In article <5.0.0.25.2.20060318002454.02be3538 at pop.east.cox.net>,
"John K." <john3000 at cox.net> writes:
Going way beyond the "Party Line" topic,
does anyone remember the Sytek
system? The Sytek network used bidirectional CATV technology for the
backbone and network interfaces that used two Z80 processors to connect
RS-232 devices. One Z80 handled the RS-232 interfaces (you could have 1 to
8 19,200 bps RS-232 ports) and the other handled the
modulation/demodulation of the RF carrier. A 68000 Unix box acted as the
network control center (NCC). When you turned on a terminal and hit return
you got the attention of the NCC and it gave you a menu of available
devices (ones which you had permission to access ANDed with the devices
[systems] which had available ports). I know the Sytek system was used at
NASA, as it was through NASA that we found out about the Sytek "local area
network" equipment sometime about 1979 or 1980. With the CATV bandwidth
and the frequency spectrum divided up for various uses, the Sytek network
allowed a dozen or so video channels, a few thousand phone calls, and
several thousand 19.2 kbps terminal connections simultaneously on a single
cable. Not bad for late 1970's technology.
UDel had something similar at the same time, although it was locally
referred to as the "port selector". I have a feeling it was a PDP-11
or other minicomputer locally configured with software to do the
connection. Local serial terminals would connect to a remote machine
by pressing <RETURN>digit<RETURN>, so <CR>4<CR> connected you to
a
PDP-11/70 running RSTS/E while <CR>3<CR> connected you to the Burroughs
B6700, etc. I remember at least the following machines being
connected:
- PDP-11/70 running unix
- PDP-11/70 running RSTS/E
- DECsystem-10 running TOPS-10
- B6700 running whatever ran on the Burroughs :-)
- HP3000 with BASIC front end
I think there may have been one or two other machines that I never
used. The machines themselves were located in a secure computing
center building across town, so there was some sort of network between
the terminal building and the computer center.
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