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From: Cent.Mbeck%MIT-OZ@MIT-MC.ARPA (Mark Becker)
Newsgroups: net.micro
Subject: Re: HCF (Xref: 516@digi-g.UUCP, seismo net.micro:10351)
Message-ID: <9534@brl-tgr.ARPA>
Date: Thu, 28-Mar-85 00:25:01 EST
Article-I.D.: brl-tgr.9534
Posted: Thu Mar 28 00:25:01 1985
Date-Received: Tue, 2-Apr-85 00:08:54 EST
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Ah, yes.. the 6800 HCF.  If I recall correctly, opcodes 9D or DD would
start things running.  There were probably others... not to mention all
those "undocumented" opcodes which were nice to have around.

In mid-1975 Popular Electronics carried a front page article about a
machine MITS had just come up with using the 6800, called the Altair 680.
In the stock system (kit) sold, the RESET switch was driven by the Bus
Available line to the front panel.  If the processor ran into HCF, the
only way to reset the machine was to TURN IT OFF!

Easy fix - cut the line from the switch to the buffered BA and connect
it to ground.  But it sure startled a few people...

Mark Becker
Cent.Mbeck%Mit-Oz@Mit-Mc
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