ADRIAN@vax.oxford.ac.uk (04/29/89)
Re: "Parallel output on TDS2 for the PC - Kenneth Lui"
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On the TDS, the screen is an occam channel. An occam channel is a point-to-
point connection! It has but two ends. One end is attached to the "screen"
(well a process in the TDS:think it maps straight through to the server,
but I don't recall..), the *other* end *should* be connected to a single
occam process.
What worries me about your example is that you managed to compile it and try
to run it! I know that for a variety of reasons the 'screen' and 'keyboard'
channels in the TDS are treated less rigorously than normal occam channels:
maybe you fell through that hole?
(Proc1) ------\
\ [???????????]
/[some horrific non-occam,non-transputer]----- screen
(Proc2)------- / [joint!]
This is more than pedantry: the way the transputer implements channels
whether in memory (in this case) or on a link engine (eventually when
going out to the server on the PC) guarantees that your attempt will
fail, as indeed it did!
If you really want to achieve something like this when talking to a sequential
machine like a PC , one way is to put a multiplexing process between the
TDS screen channel, and your two 'virtual screen' channels. But I suspect
that you will decide that this wasn't really what you wanted to do anyway!
Hope this throws some light on the matter!
Adrian Lawrence
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