2.  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)

3.  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

4.  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

5.  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

6. 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.

7. 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

8. CPUGeneration ProcessNumber Data/Addres s GP RegisterMemoryInternal Technologytransistors Bus width (bits) width (bits)Bus speedClock speed Intel 80801st6.0 microns6 0008 /1682 MHz Intel 80881st3.0 microns29 0008 / 16164.77-8 MHz Intel 80861st3.0 microns29 00016 / 20164.77-8 MHz Intel 802862nd1.5 microns134 00016 / 24166-20 MHz Intel 80388 DX 3rd 1.5 / 1.0 microns 275 00032 / 323216-33 MHz Intel 80386 SX3rd 1.5 / 1.0 microns 275 00016 / 323216-33 MHz Intel 80486 DX 4th1.0 microns1.2 million32 / 323225-50 MHz Intel 80486 DX2 4th0.8 microns1.2 million32 / 323225-40 MHz50-80 MHz AMD 5x864th0.35 microns1.2 million32 / 323233 MHz133 MHz Intel Pentium 5th 0.8-0.0.35 microns 3.1 million64 / 323260-66 MHz60-200 MHz (P5/P54C) Cyrix 6x86 (M1) 5th0.6 microns3.0 million64 / 323250-75 MHz 100-150 MHz (P120-200)