STONE@SUMEX-AIM.STANFORD.EDU (02/07/87)
I would like to better understand the tradeoffs in connecting asynchronous
terminals to a large UNIX host. Specifically, in the case where a group of 5
to 10 terminals are located in the same building but not close to the host, I
see the following possibilities:
- pull RS-232 cables, one per terminal; I believe that the problems
of this approach are that
* it may be expensive to pull a bunch of RS-232 cables to a
far corner of a building
* it may just not be feasible to pull such a bundle
- go to 4-wire cabling giving up certain RS-232 signals which I
believe are not always necessary; then use (previously installed)
4-wire telephone cabling to go to the far reaches and then come
back to an RS-232 connector at each terminal
- use a multiplexor at both the host and terminal ends with a
single cable between
- connect via LAN using a terminal concentrator on the terminal
side and then either another deconcentrator (going to RS-232
which plug into a host board) at the host, or directly into the
host via LAN board and appropriate host software to "decon-
centrate"
- if the hosts supports direct PBX connection, then using telephone
cabling from terminals to PBX and PBX link between PBX and
host may work
Can anyone help me understand the pros and cons of the approaches? Are
there other approaches to consider? I am primarily interested in the trade-
offs between direct RS-232 connection, multiplexors, and LAN connection.
What are the general prices of the various solutions?
Why would one ever want the multiplexor solution?
Thanks,
Jeffrey Stone
Menlo Park, CA
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