CPU

CPU

1. General

   • Central Processing Unit - core of every computer system
   • Purpose - process data (searching, sorting, calculating, decision making
   • Two main components - control unit and ALU
   • Control unit uses electrical signal to direct system to execute instructions
   • ALU carries out all arithmetic and logical operations
   • Temporary cache is where data is stored temporarily while waiting to be processed

2. 1. Fetch

   • Fetches data from RAM to control unit, which decides what to do with data
   • Places address on "address bus" - vital hardware path
   • Data moves from RAM to CPU via hardware path "data bus"
   • Stores data in the "registers" - internal temporary memory areas

3. 2. Decode

   • CPU decodes instruction so makes sense
   • Decoding happens in control unit - decodes to "instruction set"
   • CPU designed to understand "instruction set" - specific set of commands

4. 3. Execute

   • Decoded data now processed in ALU
   • Instruction executed upon data then stored in cache and sent back to RAAM
   • Once stored in RAM, can appear on screen
   • This cycle happens over and over

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