Editing Logic gate (section)

== Data storage and sequential logic ==
[[File:R-S mk2.gif|thumb|Animation of how an SR [[NOR gate]] latch works.]]
{{Main|Sequential logic}}

Logic gates can also be used to hold a state, allowing data storage. A storage element can be constructed by connecting several gates in a "[[Latch (electronics)|latch]]" circuit. Latching circuitry is used in [[static random-access memory]]. More complicated designs that use [[clock signal]]s and that change only on a rising or falling edge of the clock are called edge-triggered "[[flip-flop (electronics)|flip-flops]]". Formally, a flip-flop is called a [[bistable circuit]], because it has two stable states which it can maintain indefinitely. The combination of multiple flip-flops in parallel, to store a multiple-bit value, is known as a register. When using any of these gate setups the overall system has memory; it is then called a [[sequential logic]] system since its output can be influenced by its previous state(s), i.e. by the ''sequence'' of input states.  In contrast, the output from [[combinational logic]] is purely a combination of its present inputs, unaffected by the previous input and output states.

These logic circuits are used in computer [[computer memory|memory]]. They vary in performance, based on factors of [[speed]], complexity, and reliability of storage, and many different types of designs are used based on the application.