IBM 3101 Dip Switches Configuration

From: Jay West <>
Date: Thu Jan 24 17:55:16 2002

> > The cable used is one
> > normal serial cable.

There is absolutely no such thing as a "normal" serial cable. System
designers and engineers always seemed to play foot loose and fancy free with
RS-232, determining which signals to implement, etc. Even with a "complete"
implementation, you still have the issue of DTE-DCE or DT/CE to DT/CE, etc.

I guess the closest one could come to defining a "normal" serial cable is
all 25 signals, wired "straight through". This cable only typically works
with DTE to DCE connections, or most commonly, a terminal to a modem. I
would say this approaches "normal", only because RS-232 was designed for
going from a DTE to a DCE, and anything else - was "home brew". I have seen
some awfully creative ways to defeat the DTE to DCE design when hooking up
devices of the same type. Forcing signals high from the test voltage pins,
etc. RS-232 is such a mongrel.

Jay West
Received on Thu Jan 24 2002 - 17:55:16 GMT

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