- Sends control signals to all parts of the CPU and computer
- Fetches instructions from memory
- Decodes instructions
- Oversees the execution cycle
- Performs all arithmetic operations (add, subtract, etc.)
- Performs logic operations (AND, OR, compare, NOT)
- Works closely with the accumulator/registers
- Very fast storage locations inside the CPU
- Hold data, instructions, addresses, and intermediate values
- Examples: ACC, MAR, MDR, PC, IR
- Holds the address of the next instruction to fetch
- Updates automatically after each instruction
- Changes during jumps, loops, function calls
- Holds the instruction currently being executed
- Receives the instruction from memory via MDR
- Sends opcode to the control unit for decoding
- Ensures the CPU works in timed steps called "clock cycles"
- Coordinates all internal operations
- A unit of measurement meaning "cycles per second"
- Used to measure CPU clock speed (e.g., GHz = billions/sec)
- Commands the CPU understands and executes
- Examples: LOAD, STORE, ADD, JUMP
- Stored in memory as machine code