Central Processing Unit (CPU)

Does all of the work for the computer

1. Does all of the mathematics, mainly addition
2. Does all the logical comparisons of values
3. Directs the flow of data in a computer
4. Controls the operation of the parts of the computer
   
   

Today, all  CPUs are microprocessors

1. A microprocessor is a complete computer on a silicon chip  
2. A microprocessor does all of the functions of a computer
• stores data and instructions waiting to be used
• follows changeable instructions
• does input, processing, and output
  
  

CPUs have three basic parts

1. The Arithmetic Logic Unit (ALU)
• does all of the mathematics in a computer
• does all of the logic comparisons of values
• some common logic comparison symbols
• = equal to
• < less than
• > greater than
• <= less than or equal to
• >= greater than or equal to
• <> not equal
  
  
2. The Control Unit
• directs the flow of information into the CPU and/or memory or storage
• controls which instructions the CPU will do next
  
  
3. Registers
• Used to store data and instructions inside the processor
• Size of the registers can affect the speed and performance of the processor
  
  

Speed of CPUs

1. The speed of CPUs is measured in hertzs.
• A hertz is on cycle per second.
• Need to measure time to determine cycles per second
• All computers have a clock built into them for timing the cycles
• The clock is usually located in a small metal box on the motherboard.
• Today, many CPUs can complete over six (6) instructions per second.
  
  
2. Speeds of modern CPUs
• Most computers have a CPU that can do more than 400 MHz.
• MHz stands for megahertzs
• A MHz is 1,000,000 cycles per second.
• Computers will soon be at speeds of over a gigahertz, 1,000,000,000 Hertzs.