Re: Speculation on ARM licensed by DRAM companies
- To: wmor1@xxxxxxxxxxxxxxxxxxxxx
- Subject: Re: Speculation on ARM licensed by DRAM companies
- From: "Robert J. Brown" <rj@xxxxxxxxxxxxxx>
- Date: Mon, 21 Jul 1997 09:41:23 -0500
- CC: misc
- In-reply-to: <44E97B660F6@hfs01.cc.monash.edu.au>(wmor1@student.monash.edu.au)
>>>>> "wmor1" == wmor1 <wmor1@student.monash.edu.au> writes:
wmor1> Question? how hard (extra equipement) would it take to
wmor1> drive ethernet off the F21 chip. I had thought about
wmor1> protocols that would avoid the collision aviodance problem
wmor1> on ethernet that would get around the performance drain of
wmor1> to many senders on the network. Actually I rember
wmor1> something about being able to implement rings and ethernet
wmor1> over the same networks. The reason why is that something
wmor1> like it would make an interesting bus.
The collision problem on ethernet and the collision problem in hash
tables are both essentially the same thing, except that one is a
collision in address space and the other is a collision in time
space. Schemes to avoid collision invariably involve some sort of
token passing protocol. The overhead for hash tables implies
significant efficeincy degradation at over about 75 % utilization.
Ditton for ethernet collisions. It should not seem strange to you
then that the overhead of token passing is about the same also. The
trick then is to use a bus with 33% more bandwidth than you actually
need. This will eliminate most collisions, or alternatively provide
the extra overhead for a robust token passing protocol. I prefer the
ethernet approach, since it is amenable to RF transmission over open
air also.
--
-------- "And there came a writing to him from Elijah" [2Ch 21:12] --------
Robert Jay Brown III rj@eli.wariat.org http://eli.wariat.org 1 847 705-0424
Elijah Laboratories Inc.; 37 South Greenwood Avenue; Palatine, IL 60067-6328
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