Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!seismo!gatech!hao!ames!ucbcad!ucbvax!ICST-CMR.ARPA!rbj
From: rbj@ICST-CMR.ARPA (Root Boy Jim)
Newsgroups: comp.emacs
Subject: Re: 9600 baud problems (was Re: when using termcap, get it right!)
Message-ID: <8707231608.AA26532@icst-cmr.arpa.ARPA>
Date: Thu, 23-Jul-87 12:08:33 EDT
Article-I.D.: icst-cmr.8707231608.AA26532
Posted: Thu Jul 23 12:08:33 1987
Date-Received: Sat, 25-Jul-87 07:36:10 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 57

? A quick summary of RS-232C

And a good one at that. Now allow me to dream a bit...

First, I believe that all pieces of equipment should have female plugs
and that all cables should have male plugs. The rationale is that if the
pins break, you can replace the cable easier than the equipment.

Second, I would like to see a universal reversible plug. The thing would
have an odd number of pins. Ground would be in the center, all the
control (outbound) pins would be on the left side, and all the status
(inbound) pins would be on the right side. Actually, they wouldn't be
pins (because then there would have to be holes), but nore like overlapping
fingers. To make a null modem cable, one would mere put a half twist
in the cable before connecting it. The cable might look like:

		-------------------------------------
	GREEN	| TD RTS DTR XON GND XIN DSR CTS RD |	RED
		-------------------------------------

The connectors and jacks would be colored (or marked) on each side
so that even an idiot could connect them correctly.

Several problems remain. First, I may have to give up a universal
connector, as topology may not support reversibility. The latter
is more important.

Second, I left out RI and CD. What are their corrresponding signals
(or rather, what would they be if they existed)? Are they really
necessary for full duplex?

The two extra signals XON and XIN are for flow control. The former
I don't know how one modem would tell another modem to assert it's
XON when it sees XIN, but that's a hardware detail. They may not
even be necessary if RTS and CTS were handled this way.

Lastly, it'll never get done. All we need is another standard. Right!

? Note, that RS-232C has NO FLOW CONTROL.  Let me say this again.  THERE IS NO
? FLOW CONTROL.  RS-232C describes the interconnection of a terminal with a
? modem.  Some signals like TRANSMIT and RECEIVE DATA are passed through to the
? other side.  Other signals may be affected by actions on the other side, but
? they are indications from the modem to the terminal specifically.  RTS and
? CTS are properties of the transmission of DATA to the MODEM, these signals
? go no farther than the modem.  The same for DTR, DSR, CD, and RI.  If you
? are using RS-232, flow control needs to be done in the data stream.

Of course, if you use a null modem cable, you can do hardware flow control.
And of course, you can also use the wrong signals as we already know.
 
? -Ron
? 

	(Root Boy) Jim Cottrell	
	National Bureau of Standards
	Flamer's Hotline: (301) 975-5688
..  are the STEWED PRUNES still in the HAIR DRYER?