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From: freed@aum.UUCP (Erik Freed)
Newsgroups: net.arch,net.micro.68k
Subject: Re: Asynchronous State machines
Message-ID: <393@aum.UUCP>
Date: Sun, 27-Oct-85 11:35:06 EST
Article-I.D.: aum.393
Posted: Sun Oct 27 11:35:06 1985
Date-Received: Wed, 30-Oct-85 04:26:28 EST
References: <389@aum.UUCP> <935@turtlevax.UUCP>
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Organization: The Aurora Systems Bunch
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Xref: watmath net.arch:1963 net.micro.68k:1268

> In article <389@aum.UUCP> freed@aum.UUCP (Erik Freed) writes:
> >I have received some mail requesting further info on Asyncronous state
> >machines. I wish that there were some great book on it that I could
> >give a pointer to, but I don't know of one. There are some papers such as
> >
> 
> I don't know what this is doing in net.micro.68k, so I took the liberty
> of redirecting all followups into net.arch only.

I sent it to the newsgroups where the question of vmebus metastable "glitch"
problems were being discussed. I sent it also to net.arch.

> 
> The one signal that can be used is one such as the SYNC signal
> that is used on all asynchronous buses to validate the address
> on the bus.  Once the data has been written or gated onto the bus,
> an ACK signal is passed back to acknowledge the transfer.
> -- 

I think that you missed my point. First of all I don't think that you are
talking about any Vme bus I have worked with. The Vme bus AS signal cannot
do much for you except in rare circumstances (address only cycles). The
place for the asynchronous state machines are where you have many state
machines performing complicated functions such as a bus requester where
you have to juggle many async inputs from the bus and you want high speed.
the single input dependancy trip is to make sure that you jump from state 
to state without getting confused. (inputs also include the state bit outputs)
The paper I listed talks about the "One Hot" method which details a method
which involves state transitions which go 010 011 001 for a change from
state 2 to state 1 (state 3 is not a valid state because more than one
state bit is "hot" at once. 
-- 
-------------------------------------------------------------------------------
                           Erik James Freed
			   Aurora Systems
			   San Francisco, CA
			   {dual,ptsfa}!aum!freed