Motorola MC14081B

Adrian Graham witchy at
Thu Dec 22 12:33:23 CST 2016

On 21/12/2016 03:23, "allison" <ajp166 at> wrote:

>> 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.

That explains the pullups I've seen on other 8085 devices I've found in
boxes recently like the Open University HEKTOR 8085 trainer.

> 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!

Binary Dinosaurs creator/curator - the UK's biggest private home computer

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