22 Dec
2016
22 Dec
'16
10:33 a.m.
On 21/12/2016 03:23, "allison" <ajp166 at verizon.net> wrote:
That explains the pullups I've seen on other 8085 devices I've found in
boxes recently like the Open University HEKTOR 8085 trainer.
If one of the
other outputs is driving a CMOS device the output may
not go high enough to satisfy it, however I would expect the reset
input on the 8085A to be TTL compatible.
The 8085 reset input is not TTL, its
schmidt trigger, and the level is
at the upper level for TTL.
If you use a 1K pullup then TTL, or open collector parts can be used as
well as CMOS. The 8085 was designed to have simple reset for cost
sensitive aps where
the circuit was usually
22K pullup and 1uf to ground.
If you using anything a 74HCxx would easily satisfy the drive and loading.
I think I've got a couple of 74HC08s that would do nicely, cheers!
--
Adrian/Witchy
Binary Dinosaurs creator/curator
Www.binarydinosaurs.co.uk - the UK's biggest private home computer
collection?