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Re: Connect AY-3-8910 sound chip to FME-7 board

Posted: Wed Apr 07, 2021 6:19 pm
by mir2sila
l_oliveira wrote:
Wed Apr 07, 2021 6:51 am
The reason for that is that regular/classic TTL chips have a tendency to assume logic level 1 when unused inputs are left open. CMOS are more sensitive to signal due to it being based on a different type of transistor (bipolar on classic TTL vs mosfet on MOS/CMOS chips) which is a lot more sensitive to input signals. Pins being left disconnected will float and serve as antenna for external static charges. Hence why approaching the finger had the effect you described.
Wow, thanks for the clarification))