20 Jan
2014
20 Jan
'14
4:27 p.m.
On 20/01/2014 22:35, Richard wrote:
In article <52DD8D23.8090908 at bitsavers.org>,
Al Kossow <aek at bitsavers.org> writes:
Do you mean not RS-232 ASYNC. Sync interfaces, including SDLC and HDLC
are still RS-232...
On 1/20/14 12:06 PM, Richard wrote:
Yeah, once you get into the weird
polling schemes and "multiple
terminals hanging off a single modem" daisy-chain craziness, then
you're really getting into weird territory.
A lot of that stuff was "proprietary"
but I suspect that it was just
some variant (possibly minor enough so as not to be distinguishable on
operating equipment) of an IBM synchronous serial communication
scheme.
Univac, Burroughs and HP all had their own variants of polled block mode
terminals through synchronous comms lines. If it has a BNC coax
connector out the back, it's most likely talking 3270.
My airline terminal has
something that looks like an RS-232 port, but
it's not RS-232. It appears to be some sort of synchronous variant of
SNA in terms of signals:
<http://user.xmission.com/~legalize/vintage/images/westinghouse/W1643-2.jpg>