CPU stands for Central Processing Unit, and is the Heart of a computer. In any normal computer this CPU is a microprocessor. A microprocessor is a chip that does all of the calculations for the computer. The CPU contains three major parts:
  • the Control Unit (CU),
  • the Arithmetic and Logic Unit (ALU),
and the primary memory (Note: in some definitions the primary memory does not belong to the CPU).

1. Control Unit (CU)
The Control Unit controls the CPU and manages what happens inside of it.
  • Controls sequence of execution
  • Moves data between the CPU and the computer memory via the data bus
  • Controls what is stored in the cache for fastest access
  • Accesses the memory addresses with the address bus. The address bus is connected to the address section of the computer’s memory
  • Also takes care of fetching and decoding

2. Arithmetic Logic Unit (ALU)
  • Carries out logical operations (ex. Comparisons)
  • Carries out arithmetic operations (ex. Addition)

3. Primary MemoryCPU_Funktionsweise_Diagramm_copy.jpg
[see section 3.2.5 Primary Memory]

4. Buses
  • Address bus: With the address bus addresses of locations in the primary memory are transferred. The according actual information then is transferred with the data bus.
  • Data bus: Actual data is transferred via this bus. The addresses declaring which data to send or where to send the information are sent via the address bus.

5. MDR and MAR
  • These are the Memory Address Register and Memory Data Register of the CPU
  • They work together as a way for the CPU to get data out of the RAM
    • MAR
    • The Memory Address Register is there to send the address/location of a certain data point in the RAM
    • It does this over the Address Bus
    • MDR
    • Next the MDR uses this location and the Data BUS to gather the information and function as a type of cache
    • It works in two ways.
    • It can either write information it gets from the CPU into the memory
    • or it can use the address from the MAR to gather data from the RAM and keep it ready for the CPU to use it

Vocabulary review/flashcards: Quizlet.com

Last modified by: D3LTA
Last updated: 27th September 2012