On 6/14/2018 2:44 AM, smf wrote: > On 14/06/2018 06:02, Jim Brain wrote: >> If you can guarantee the NMI will occur (I think Marko showed that >> you can trigger it and not ack an NMI, which would hold the NMI line >> down, preventing NMI from working), then your idea would work. > > To work round that you need to copy the Trilogic Expert ESM circuit. > > > https://people.kth.se/~e93_msi/c64/expert.png If that is the circuit referenced, it looks like it just "fights" the low value and brings it to a high via the 74ls125. If I am reading the datasheet correctly, it can supply 100mA of power to the !NMI line to pull it high, so I assume this circuit just overwhelms the NMOS driver to ground. If I am correct, that does not sound healthy to a CIA. -- Jim Brain brain@jbrain.com www.jbrain.comReceived on 2018-06-15 06:00:04
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