WHITCOMB%KOBOT@VENUS.YCC.YALE.EDU ("whitcomb%kobot.decnet@venus.ycc.yale.edu") (07/27/89)
Greetings:
We have been using Transputers for several years in robotics applications
which demand electrical isolation between Transputer nodes. Two
inexpensive and simple approaches have worked well for us:
The links on a Transputer eurocard, called the XP/DCS, which we have
developed are switchable to either INMOS TTL standard, as per evaluation
boards, or fiber optic. We use the Hewlett Packard "Versatile Link" HFBR-0501
modular series of components and cables. Each link is a two-fiber cable with
a plastic termination connector which plugs into a board mounted trans/rec
component. Note 5 Meg bandwidth limit.
We have also developed a trensputer-less eurocard, called the COM/MOD,
which performs TTL<-->RS-422 conversion for four standard INMOS links and
system services. See disgram below:
ANY TRANSPUTER <--> COM/MOD <-------------> COM/MOD <--> ANY TRANSPUTER
^TTL ^RS422 ^TTL
This allows us to hook up any standard transputer links over distances
of 10 meters at 20 Megahertz speeds, as well as system services. The
COM/MOD board also has activity lights on all wires, which can be nice.
For the non-hardware types in the audience: TTL is good for high speed
communication (such as links) only for short distances, typically on the
same backplane. When you hook two different, and possibly distant,
computers together other means must be used. I won't bore you with the
details, but the fiber-optic and RS-422 schemes mentioned overcome these
limitations.
We are interested in sharing what we have learned. I'll send some of our
papers to anyone interested.
The Best,
Louis Whitcomb,
ARPA: whitcomb%kobot.decnet@venus.ycc.yale.edu