Computer System: The CPU

Computer System: The CPU

The CPU (Central Processing Unit)

  • The CPU is often called the ‘brain’ of a computer system as it carries out most processing.
  • It performs two main tasks - executing program instructions and managing hardware resources.
  • Every instruction that a CPU understands is given a unique instruction code.
  • The speed at which the CPU processes data is called the clock speed, measured in gigahertz (GHz).

CPU Components

  • The Control Unit controls and monitors the operations of the hardware.
  • The Arithmetic Logic Unit (ALU) is where the actual computations take part, such as performing arithmetic and logical operations.
  • Registers are small storage areas which hold data that is currently being processed.

CPU Cores

  • A core is an independent unit within the CPU that can perform operations separately.
  • A single CPU may contain multiple cores, enabling it to execute multiple instructions at the same time. This improves overall performance and speed.
  • Processors with multiple cores are known as multi-core processors. They are faster and more efficient than single-core processors.

CPU Performance

  • The performance of a CPU depends on several factors, including the clock speed, the number of cores, and the architecture of the CPU.
  • A higher clock speed allows a CPU to execute more instructions per second, however, high clock speeds generate more heat.
  • More cores allow a CPU to perform more simultaneous operations, but not all tasks can take advantage of multi-core processors.

The Fetch-Decode-Execute Cycle

  • The Fetch-Decode-Execute Cycle is the process that the CPU uses to retrieve and execute instructions.
  • During the fetch stage, the CPU retrieves the instruction from its memory.
  • In the decode stage, the CPU interprets what the instruction means.
  • During the execute stage, the CPU carries out the instruction.
  • The cycle then repeats for the next instruction.

Von Neumann Architecture

  • Developed by John Von Neumann, this architecture describes a design where the CPU contains the Control Unit, Arithmetic Logic Unit, and Registers.
  • In this architecture, both data and instructions are stored in the same memory system. It is the basis of most modern computers.
  • The fetch-decode-execute cycle is a key principle of the Von Neumann architecture.