[IMSAI Guy] grabbed an obsolete XOR gate and tried a classic circuit to turn it into a frequency doubler. Of course, being an old part, it won’t work at very high frequencies, but the circuit… ...

The AND gate has two inputs A and B. The output of the gate, A.B, depends on the two inputs according to the truth table at the right. The AND gate has a “1” output only when both A and B are 1.