Need 3b1-end pinouts for parallel interface

[Ward Griffiths]

dlb5404 at tamuts.tamu.edu (Daryl Biberdorf) writes:

>I was going to hook up the old C.Itoh Prowriter 8510 this weekend
>when I noticed that my 3B1 uses a female centronics connector instead
>of the more common DB-25 for its parallel port.  After calling around,
>no local businesses stock the male centronics-male centronics cable I need
>and special ordering it looks like it will cost more than I think it should.
>:)  So I guess I'll make my own.

You can get the clamp-on Centronics connectors and the ribbon 
cable at any Radio Shack, and I believe that the Radio Shack 
Computer Centers stock an assembled "printer extension cable" 
that has the two correct connectors as well.  Remember, the 
"more common" DB-25 connector was not used for parallel ports 
untill the IBM PC came out, with a male instead of female 
serial connector (female makes a lot more sense to me -- if a 
pin breaks it's easier and cheaper to replace a cable than to 
repair the CPU) and a parallel connector that looked like 
everybody else's serial connectors.  In the early days, I saw 
several examples of hardware fried by folks thinking that it 
was a serial port.  Of course, nothing like the time someone 
plugged a Tandy Daisy Wheel Printer II (a machine I had thought 
impossible to break) into the female DB-25 connector that 
serves signal AND power to AT&T monitors in the back of an AT&T 
6300.  Smoke city for CPU and printer.

>Anyway, I have the pinouts for the printer (equivalent to the Apple
>Imagewriter I and the AT&T 470, I believe), but I don't have them
>for the computer.  Can anyone help?

Pin one to pin one, pin 36 to pin 36, and everything in between
follow suit.

>These pin numbers are for the standard 36-pin Centronics-style connector.
>Will I need a full 36-conductor cable to accomplish all these connections?
>(33 if I ignore the NC pins)  If so, how does a clone accomplish
>parallel communications with a DB-25 connector and still allow for
>communications TO the machine through that connector?

IBM did away with a number of redundant ground lines that were
in the 36-pin connectors.

-- 
          Ward Griffiths, Unisys NCG aka Convergent Technologies                The people that make Unisys' official opinions get paid more.  A LOT more.
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