Central Processing Unit & Computer Program

Two main components
   - Arithmetic and logic unit (ALU)
   - Control unit (CU)
   - Registers are used as scrap paper – intermediate results
Speed measured in hertz
   - Megahertz – millions of instructions per second
   - Gigahertz – billions of instructions per second

Computer Program Instruction Execution
- Connect all the pieces together
   - Bus – electrical pathway
   - All digital data moves from component to component on the bus
- Executing an instruction
   - Control unit fetches next instruction from primary storage and stores it onboard the CPU
   - The control unit decodes the instruction
   - The ALU executes the instruction possibly accessing other data in primary storage
- Cycle is repeated millions of times per second

Types of Computers:
- Supercomputers
- Mainframes
- Minicomputers
- Workstations
- Desktop computers
- Notebook computers (laptops)
- Handheld computers (PDAs)

How Program Running on Computer




Moore's Law