Computer Science Comp 1 CPU - created from Mind Map

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Factors affecting CPU

Fetch/Decode/Execute Cycle

Roles of the CPU

Components

Cache

Registers

Cache size - more space to hold instructions

Clock speed - more cycles per sec

Number of Cores - more instructions can be executed

Fetch - Receive instruction from a memory address

Decode- Identify the operation from the instruction

Execute - Link up parts of the CPU needed to carry out operation

• Receives instructions from the computer

• Processes received instructions

• Executes programs

• Manages computer hardware

• Handles communication between components

Buses - Parallel wires connecting 2+ independent components of a computer system to pass signals.

Control Unit - to send control signals between different internal components

Arithmetic Logic Unit - to perform arithmetic and logic calculations using +,-, AND, OR

Cache - high speed memory used to store data before it is processed by the CPU

Peripherals - any devices, not directly connected to the CPU e.g. Mouse, keyboard, printer, hard disk.

Secondary Storage devices - external devices used for storage e.g. Hard disk drive, Solid State Drive, Flash Memory, DVD-R and Blu-Ray

Embedded systems aka firmware are combinations of hardware and software that perform a specific function or perform specific functions within a larger system. Central heating control system, dish washer, washing machine, digital TV.

Address Bus - sends the addresses (locations) of data from the processor to main memory. 1 way.

Data Bus - sends the data for processing/storing to and from main memory. 2 way

Control Bus - sends signals to and from the control unit to other parts. 2 way

Level 1 cache is the fastest and stored on the CPU

Level 2 is also on the CPU, but may serve several cores

Level 3 is separate from the CPU but closer than the RAM

MAR - Memory Address Register - records the memory address of the data to be fetched or stored

MDR - Memory Data Register - stores data after being fetched from Main Memory

PC - Program Counter - contains the memory address of the next instruction

CIR - Current Instruction Register - Copied from the MDR, holds the current instruction to be executed

ACC - Accumulator - stores the result of calculations