In computing, an arithmetic logic unit (ALU) is a digital circuit that
performs arithmetic and logical operations. The ALU is a fundamental building
block of the central processing unit (CPU) of a computer, and even the simplest
microprocessors contain one for purposes such as maintaining timers. The
processors found inside modern CPUs and graphics processing units (GPUs) accommodate very powerful and very complex ALUs; a single component may contain
a number of ALUs.
John von Neumann proposed the ALU concept in 1945, when he wrote a report on the
foundations for a new computer called the EDVAC. Research into ALUs remains an
important part of computer science, falling under Arithmetic and logic
structures in the ACM Computing Classification System.