The CPU

The CPU

1. Architecture of the CPU

   • Purpose Of The CPU
     • Central Processing Unit
     • Brain of the computer
     • decodes and executes instructions
     • Fetch Execute Cycle
       • fetch - copy memory address
   • CPU Components
     • Control Unit (CU)
       • overall control of the cpu
       • main job to manage the fecth, decode and execution program
       • Controls the flow of data inside the cpu
     • Arithmetic Logic Unit (ALU)
       • does all calculations
       • performs logic operations such as AND, OR and NOT
       • contains the accumulator register
     • Cache
       • very fast memory in the cpu, slower then the registers but faster then the RAM
       • stores regualry used data so the cpu can access it quickly next time needed, if not itll fetch from RAM
       • cache has very low capacity and are expensive compared to RAM and secondary storage
       • different levels of cache memory - L1, L2 and L3. L1 is quickest but has the lowest capacity. L2 is slower but can hold more. L3 is slowest but can hold more
     • Registers
       • Program Counter (PC)
         • holds location of the next instruction
       • Memory Address Register (MAR)
         • Holds the address of data ready for MDR or address of instruction passed by PC
       • Memory Data Register (MDR)
         • Holds the address of data thats been fetched from or to be written to the memory
       • Accumulator
         • Holds the result of calculations
   • Von Nueman Architecture
     • instructions are fetched, decoded and executed one at a time
     • Fetch next instruction -> decode instruction -> execute instructions (LOOP)

2. CPU Performance

3. Embedded Systems