Re: Signature Analysis without a CAT box

That's what I get for not double checking...I had read that somewhere
recently and hadn't gotten around to checking it out. I made up regular
NOPs by hardwiring a number of CPUs into their permanent NOP state (and a
simple RESET so that was separate from the UUT (Unit Under Test) so the
watchdog could be ignored to some extent. (Best to disable it)

John :-#)#

At 12:28 AM 03/07/2003 -0700, Zonn wrote:

>On Wed, 02 Jul 2003 09:58:12 -0700, John Robertson <jrr@flippers.com> wrote:
>
> >A NOP is a NOP. Simply hardwire a 24 pin header to the required
> >configuration and install it in the boot ROM socket.
> >
> >It seems for a Z80 that all you have to do is remove the boot ROM and as
> >long as the DATA lines are all pulled high then it will happily NOP...
>
>Actually the lines would need to be pulled low. The Z-80 used all 0's for a
>NOP, which was pretty cool when patching EPROMs, since you could always
>write a
>00 to any location in an EPROM without having to erase it first.
>
>-Zonn
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Received on Thu Jul 3 03:51:54 2003