Central Processing Unit CPU The Computers Brain What

Central Processing Unit (CPU) The Computer’s Brain

What is it? • The CPU is the main component of a computer • It is made mostly of an element called silicon • The majority of calculations the computer needs to do is done by the CPU • CPU’s get very hot and are therefore often covered by a heatsink and fan

Architecture • A CPU’s mainly rated by how many calculations it can do in a certain amount of time – This is typically measured in number of calculations (cycles) per second or hertz (Hz) – Speeds of CPU’s have moved from the megahertz (MHz) to gigahertz (GHz) range – This is related to a CPU’s MIPS (millions of instructions per second) that a processor can handle • With creative and different ways of designing a CPU allows for various performance abilities

ALU • The “brain” of the CPU is the Arithmetic/Logic Unit (ALU) • This has a data width measured in bits (1’s and 0’s) • This has ranged from 8 to 64 bits • This dictates the size of the numbers and the amount of calculations that the CPU can execute at one time

Design Considerations • Hyper-Threading (HTT) / Pipelining – A CPU design which allows multiple “threads” of computations to occur simultaneously • Multi-Core – A CPU design that is actually more than one processors on one chip. – This allows a single CPU to multiply the amount of calculations in a given amount of time • Cache – Cache in terms of computers refers to a memory specially reserved to function a certain part of the computer – Since this memory is specialized it can be made faster – Different CPU’s will have different cache values • Front Side Bus (FSB) – The connection between the CPU and main memory – The larger the BUS the more information can transfer between the CPU and main memory at once

Types of CPU’s • There are two main companies that make CPU’s for personal computers – Intel – AMD • Each company makes their CPU’s differently – This gives each different advantages and disadvantages

Selecting a CPU • In selecting a CPU the following could be considered – Brand – Speed – Compatibility – Price