This is the multi value memory cell that can store as many values as you want to, the only limit being the number of signals(-2 W and C are reserved) that exists in the game.
It has one input and one output. When the W signal @ input changes (typically from 0 -> 1 or 1 -> 0) the circuit will clear the previously stored values and store the new values being input.
Something to note is that the circuit operates on a 3 tick clock to prevent feedback, so the input has to be active for at least 3 ticks to guarantee a successful write.
Gif illustrating how it works
And lastly
Blueprint-string