Need 3b1-end pinouts for parallel interface

[Dave Hanna]

In article <12356 at helios.TAMU.EDU> dlb5404 at tamuts.tamu.edu (Daryl Biberdorf) writes:
>In article <11489 at jpl-devvax.JPL.NASA.GOV> mark at jpl-devvax.JPL.NASA.GOV (Mark R. Rubin 4-7794) writes:
>>
>>	:: I have been using a C. Itoh 8510 with my PC7300 for over five
>>	   years. No problems. I use a standard, 36-pin, Amphenol,
>>	   male-both-ends, Centronics-style, cable
>
>The problem is that I don't want to buy a ready-made cable.  They're kind
>of pricey around here, and I don't want to have to drive to Houston
>or Dallas to pick one up at an acceptable price.  But before I make
>my own, I'd like to know exactly how many pins *need* to be hooked up
>and whether or not they're straight through (pin 1 on computer goes to
>pin 1 on printer, pin2 to pin 2, etc.).

If you're not _real_ concerned about RFI, (i.e., you don't live in
an apartment complex with 3 different neighbors TV sets within a
30 foot radius :^), you ought to be able to get a pair of ribbon cable
type connectors and a length of 36 conductor cable from someplace
like Radio Shack and make your own pretty easily.  The connectors will
probably set you back about $5 apiece, and maybe .50 a foot for the
cable.  If you have a vice to squeeze the connectors in, it shouldn't
take more than 10 minutes or so to make up the cable.

If your Radio Shack doesn't have the necessary parts, we have a place
up here in Dallas called Off the Shelf Components that stocks all sorts
of stuff.  I'm pretty sure they will do phone/mail order, and I don't
think they have a minimum.  I've dealt with them before, though on a
walk-in basis.  Phone number is (214) 247-0052.

>Anyway, this is in no way intended to be a flame.  I'll still appreciate
>any help anyone can give as far as whether or not I can wire a cable
>straight through and exactly which connections need to be made (fewer
>conductors means less cost for my cable).

The actual wires are a small part of the cost - most of it is the connectors.
If you use ribbon cable as I suggested, the difference between, say 10 feet
of 36 conductor and 10 feet of 25 conductor isn't going to be that much.
I'm usually much more concerned with being able to get it done easily and
quickly than with saving a dollar or two.

Anyway, if you really insist, I think you'll find that the DB-25 solutions
drop some of the extra ground wires.   The standard pinout, when run
through a ribbon cable, gives you a ground wire between each data wire,
which provides both noise suppression and cross-talk immunity.  But data
going to a printer is not that fast that noise needs to be too much of
a concern.  If you wanted to connect those ground pins together at the
connectors and just run 1 or 2 ground lines through the cable, you probably
wouldn't get in any trouble.
>
>--Daryl Biberdorf,  dlb5404@{rigel,tamuts}.tamu.edu
>  Texas A&M University


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Dave Hanna,  Infotouch Systems, Inc. |  "Do or do not -- There is no try"
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