Oh. How about
those assorted daisy-chain schemes using RT11 phone cabl=
es?
I remember the labels reading something like
"much less expensive than
Ethernet".
I don't remember running into those, how were they interfaced? And used=
with=20
what sort of equipment?
Thypicallyt they were used with IBM-compatible PCs and plugged into the
serial ports. There were many schemes, but the simplest was something
like :
TxD o---->|--------+----------------o Network line
|
RxD o--------------+
|
DTR o-/\/\/--------+
SG o-------------------------------o Network ground/common
Some of the better versions had swiches built into the network cale
connector so that the resistor was only connected on the 'end' 2 machines.
The PC ran special software (oviously). THe DTR line was set -ve, and the
resistor pulled the DTR line (of all PCs on the network) to -12V. Any
machine could send data onto the network wire, all machines would then
receive it. The transmitting machine monitored its own transmission, if
there was a collision, it didn't see what it expected to see, there was
then a stnadarrd-tupe of collision recovery.
-tony