FREE LESSON · Digital logic · 3 OF 4
Registers, Flip-Flops and Computer Memory
Memory begins with feedback — Registers, clocks, and state over time
Sequential logic makes history part of the input.
Feedback allows a circuit to retain a state. Latches and flip-flops constrain when that state may change; registers group bits; a clock creates agreed capture boundaries. Between boundaries, combinational logic computes the next state from current state and inputs.
State turns a function into a process: the same input can produce a different result because history differs.
Why setup and hold both matter
Data must settle before a capture edge for setup time and remain stable after it for hold time. Violating either can leave a storage element metastable—temporarily neither a dependable 0 nor 1. Synchronizers reduce the probability that asynchronous uncertainty escapes into logic, but cannot make it mathematically impossible.
A clock coordinates state transitions; it does not abolish analog uncertainty.