1 Jul
2012
1 Jul
'12
7:10 p.m.
On 07/01/2012 06:57 PM, Chuck Guzis wrote:
I know for a fact that a 74S04 will do the trick, as will an HCT04
with a 330-ohm pullup, as I have both of those configs running on two of
my SBCs here. Man some guys just like to bloat the BOM I guess.
Good
heavens. That's got to be the most overdesigned Z80 clock
circuit I've ever seen.
Yup--you'd think that a 74S04 would have done the trick. But the
Zilog manual cited shows pretty much the same thing--the input
feeding a resistive divider to drive a PNP-NPN "totem pole"
combination. The only really significant difference is that Zilog
uses a 10K pullup on the output.
Bizarre.
So I'm guessing that the blue lump is very much
like that.
Probably. Back in those days the communication resources between
designers were nowhere near as effective as they are today, leading to
many more instances of "designing in a vacuum" with just the datasheets
to go by, and nothing else. I don't miss that AT ALL.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA