21 Jul
2010
21 Jul
'10
3:51 p.m.
Dave McGuire wrote:
On 7/21/10 1:17 PM, JP Hindin wrote:
The only problem I could see is if the RAM memory is dynamic and one
made the mistake of single stepping the board master clock rather than
the Z-80 CPU clock. Static RAM wouldn't care...
John :-#)#
I was reading something the other day about being
able to hand-clock a
Z80, that it was so stable (due to not using dynamic registers,
apparently) that with the appropriate debounce circuit you could literally
manually step it through instructions.
Is this as rare as it sounds?
Has anyone -tried- hand-clocking a Z80?
Umm yes, it's called single-stepping, and it's very common. The first
Z80 system I had that had support for that built-in was my IMSAI 8080.
I used single-stepping to debug my BIOS modifications in the mid-1980s.
And yes my IMSAI "8080" is actually a Z80 system...It has a CCS 2810
CPU board which is compatible with the IMSAI front panel circuitry. :)
A single-stepping circuit for a Z80 is pretty simple.
-Dave