Intuition Behind Storing Values

In a storage unit, you should be able to store a 0 or 1 and be able to change it.

• This doesn’t store “Q” since if the top input is 1 or 0, the Q will always be false. This means we cannot store 1. This means this is not a valid storage unit.
• However if, somehow, Q and the top input are 1, well if we switch the top input, Q becomes false, and now we can’t make it true again. Frick. stuck!

The story is similar with OR, except it stores a 1 permanently.

NAND and NOR

NAND and NOR are better:

• In the case were A=1 and Q is false, then Q becomes true. When A=Q=1, then Q=0. This oscillates and is therefore an unsteady state.
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• But the input turning $A=0$ “locks” the gate, therefore keeping the output stable (at 1)

These ideas are used to create Latches