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From: peter@graffiti.UUCP (Peter da Silva)
Newsgroups: net.dcom,net.periphs
Subject: Re: Definition of "null modem" cable
Message-ID: <158@graffiti.UUCP>
Date: Tue, 3-Sep-85 07:14:28 EDT
Article-I.D.: graffiti.158
Posted: Tue Sep  3 07:14:28 1985
Date-Received: Tue, 10-Sep-85 03:36:13 EDT
References: <195@almsa-1> <340@ecsvax.UUCP>
Distribution: net
Organization: The Power Elite, Houston, TX
Lines: 29
Xref: watmath net.dcom:1270 net.periphs:843

Here is the minimum null-modem cable I have ever used. Note that it's really
not suitable for anything but a hardwired terminal, short haul, but it's
perfectly good for connecting DEC terminals to non-DEC computers & vv.

		 2------------3
		 3------------2
		 4-+        +-5
		 5-+        +-4
		 7------------7
		 6-+        +-6
		 8-+        +-8
		20-+        +-20

Conscientious hackers will want to connect 1, 4 and 5:

		 1------------1
		 2------------3
		 3------------2
		 4------------5
		 5------------4
		 7------------7
		 6-+        +-6
		 8-+        +-8
		20-+        +-20

But for most cases 6, 8, and 20 are irrelevant. Of course if for some weird
fetishistic reason you want to look like a real pair of modems, leave 4 and 5
dangling & do something useful with 6, 8, and 20. The 3-wire cable at the top
will handle a good percentage of your cabling needs.