Wiring terminals 300 ft. from the computer

[John Watson]

In article <11774 at bsu-cs.bsu.edu>, jennifer at bsu-cs.bsu.edu (Jennifer Freeman) writes:
> locate the computer about 300 feet away from where the bulk (10-14)
> of the terminals will be.
> What type of wiring would be needed for this?  Would shielded be
> good enough?  Would some kind of line boosters be needed?  We have some people

The computone cluster controller lets me (one of my customers) use one
board in their 486 running Xenix 2.3.2, which connects to 4 cluster boxes.
The boxes are several hundred feed away, check specks.  Each box supports
16 terminals/printers.  I have not tried modems on these boxes, net users
have reported various modem/computone problems.  The "trunk" cable is custom,
you buy it from them.  It has 3 pair shielded, using a protocal similar
to RS422, balanced low impedance etc...

If you try it with just long wires, the shielded wire tends to have high
capacity/foot and may be a problem.   Also long wires tend to pick up
lightning charges like antenna, so have a pocked full of 7518[89] chips
handy.  The small guage "cheap" telephone wire tends to have a higher
characteristic impedance and work better on the rs232 interface.  Chose
your pairs well, don't pair tx/rx for instance.

Good luck, its a jungle.  No matter what you do, someone will second guess
you when that board breaks or lightning gets your terminal.  I have read
on the net that others have had good look with ARNET boards. 

Just trying to help, no ax to grind, not trying to make a buck.
          John Watson   Middlesex NJ USA