[kwlug-disc] Advanced(?) Git usage question

Bob Jonkman bjonkman at sobac.com
Sat Apr 19 23:25:44 EDT 2014


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The PACX and Starmaster were connected to the terminals and host using
a Gandalf-supplied converter on the serial port. The converter enabled
synchronous full duplex at 9600bps on four wires which we ran through
a BIX patch panel.  We used to plug an earphone into the panel to
listen for the modulation tone to trace a circuit. I think the
converter may have used RS-422, but it's possible it was a proprietary
signalling scheme.

The PACX had DOV cards, Data Over Voice, which connected buildings in
three different cities.  This gave us the weird situation of having a
terminal's digital signal going out an analog modem connected to a
PACX which digitized it to the DOV to provide an analogue signal to
the Bell switch which digitized it to send it to its destination,
where it would undergo another digital to analogue to digital to
analogue to digital conversion to connect to the host.

- --Bob, who thinks maybe the thread subject has meandered somewhat.


On 14-04-19 05:15 PM, John Johnson wrote:
> On 2014-04-19 15:47, Bob Jonkman wrote:
>> Gandalf made "terminal routers" or trouters.  I administered
>> several PACX (Private Automated Computer eXchange) devices, which
>> were later upgraded to the Gandalf Starmaster device.
> The Gandalf PACX equipment came along many years after coax bus / 
> multiplexer I mentioned earlier. My employer in 1980s also designed
> and sold data switching equipment, based on a telephone PBX.
> 
> In the PBX Voice was digitized, into PCM, and circuit switching was
> done in the digital domain.
> 
> The company thought decided to extend the existing digital circuit 
> switching capabilities of the PBX with the addition of digital
> line cards supporting a number if circuits for asynchronous serial
> data communications at speeds in the range of 9600 bps (common in
> the 1980s).
> 
> It is common, but incorrect, to equate RS232 with asynchronous,
> serial data communications. RS232 can be used for synchronous,
> serial data communications as well.
> 
> IIRC: The X.25 PAD equipment connected with the network through
> 4800 bps modems that were RS232 synchronous on the digital side and
> connected to a conditioned leased line in the analogue side.
> 
> JohnJ
> 
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