How Computers Work

What is a Computer?

• A computer is an electronic device that takes in data, processes it, and outputs the result.
• Examples of computers include desktop computers, calculators, mobile phones, smart watches, and iPads.
• Input devices such as a mouse, microphone, and Xbox controller send data/instructions into the computer.
• Sensors are input devices that monitor changes in their environment, record the information, and send it to a computer.
• Output devices such as a speaker, printer, and screen receive information from the computer.

Hardware and Software

• Hardware refers to the physical elements of a computer.
• The motherboard sends messages to all of the other components inside the computer.
• The processor/CPU is where the computer carries out all of its tasks.
• The computer casing holds everything together and keeps each of the components in place.
• The power supply pumps electricity around the computer to power all of the components.
• The hard disk drive is where all of your documents, pictures, programs, etc. are stored on the computer.
• RAM (Random Access Memory) is where the computer stores the current task that is being carried out.
• Software is used to describe the programs that run inside your computer.
• The operating system is software that manages a computer's hardware and provides a user interface.

The Central Processing Unit (CPU)

• The CPU is often known as the processor and is found on the motherboard.
• The CPU performs calculations and coordinates hardware (such as the mouse and keyboard).
• All CPUs have a clock speed, which is the number of instructions the CPU can process in one second, measured in Hertz (cycles per second).
• The Fetch-Decode-Execute cycle is a process where the CPU:
  • Fetches program instructions from the RAM.
  • Decodes the instructions and makes sense of them.
  • Executes (performs) difficult calculations or moves data from one memory place to another.

The CPU, RAM, and I/O Devices

• When you open a program on your computer, you send a message to the CPU to deal with the request.
• The CPU looks for the program on the hard disk/long-term storage.
• It then takes the program and loads it into the RAM.
• The program is now ready to use.

Networks

• A network is two or more computers connected together to share information and resources.
• There are two types of networks: LANs (Local Area Networks) and WANs (Wide Area Networks).
• A LAN is a connected set of computers and other devices on one site, relatively small, and owned by the organisation.
• A WAN is a wide area network when computers or devices are connected together over a large geographical area.