4.7.1.1 Internal hardware components of a computer

A computer is made up of many individual components.

Some components include:

  • Processor
  • Main Memory
  • Address Bus
  • Data Bus
  • Control Bus
  • I/O Controllers

Processor (CPU)

The processor is a component within a computer which performs all of the computation and calculation. It can be thought of the "processing" part of a brain.

Main Memory (RAM)

The main memory in a computer stores data temporarily for use by the processor.

Address Bus

This "bus" is a set of wires which identifies the address that is being targeted by the CPU.

Data Bus

This bus sends and returns data to and from all the components which may require data.

Control Bus

A set of wires which determines the state which the main memory acts as, such as read or write.

I/O Controllers

A component which interacts with other parts of the system.

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Von Neumann Architecture

The Von Neumann Architecture is an architecture of computing where both data used for programs, and the programs themselves are stored within the same main memory.

Advantages include:

  • Easier to handle

Disadvantages include:

  • CPU has to wait for instructions to arrive, then data
  • Data can be accidentally interpreted as a program

It can be represented in a "Three box model". The diagram represents the data bus in which all three components, the CPU, Main Memory and I/O all communicate on.

Three box? More like 3 box and 4 arrows

The Vonn Neumann architecture is the architecture most alike our computers today.

Harvard Architecture

The Harvard Architecture has separate memory stores and busses for data and programs.

Advantages include:

  • CPU can simultaneously fetch instructions and programs

Disadvantages include:

  • Hard to program for
  • More space is required, as there are two busses and stores

Types of CPU

There are two types of CPU - CISC, or Complex Instruction set Computing, and RISC, or Reduced Instruction set Computing. Main differences include:

  • Number of instructions

    • RISC has less instructions than CISC. CISC CPUs have more "complicated" instructions, so can achieve some tasks using less operations.
    • CISC CPUs will need to combine multiple instructions to perform the same task.
  • Size

    • As CISC CPUs have more instructions, more silicon is required to support this.
  • Clock Speed

    • RISC CPUs commonly run with a lower clock speed compared to CISC CPUs
  • Energy Consumption

    • CISC CPUs consume more energy compared to RISC CPUs.