🚀 go-pugleaf

smckinty@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC) writes:

>In article <1992Sep15.150015.7409@sbctri.sbc.com>, tadams@sbctri.sbc.com (Tom. Adams 529-7860) writes:
>> I was wasting time in a meeting, and came up with an idea that seems
>> interesting to me.  Consequently I'm sure it's been done, or more likely
>> been shown to be just incredibly stupid. :)
>> 
>> I'd like to connect multiple devices to an RS232 line, buswise.  All devices
>> would either be programable, (i.e. PC's) or be frontended by a (cheap)
>> microprocessor.  I'm wondering if CSMA/CD is a reasonable way to manage 
>> very low speed bus contention.

You could do CSMA/CA, and get away with using stock hardware. The idea is
that you send a short "reservation" packet, and require the destination
to respond to it. If you don't get a response within a short time, you
assume a collision and back off. The advantage is the lack of special-
purpose hardware; for instance, you could use PC serial ports.

See the description of the Localtalk protocol in "Inside Appletalk" for
more details - that's the scheme they use, probably for cost reasons.

				Peter Desnoyers
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