Science Fair Project Encyclopedia
A gate is a point of entry to a space enclosed by walls, or an opening in a fence. Gates may prevent entry, or they may be merely decorative.
In ancient and medieval times, gatehouses of cities and castles were heavily defended and fortified to prevent breaching of the gates. Often the gate would consist of several pairs of doors and iron grates along a tunnel through the gatehouse. The top of the tunnel commonly had murder holes to allow defenders to attack invaders trying to breach the inner doors. Drawbridges were common in conjuction with gates to facilitate passing the moat; moats were often used to increase the effective height of the walls.
In politics, the suffix -gate has been used to name a large number of public scandals lesser and greater, real or perceived, after the Watergate scandal of the early 1970s, which is still considered by many to be the worst political scandal as of 2005. Examples: Monicagate, Iraqgate .
See also: List of scandals suffixed with gate
In the context of electronic digital logic design, a gate is a logic function building block, such as and, or, not, nand, nor, xor (exclusive-or). For measuring the complexity of logic circuits such as ASICs, the amount of logic they contain is compared to a number of 2-input nand or nor gates.
Depending on technology, a 2-input nand or nor gate requires 4 or 6 transistors.
An edge-triggered D-type flip-flop is usually considered equivalent to 6 gates, more if it has clock enable and reset functionality.
- Logic gate
- Rail gate
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