Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site aum.UUCP Path: utzoo!watmath!clyde!cbosgd!ihnp4!mhuxn!mhuxr!ulysses!allegra!mit-eddie!think!harvard!seismo!lll-crg!well!ptsfa!aum!freed 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> Distribution: net Organization: The Aurora Systems Bunch Lines: 37 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