Hand clocking CPUs

Pete Turnbull pete at dunnington.plus.com
Wed Jul 21 17:16:48 CDT 2010


On 21/07/2010 22:30, Dave McGuire wrote:
> On 7/21/10 5:24 PM, Eric Smith wrote:
>>> A single-stepping circuit for a Z80 is pretty simple.
>> True, but it is not quite as simple as hooking up a debounced pushbutton
>> to the clock, which was how I interpreted the OP's question.
> 
>   Yes, I suppose you're right.  It's much nicer (IMO) to do the full
> trick by asserting /WAIT with /M1, a flip-flop, AND a debounced
> pushbutton, though.  Then you get true instruction stepping, rather than
> cycle stepping.

Depends on what you want.  I've used a debounced switch, and sometimes 
it's more useful to step through the various T-states within 
instructions, rather than stepping an instruction at a time.  Other 
times, it's just extra tedious.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York



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