Quote:
Originally Posted by Mark1960
What is the input circuit on the Triton? If its standard ttl or even ls ttl then 2.7 k pull down might not be strong enough to pull down to less than 0.8 v. Ideally you want them to pull down to 0.4v or less. Most of the ttl inputs had diodes to protect the input from undervoltage, so the 2.7k pull down to -12v is probably going to be ok as the 2.7 k resistor would limit the current into the input diodes of the ttl.
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The input to the Triton is via IC49 a 74LS244
Triton ports circuit diagram
I found a problem with this chip on my Triton pin 11 (strobe) was bing passed through to pin 9 (DB8) even when both select pins are high. This had the effect of holding DB8 near zero when the Keyboard was plugged in, that took me some time to find when checking out the data bus.