Storage#

Gates remember.

Cross-couple a pair of gates so each drives the other, and the arrangement will hold a state after the input that set it is removed. That feedback is the origin of memory in digital hardware. Latches are level-sensitive; flip-flops add a clock so state changes only at a defined edge — the discipline that makes large synchronous systems predictable.

Sections#

• SR Latch — The basic set/reset feedback cell.
• D Latch — Transparent when enabled; captures one data line.
• D Flip-Flop — Edge-triggered capture: the standard register bit.
• JK Flip-Flop — The historically general-purpose flip-flop, including toggle.
• T Flip-Flop — Toggle on each clock: the building block of counters.
• Registers — A row of flip-flops clocked together to hold a word.