[Mark1960]

Originally Posted by Slothie

It was 3.75uS according to my calculations (15 machine cycles). I think 1K & 220pF should give a delay of about 220nS so 1nF should give you 1mS?

So I think we need to aim for a delay between 2us and 3.75us, an RC on ls ttl inputs might not be that accurate without selecting the values on test.

Maybe safer to use too large a value instead of too small to avoid bus conflict, so perhaps a 3.3nF and see what that gives, then trim with the resistor.