>From my boss:
Here is my write-up on the cable. Please post to appropriate places, and
include a disclaimer saying that we're not resonsible if it's wrong and
they hose their equipment.
==============================================================================
I had a surplus Sun SCSI disk drive which I wanted to use with my PC. I
bought an Always Technology IN-2000 SCSI Adapter Card. The external connector
on this card is a DB-25 and the only SCSI cable I could find that had this on
one end was the standard Mac system cable, which had a 50-pin "Centronics" on
the other end. This didn't help since the disk drive I wanted to use had the
Sun SCSI-1 connector, the D-connector with three rows of pins, which I was
told is called DD-50.
We put out an appeal on the net, which yielded several suggestions. One was
to simply make a centronics-50 to DD-50 jumper using insulation displacement
connectors. This is what I had originally intended to do but the cost of the
DD-50 IDC was over $20, so I thought I'd order a cable with the desired
connection. We ran into problems because the pin numbering scheme on the IDC
and solder-type connectors are different from the Sun SCSI-1 convection.
The IDC connectors are numbered like so:
-----------------------------------
\ 01o 02o 03o ..... 17o /
\ /
\ 18o 19o ..... 33o /
\ /
\ 34o 35o 36o ..... 50o /
-------------------------
Sun SCSI-1 connectors are numbered like this:
-----------------------------------
\ 01o 04o 07o ..... 49o /
\ /
\ 03o 06o ..... 48o /
\ /
\ 02o 05o 08o ..... 50o /
-------------------------
The proper pin-outs for these connectors are as follows:
MAC/IBM SCSI-1 IDC
Signal DB-25 DD-50 50-Pin
------ ------- ------ ------
-DB(0) 8 2 34
-DB(1) 21 4 2
-DB(2) 22 6 19
-DB(3) 10 8 36
-DB(4) 23 10 4
-DB(5) 11 12 21
-DB(6) 12 14 38
-DB(7) 13 16 6
-DB(P) 20 18 23
-TERM PWR 25 26 42
-ATN 17 32 44
-BSY 6 36 29
-ACK 5 38 46
-RST 4 40 14
-MSG 2 42 31
-SEL 19 44 48
-C/D 15 46 16
-REQ 1 48 33
-I/O 3 50 50
all other pins not listed above are ground (GND).
This should allow you to use Sun SCSI-1 devices with a Mac or with a PC having
the Allways IN-2000 SCSI Adapter card in it.
However, after all this, we discovered that the controller card in the
drive was not standard scsi anyway, so we took the drive out and
connected it via esdi. Oh well.
-- Edward Hartnett ejh@khonshu.colorado.edu
This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:06:53 CDT