21 Jul
2010
21 Jul
'10
10:20 p.m.
On 21/07/2010 22:22, Eric Smith wrote:
JP Hindin wrote:
Hmm.. I've definitely done it, and on quite old parts on occasion. I
thought they were NMOS but they may have been CMOS, I suppose. And I
recall being told in the late 70s or possibly around 1980/81 that Z80s
were static -- that would be about the time I started poking at the
hardware in that sort of detail.
Has anyone -tried- hand-clocking a Z80?
Won't work on an original NMOS Z80 CPU, they were definitely dynamic.
You could get away with somewhat slower than the minimum spec (about
246.3 kHz for a 4MHz NMOS Z80), but not at finger speed.
Some of the later CMOS Z80 cores are static, some are not. In
particular, the original Z180 was CMOS but dynamic. It may be the case
that all CMOS Z80 CPUs (vs. Z180 and other derivatives) are static, I'm
not sure. Check the data sheet for the specific part number you're using. If you hand-clock a static CPU, remember to debounce
your button or
switch. Switch bounce can have glitches faster than the minimum clock
pulse width spec; I've seen them on an oscilliscope many times. Even
if you don't get fast glitches, you'll still get multiple pulses when
only one is desired.
That is definitely true.
--
Pete Peter Turnbull
Network Manager
University of York