Aucbvax.2562
fa.info-terms
utzoo!decvax!ucbvax!info-terms
Fri Aug  7 19:57:43 1981
Re: New Concept-100/104 Software
>From Craig.Everhart@CMU-10A Fri Aug  7 15:29:14 1981
I, too, would like to cast a vote for CRC processing, which implies packetizing
at least one direction of transmission.  Using all eight bits of the data path
makes this even more important than usual.  But I'll argue for a more elaborate
protocol than just the "Line Noise" error message: the terminal's response to
a CRC failure should be to somehow induce the host into retransmitting the
garbled packet.  This puts the discussion into arguments about protocols for
error detection and correction, e.g. ACK-vs.-NAK, flow control, receiving data
out of order, and all that; but I believe that the protocols are necessary for
acceptable reliability.  Particularly with eight bits of data and crummy
dial-up lines.

Of course, with the obvious error-correction scheme, the terminal will have
to receive at least one entire checksummed packet before acting on anything
in it, which means that intensively interactive sessions (say, ordinary
character insertion into a screen editor) will have to content itself with
mostly small packets, potentially chewing up line bandwidth in the
encapsulation.  But that shouldn't really be a problem; one can package all
of an interaction-with-human into a single packet without having the bandwidth
loss get in the way.  Particularly if, when the transmission gets behind, the
backed-up characters awaiting transmission get coalesced into bigger packets.

               Craig Everhart



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