CPU - Central Processing Unit - processes instructions and data that are input into the computer so that the result can be output

Microprocessor = Type of integrated circuit on a single chip

Fetch-decode-execute cycle = Cycle through which data and instructions are processed

• Program Counter: holds address of next instruction
• Memory Address Register: holds address of data to be fetched
• Memory Data Register: holds data at address at MAR from the RAM
• Current Instruction Register: Holds current instruction being executed
• Control Unit:
  • It sends control signals; [1 mark]
  • … that manage the transfer of data within the CPU; [1 mark]
  • It decodes an instruction; [1 mark]
  • … using an instruction set; [1 mark]
• Accumulator - Stores interim values of the ALU

Data and information → Computer [ through input devices ] → Stored in RAM [Random Access Memory]

!! If user wants to open a file from harddrive, data will be brought from hard drive to RAM !!

Fetch Stage -

1. Program counter [PC] holds the address of the next instruction to be executed
2. The address is copied into MAR [Memory Address Register] through the address bus
3. Instruction/data at the address in MAR is copied into MDR [Memory Data Register] FROM RAM
4. Instruction/data in MDR is copied into the CIR [Current Instruction Register]
5. PC is incremented so it has the address of the next instruction