On 6/15/2018 2:54 AM, smf wrote: > On 15/06/2018 04:52, Jim Brain wrote: >> 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. > > It's obviously out of spec, but the question is whether the output FET > will suffer damage. The spirit of commodore 8 bits is to ignore the > assumed rules and do what works. Which they could afford to do, since they owned a fab making replacement chips. I think I'll pass on using this circuit, as I consider it patently abusing the !NMI line > > The ESM button works & I've never seen a warning about it. Although I > accept that pressing the button is a relatively rare event. From a use point of view, given that we each have a few machine spares, I think it's fair to continue using it. But, I can't put my name on a design or produce a board that uses such a circuit. JimReceived on 2018-06-16 02:01:44
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