VLSI Concept · Fundamentals
Counters & Shift Registers
Flip-flops chained together become memory with a purpose.
A counter is a chain of flip-flops that increments its stored value every clock cycle (timers, address generation, clock dividers). A shift register is a chain of flip-flops where each stage passes its value to the next one every cycle (serial-to-parallel conversion, delay lines, and — as seen in DFT — scan chains). Both are just flip-flops plus a small amount of combinational logic.