I am working out the ideal RTL NOR circuit to use as universal gates for a large project.
Based on what I've found on Wikipedia, to implement a NOR gate using BJTs and resistors, we have the following:
In this case, R3 & R4 provide paralell input to the base of the transistor. We can ignore R1 as it really isn't required for silicon transistors.
Inputs A and B seem to supply the same 5V whether they are both high or not right? To test it, I have implemented this NOR gate like this:
The pullup resistor is 1K ohm and the input resistor that both inputs go through is 10K. The transistor is a 2N3904.
I've tested this NOR gate and the truth table it yields is right on for NOR. I'm wondering if this simplification has any implications that I'm missing. Is there a specific problem with fan-in here? Ideally, I'm looking for the simplest circuits for mass production. I would like to avoid any complications that may arise when combining many NORs to produce other gates.