System architecture

GCSE Computing

Clock

Clock sends timing signals to synchronise all components involved in the fetch-decode-execute.

Control unit

Controls all the activity in the CPU / Controls the whole fetch-decode-execute cycle (by sending control signals). Decodes the instructions.

Register

Storage for a single instruction (the current one that need to be carried out). Stores the result of a calculation, addresses

ALU

Performs mathematical calculations, such as addition and subtraction, and logical operations. It processes data as instructed by the control unit, enabling the CPU to solve problems.

Control bus

Carries signals from the control unit to other components to manage operations. It transmits commands like read, write, or interrupt signals, ensuring coordination between the CPU, memory.

Data bus

Transfers actual data between the CPU, memory, and other devices in both directions. It acts as a pathway for moving data, such as instructions or results, during processing.

Address bus

Carries memory addresses from the CPU to the memory or other devices. It specifies the location where data should be read from or written to, ensuring the correct memory location is accessed.

Increasing clock speed

Allows the CPU to execute more instructions per second, as it generates more electrical pulses to synchronize operations, improving the overall processing speed and performance of the computer.

More cores

Enable the CPU to handle multiple tasks simultaneously by dividing workloads across separate processing units, improving multitasking and performance for parallel processes.

More cache

Provides faster access to frequently used data by storing it closer to the CPU, reducing the time spent fetching data from slower main memory (RAM), thus speeding up processing and efficiency.

Fetch

Instructions and data are taken from RAM and passed to the CPU. The address of the item is placed on the address bus, and the control bus is set to read

Decode

The control unit examines the instruction and works out what it needs to do next.

Execute

An instruction is carried out. It might involve mathematics using the ALU circuits, or it might involve writing the result of a calculation into RAM, or into an internal register

RAM

Used to store the instructions and data for the currently used programs (FDE cycle) - volatile

ROM

Permanently stores the boot-up instructions which the computer uses to start up and cannot be easily modified.

Secondary storage

Provides long-term, non-volatile storage for data and programs, stores programs and files that are currently in use.

Main memory

Holds the data, instructions, and programs currently in use by the CPU, enabling fast access during processing but losing data when powered off.

Cloud storage

Used to store the instructions and data for the currently used programs (e.g. Fetch, decode, Execute Cycle).