 Introduction to the CPU Introduction to the CPU  Main Operations of the CPU Main Operations of the CPU  Explanation of Operations Explanation of Operations  Main components of the CPU Main components of the CPU  What determines a CPU’s performance, what to look for, for a fast CPU. What determines a CPU’s performance, what to look for, for a fast CPU.  CPU Comparison table CPU Comparison table  CPU Comparison chart CPU Comparison chart  Mr. Clarkson Talks About... The CPU (for GCSE Computing) Mr. Clarkson Talks About... The CPU (for GCSE Computing)

 The CPU is the portion of the computer system that carries out instructions of a computer program, to perform the basic arithmetical, logical, and input and output operations of the system. It acts as the BRAIN OF THE COMPUTER

 The fundamental operation of most CPUs, regardless of the physical form they take, is to execute a sequence of stored instructions called a program. The instructions are kept in some kind of computer memory. There are three steps that nearly all CPUs use in their operation: fetch, decode, and execute

 Fetch- Gets next program instruction from the computer’s memory  Decode- Figure out what the program is telling the computer to do  Execute- Perform the requested action  Write-back (Store)- Write (store) the results to a register or to memory

The ALU Microprocessor:. Registers- Stores the most frequently used instructions and data Arithmetic-Logic unit- Performs arithmetic or logical operations Accepts digital data as input, processes it according to instructions stored in its memory, and provides results as output.

What determines a CPUs performance? Data bus width- The number of pathways within the CPU that transfers data (8, 16, 32, 64) Word size- The maximum number of bits of data that the CPU can process at a time (8 bits, 16 bits, 32 bits, 64 bits) Operations per cycle (clock speed)- The number of clock cycles per second measured in Megahertz (MHz) or Gigahertz (GHz) Specifications: Clock Speed: 1.0 GHz System / Front Side Bus Speed: 133 MHz Level 1 Cache: 16K Instruction + 16K data Level 2 Cache: 256 KB

CPUGeneration ProcessNumber Data/Addres s GP RegisterMemoryInternal Technologytransistors Bus width (bits) width (bits)Bus speedClock speed Intel 80801st6.0 microns /1682 MHz Intel 80881st3.0 microns / MHz Intel 80861st3.0 microns / MHz Intel nd1.5 microns / MHz Intel DX 3rd 1.5 / 1.0 microns / MHz Intel SX3rd 1.5 / 1.0 microns / MHz Intel DX 4th1.0 microns1.2 million32 / MHz Intel DX2 4th0.8 microns1.2 million32 / MHz50-80 MHz AMD 5x864th0.35 microns1.2 million32 / MHz133 MHz Intel Pentium 5th microns 3.1 million64 / MHz MHz (P5/P54C) Cyrix 6x86 (M1) 5th0.6 microns3.0 million64 / MHz MHz (P )