31 Aug
2005
31 Aug
'05
11:50 a.m.
Subject: Re: 6800 opcode $02
From: "Dwight K. Elvey" <dwight.elvey at amd.com>
Date: Wed, 31 Aug 2005 09:44:34 -0700 (PDT)
To: cctalk at classiccmp.org
Hi
On the 8080, one just has pullups on the bus and
it will do continuous restart interrupts. This
will cycle through the addresses for the push part of
the instruction. This is handy for testing address
decoders, especially when working with boards of
unknown design.
I wasn't aware that the 6800 had a similar method.
Dwight
Not quite the same. The 8080 RST (also works for z80 and 8085)
will revert to normal operation if rom(or any instruction source)
is encountered. The HCF required hard reset to escape as it
was not a useful instruction. Hence the name Halt and Catch Fire.
Allison