In computing, an arithmetic logic unit (ALU) is a digital circuit that performs arithmatic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers. The processors found inside modern CPUs and GPUs have inside them very powerful and very complex ALUs a single component may contain a number of ALUs.-In computing, an arithmetic logic unit (ALU) is a digital circuit that performs arithmatic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers. The processors found inside modern CPUs and GPUs have inside them very powerful and very complex ALUs　a single component may contain a number of ALUs.