adder

Adder is a common name used for two distinct topics: a group of venomous snakes and a class of digital circuits that perform binary addition. In zoology, adder refers to several snakes in the family Viperidae, with the European common adder (Vipera berus) being the best known in Europe. In electronics, an adder is a circuit that adds binary numbers, a fundamental operation in computer hardware.

Vipera berus, the common adder of Europe, is a medium-sized viper typically up to about 60 cm long, with a stout body and a distinctive zigzag dorsal pattern. It inhabits woodlands, heaths, and damp habitats and is generally shy, avoiding humans when possible. Bites can cause pain and swelling and may produce systemic symptoms in some cases; antivenom is used for severe envenomation. Adders feed on small mammals, birds, lizards, and amphibians and hibernate during winter in dens. They are viviparous, giving birth to live young after a gestation period.

An electronic adder is a circuit that adds two n-bit binary numbers. A half-adder processes two input bits to produce a sum and a carry, while a full-adder also incorporates a carry-in bit to produce a carry-out. Multi-bit adders are built by chaining full-adders, forming ripple-carry adders that are simple but slow, or more advanced carry-lookahead and carry-select adders that reduce propagation delay. Adders are core components of arithmetic logic units in CPUs and other digital systems, enabling arithmetic operations, address calculations, and data processing.