Central Processing Unit (CPU) MATTHEW BOWEN

Function  The function of the CPU is to execute all of the commands and calculations or “processes” that are stored in the computers memory.  It does this by using transistors to control the flow of electricity, like switches, to switch the transistors state between 1 and 0. This is how the computer recognises binary.

Components CPUs consist of:  Arithmetic Logic Unit (ALU)  Control Unit  Register Array  Buses (to transport the data)

Arithmetic Logic Unit  Using the ALU, a microprocessor can perform mathematical operations such as addition, subtraction, multiplication and division.  It works in conjunction with the register array for the majority of these, in particular the accumulator and flag registers.

Control Unit  This is the most complicated part of the CPU. It is responsible for controlling the operations of the rest of the processor.  It does this by sending control signals to other areas of the processor, instructing them on what to do next.

Register Array  A single register is small memory located within the CPU itself. It is designed to be able to retrieve data quickly. Processors normally contain a “register array” which house many registers, containing instructions, data and other values that may need to be quickly accessed during the execution of a program.

Buses  Buses carry data between all of the components of a processor

Cache  Cache is used for temporary storage in computers. The idea is that it is located close to the processor as it reduces latency when retrieving data as opposed to getting data from the RAM.  The greater the cache size the more that can be stored inside it.  There are 3 types of cache L1, L2 and L3. L1 is the smallest and fastest using SRAM as opposed to DRAM which is used in the main memory. L2 is bigger and located further away. L3 is rarely seen now as its job has been taken by L2.

Clocking  Clock speed is the operating speed of a computer or its microprocessor, given in cycles per second (megahertz).

Cores  If a processor has multiple cores or is “multicore”, it means that it has multiple processors together to be able to process multiple things at once. For example, if you had only one core then having anything more than one process, like a word document, running then it would cause the machine to lag. However having a second core means that the second process can be completely taken care of by the second core.