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Date:      Sun, 4 Feb 1996 00:41:27 +1100
From:      Bruce Evans <bde@zeta.org.au>
To:        msmith@atrad.adelaide.edu.au, phk@critter.tfs.com
Cc:        hackers@FreeBSD.ORG, jgreco@brasil.moneng.mei.com
Subject:   Re: Watchdog timers (was: Re: Multi-Port Async Cards)
Message-ID:  <199602031341.AAA16215@godzilla.zeta.org.au>

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>> > All this is a little hypothetical just now, as I'm concentrating on the 
>> > watchdog card.  If it works out, it should do the basics, and with a TXCO
>> > on it should give a good, stable frequency reference.  Accessing it
>> > won't be fast, sorry Bruce 8(
>...
>Bruce has the 8254 data, I suspect that you would as well.  Yes, you can 
>latch everything inside it all at once.

Actually I don't have the data sheet and haven't seen it for a few years.
I seem to remember that there is an 8254 feature (automatic latch?) that
we should be using.

>Would having two counters (32 bits) be enough?  The tap points on the

Can you easily latch multiple 8254 counters at once in hardware?  I think
it would work to put them at the same address for writes and at different
addresses for reads.

Is the slowness only the usual slowness for multiple 8-bit reads?

Bruce



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