Modular jack serial lines on 3B2

[andrew.d.hay]

In article <132 at bongo.UUCP> julian at bongo.UUCP (Julian Macassey) writes:
"In article <12 at lysator.liu.se>, aronsson at lysator.liu.se (Lars Aronsson) writes:
"> 
"> I was planning on going modular for my RS232 serial lines and was
"> looking for standard, but there seems to be none.
[]
"	A gotcha. Some line cords will rotate from one plug end to the other. 
"Pin 1 will go to 8 and 7 to 2 etc.

there is a sort of de facto standard for the rj45 (8-pin mod)
connector, but for some odd reason at&t reversed it for the sockets on
the 3b2...  if you want to connect a 3b2 to *anything*, you need a
'half-twist' cable.  rs232 to rj45 adaptors generally (always, in my
experience) follow the standard; equipment such as the at&t data
switch ('datakit') also do.
why the arrangement of signals is as it is instead of something
rational like
	gnd
	dsr
	rts
	txd
	rxd
	cts
	dtr
	gnd
i don't know.  they could have made the question of null modems moot.

-- 
Andrew Hay		+------------------------------------------------------+
Ragged Individualist	|	 But I thought we were *ALL* iconoclasts!      |
AT&T-BL Ward Hill MA	|		I was just trying to fit in!!!	       |
a.d.hay at att.com		+------------------------------------------------------+