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From: raymond@math.berkeley.edu (Raymond Chen)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: null modem cable
Message-ID: <1991Jan19.195327.18876@agate.berkeley.edu>
Date: 19 Jan 91 19:53:27 GMT
References: <2582@s5.Morgan.COM>
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Reply-To: raymond@math.berkeley.edu (Raymond Chen)
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In-Reply-To: joec@Morgan.COM (Joe Collins)

In article <2582@s5.Morgan.COM>, joec@Morgan (Joe Collins) writes:
>Anyone know how to make an null modem cable ...

The pinout for a null modem cable is given in the "comm" file in
my comp.sys.ibm.pc.misc archives (ftp math.princeton.edu:pub/rjc/csip).
Here is the relevant excerpt:

[@(#)comm	1.3.  Last updated 3/23/90]

SERIAL PORTS AND THINGS

To hook up a null modem
      1  2  3  4  5  6 20  7
      |  |  |  |  |  |  |  |
      1  3  2  5  4 20  6  7

    In some cases you may have to tie 6 & 8 on the same end together as well.

The "comm" file also contains assorted comments on how to get COM3 and COM4
set up, how to program the serial port, and what sort of UUCP packages
exist for the IBM PC.