rts/cts - a tutorial on flow control

[cyrus]

Now I like this discussion...it has some meat to it...

> when they first started. Their 3101 terminal has a female 25 pin connector,
> which is wrong. But they learn from their mistakes and listen to their
> customers. The IBM-PC and the 7171 are both DTE and have male connectors,
> just like they're supposed to. The 7171 understands the Ring signal,

Why is a female connector on a DTE terminal port wrong???
As far as ASYNC-only devices go, a male DTE connector is quite rare.
For multiplexers with SYNC composite channels, most are male in order
to avoid customer confusion in differentiating the host connectors from
the modem connector.  In any case the vendor should supply a cable with
the proper gender at each end to help the customer.

> Data Terminal Ready, Clear To Send, Data Set Ready, Data Carrier Detect,
> and Request To Send. How many pieces of equipment do you know that look
> at or do anything meaningful with DSR?

Most SYNC devices will refuse to communicate without DSR asserted.

> Argh. I cring at the idea of using DTR for flow control. I am sure people
> will say, printers do it all the time, or "it works for me". I still cring.
> I'd like you to try doing it through a 212 modem some time.

Personally, I cringe at the thought of using half-dux transmission
(RTS, CTS, and DCD all toggling at just the right moments) over a full-dux
line...All that wasted bandwidth!!!

>  What do you do the day after a peak experience?

Take a shower...:-).

			-Cyrus Azar (313) 995-1555 || ihnp4!umich!symplex!cyrus

			Symplex Communications
			5 Research Drive
			Ann Arbor, MI  48103

"The opinions expressed here are nothing more than the random effects of
a slew-rate limited 1488 being fed by a rather noisy switching power supply"