Hi, I just built myself a 68-pin BPPC scsi cable - thought I'd note down the details for anyone else who want one.
At the far end I have a 68-pin terminator block providing high- and low-byte termination.
On the position nearest the PPC I have a 68- to 50-pin connector block which provides high-byte termination and the BPPC itself provides the low-byte termination.
On the 50-pin connector I have a cdrw
In between the cdrw and the terminator at the far end I now have 5 x 68-pin connectors avaiable for hard-drives - of course they only operate in narrow mode, but because both high- and low-bytes are terminated at each end there are no problems.
Confusingly the pinout convention changed between 50-pin and 68-pin cabling, so that on the 50-pin cable the wires are numbered 1, 2, 3, ... 50
On the 68-pin cable the wires are numbered 1, 35, 2, 36, 3, 37 .... 33, 67, 34, 68.
However this is ignored in the following description, and I just describe the ribbon.
In terms of attaching the high-density 68-pin cable to the high-density 50-pin connector for the PPC the pitch of the wires is identical, which makes things very easy.
Starting from the red cable:
With reference to
this schematic:
Cut back the first 10 wires - you do not need them:
The next 22 wires are connected to pins 1-22 of the BPPC 50-pin HD connector.
Cut back the next 2 wires - you do not need them.
Connect the next 2 wires to pins 25 and 26 of the BPPC connector (you leave 2 pins unconnected).
Cut back the next 2 wires - you do not need them.
Connect the next 22 wires to pins 29-50 of the BPPC connector block (again 2 pins are disconnected).
Quite simple to connect once the correct wires have been removed form the ribbon.
A picture of the final cable is posted
here.
Regards
Rich
