# FHSST Physics/Electronics/Counting Circuits

Electronics The Free High School Science Texts: A Textbook for High School Students Studying Physics Main Page - << Previous Chapter (Magnets and Electromagnetism) - Next Chapter (The Atom) >> Capacitive and Inductive Circuits - Filters and Signal Tuning - Active Circuit Elements - Logical Gates - Counting Circuits

# Counting circuits

An arithmetic and logical unit (ALU) adder provides the basic functionality of arithmetic operations within a computer, and is a significant component of the arithmetic and logical unit. Adders are composed of half adders and full adders, which add two-bit binary pairs, and ripple carry adders and carry look ahead adders which do addition operations to a series of binary numbers.

Note: Pictures on wikipedia under GFDL

A half adder is a logical circuit that performs an addition operation on two binary digits. The half adder produces a sum and a carry value which are both binary digits.

Sum(s) = A xor B Cot(c) = A and B

Following is the logic table for a half adder:

 A B Sum Cot 0 0 0 0 0 1 1 0 1 0 1 0 1 1 0 1