            48             49                  36
2         MSG            42             46                  30
3         I/O            50             50                  33
4         RST            40             45                  29
5         ACK            38             44                  28
6         BSY            36             43                  26
7         GND            37             19
8         DB0            2              26                  6
9         GND            39             20
10        DB3            8              29                  12
11        DB5            12             31                  16
12        DB6            14             32                  18
13        DB7            16             33                  20
14        GND            1,3,5          1,2,3
15        C/D            46             48                  34
16        GND            7,9,11         4,5,6
17        ATN            32             41                  25
18        GND            13,15,17       7,8,9
19        SEL            44             47                  32
20        DBP            18             34                  22
21        DB1            4              27                  8
22        DB2            6              28                  10
23        DB4            10             30                  14
24        GND            45,47,49       23,24,25
25        TPWR           26             38                  24

 
 
                         IDE 50 pin connector "into drive"
 
2  4  6  8  10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
1  3  5  7  9  11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

 
                         50 PIN SCSI Ribbon connector
 
  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
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[email-masked]