Quote:
Originally Posted by Mark1960
What value resistor did you use for the RC delay to the Buffers?
With two 74ls ttl inputs on the output of the RC delay, the maximum resistor value is probably 1 k to make sure it can pull the inputs down to less than 0.8 v. A lower value, say 470 ohm might be a better choice, but then the capacitor needs to be a higher value.
I was never much good at calculating RC timing values, I think you want to aim for about 1.5 to 2 us. Based on 8060 memory cycle time at 4MHz.
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I suggested a 1k resistor, so C should be 1.5-2nF, looks like I suggested a value far too small.