KS3 Computing/Hardware/Input and Output

Input/Output or I/O the communication between a computer and the outside world - {{{2}}}

Would there be much point in having computers if you couldn't interact with them? Interactions with computers require devices that are built into the computer or attached to the computers. These devices are separated into input and output devices, but some devices do both, such as the touch screen. The I/O Devices communicate with the CPU and memory via the System Bus.

In order to understand how a computer works you need to understand how all these devices are connected into a computer. It is also helpful to understand how the devices are connected and communicate with the processor.


Card from a Fortran program: Z(1) = Y + W(1)

Early computers were instructed what to do using punched cards. These punched cards were also used for inputting data into the programs on the computers. Early forms of outputs from these programs included printers, bells and curve plotters. Other I/O devices evolved to make communication with computers easier including devices that you will be familiar with such as keyboards, mice and touch screens.

Various connection types have come and gone. Standards have emerged that have made some things easier, such as Universal Service Bus (USB) or Peripheral Component Interconnect (PCI).


Single system bus

Input DevicesEdit

Input I/O devices are the way in which external entities interact with a computer. Normally these external entities are people like you and I.


There are many types and styles of keyboards. Keyboards have evolved from typewriters and have inherited many characteristics including the layouts. Keyboards can be connected to a computer wirelessly via Bluetooth, or via cable using USB or PS/2. Other common forms of input are mice, gamepads and joysticks.

Space Cadet Keyboard

Output DevicesEdit

Most desktop computers, mobile phones and tablets main output device is the screen. The screen is made up of small elements called pixels. If you look closely enough you might be able to see them. Originally screens had very few colours - usually black on one other colour such as green or orange. Modern day screens can display millions of colours.

Other interesting output devices that are commonly found are speakers, headphones and printers. More recently a new technology called 3D printing has come to the fore.

Input and Output DevicesEdit

Some devices can do input and output such as modems, touch screens and network cards.


External ResourcesEdit