Homework-5b

Homework-5b

Due Date: Nov 14th, 2007 (Midterm Exam-1)

A control unit is the part of a CPU or other device that directs its operation. The outputs of the unit control the activity of the rest of the device.
The control unit is the circuitry that controls the flow of information through the processor, and coordinates the activities of the other units within it. In a way, it is the "brain within the brain", as it controls what happens inside the processor, which in turn controls the rest of the PC.

At one time control units for CPUs were ad-hoc logic, and they were difficult to design. In modern computers, the registers, arithmetic and logic units, instruction registers, buses, and off-chip input/output may have its own subsidiary controller, with the control unit acting as a supervisor.

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 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.

Mathematician John von Neumann proposed the ALU concept in 1945, when he wrote a report on the foundations for a new computer called the EDVAC.