2 Jul
2012
2 Jul
'12
2:31 p.m.
On 07/02/2012 01:34 PM, Dave McGuire wrote:
On 07/02/2012 01:24 PM, Chuck Guzis wrote:
I haven't gone and checked, but I do
recall pretty clearly that they
specify a 330 ohm pullup on the clock line of a Z80, not 10K.
-Dave
All the circuits (including the Zilog manuals) I've seen use a 330 ohm or
CMOS (rail to rail drive), or something like the 75452 drivers. The key
thing is the clock must get to 4.75V nominal (4.4V minimum) with a
reasonable rise time and fall times for the clock speed. Most TTl will
not go much above 3.4-3.6V without help (pull up).
Allison
Output
-> VCC 5.23 MOhm
Output -> GND 5.20 MOhm
VCC -> Output 11.21 MOhm
GND -> Output 11.20 MOhm
Interesting--so they're apparently using a
"naked" totem-pole output
stage with no pullup. Interesting--I thought that Zilog always
specified at least a 10K pullup on the clock input.
Rules were made to be broken, I guess.