CPU

CPU

1. ALU

   • Arithemetic logic unit
     • An ALU performs basic arithmetic and logic operations. Examples of arithmetic operations are addition, subtraction, multiplication, and division. Examples of logic operations are comparisons of values such as NOT, AND, and OR.

2. control unit

3. special process registers

   • MAR, MDR, PC, CIR
     • MAR is the CPU register that either stores the memory address from which data will be fetched to the CPU or the address to which data will be sent and stored
     • MDR
       • memory data register
         • The MDR is a two-way register. When data is fetched from memory and placed into the MDR, it is written to go in one direction. When there is a write instruction, the data to be written is placed into the MDR from another CPU register, which then puts the data into memory.

4. CIR

   • current instruction register

5. pc

   • program counter