Also called: I/O Devices

Just having a Central Processing Unit is not enough to make a computer work. You need very very very very very special devices to input data into the CPU so that it works like you want it to, and you need very very very very very special devices to show what you are doing to the CPU so that you know what you are doing is correct. 

These devices are called Input and Output devices!!!!!!

Input Edit

What is an Input device? Edit

According to, the word put means "to move or place (anything) so as to get it into or out of a specific location or position". [1] So Input means putting something inside something. In a computer, input devices are devices that put information and instructions into the CPU so that it can run like you wanted it to.

Examples of Input devices Edit

A lot of input devices that we use involves doing something to the device so that the device can send instructions to the computer. Below are some of the most common Input devices that we use everyday.

Keyboard Edit

Das keyboard lrg

A keyboard: notice that there are buttons on the board. Every time a button is pressed, an instruction is sent to the computer for processing.

This is perhaps the most common Input Device and the Device that is the most easy to understand. A keyboard is a board that has a lot of buttons on it. When pressing a button, the information that is installed inside the key that is pressed will be sent into the CPU to process it. [2]

Mice  Edit


A mouse. The scroller is the wheel in the middle.

A mouse, in computer sense, is a device that enables the user to click on things so that he or she can access a desired program quicker. (To see the animal mouse, click here)The usual mouse consists of three buttons, the left button, the right button and the scroll (mouse wheel). In a traditional mouse, the old ones with a ball at the bottom,  traces the movement of the mouse through detecting the movement of the ball. The ball is linked to a computer chip which sends information through the wire, through the USB port, and into the CPU. The buttons on the mouse work like the buttons on the keyboard, each one with a chip under it, sending instructions into the CPU everytime the button is pressed. [3]

Microphone Edit

A microphone is a device that allows the user to input his or her own voice or sounds from the surroundings into

A microphone - users speak through the ball with the holes.

the computer. Also know as a Mike for short. As you can see in most microphones, there are holes, where you speak into. Sound vibrates a diaphragm inside the mike, which also vibrates other components inside the microphone. These components create electrical signals, which will then go through the wire, through the USB port and into the CPU for processing. [4]

Output device Edit

What is an Output device? Edit

The word "Out" is an antonym of the word "In". So, instead of putting information into the CPU, an Output device does the complete opposite. An Output device is a device that displays or information to users in an understandable format. Without output devices, we will have to understand binary numbers, which is a very hard thing.

Examples of Output Devices Edit

Output devices come in many forms, depending on the information that it needs to show. Below are some examples of Output Devices.

Printer Edit

Chip in printer

The chip in the printer.

The printer is a device that prints: that is printing words on a piece of a paper. Inside the printer, there is a small but very sophisticated computer chips

A printer.

which decodes the information from the CPU so that it can print on paper with a language we understand. After decoding, it sprays ink on specific spots on the piece of paper to create the image it needs to create. [5]

If you print this page, you would see all these words and pictures, because the chip helps decoding the computer language from the CPU. If there was not a chip inside the printer that helps you decode information, you might see something like this:




That is why you need a printer to help you convert computer language into understandable language onto a piece of paper.

Monitor Edit

Lg monitor

A computer monitor

The monitor is the device that you look at so that you know what you are doing.The device is linked to a wire called the Analog (or VGA) connector,
Monitor VGA cable

The VGA cable. Each little bit is pushed into the respective holes in the port.

which is then plugged into the VGA port in the computer, which is then linked to the CPU. Information from the CPU goes through the wire and into the monitor, which transfers the information to a picture so that it can be displayed on the screen. [6]The monitor is a vital output device for it tells us what we are doing in an understandable format, and not just in 0s and 1s.


Speaker cables.

Speakers Edit


Some examples of Speakers.

The speakers are the complete opposite of the microphone. It plays sounds that are generated by the computer. Like the microphone, the speaker has a diaphragm, which is connected to some electrical circuits. Information from the computer goes into the electrical circuits, sending electrical impulses to the diaphragm so that it vibrates, creating sound. [7]

Devices that are both Input and Output Edit

Some devices can be both Input and Output at the same time, since they display information and have the power to put in information at the same time. One such device is the touchscreen. Touch screens are screens that have a surface which is sensitive to pressure. It is an Input device in a way that when the user presses the screen, information is sent to the CPU so that it can be processed. It is also an Output device since it displays an

A touch screen - Users interact with it by touching the screen.

image to show what the user is doing. [8]

Ports Edit

What are ports? Edit

The definition of ports is: "In computer networking, the term port can refer to either physical or virtual connection points."  [9]

In the case of Input and Output devices, we mean ports as in physical ports.

The back of the computer with the ports. There are some more USB ports at the front.

Physical Ports allows physical hardware to be connected to the CPU, and are in the forms of holes in the computer. To connect the hardware with the CPU, the user will simply need to just insert the cable/wire that the hardware has into the correct port. [10]

There are different types of ports, serial, parallel, USBs and AGP.


The one on the left is a male port, and the one on the right is a female port.

Serial ports transfer data serially a bit at a time. Therefore, serial ports only need wire to transmit 8 bits. The disadvantage is that it takes 8 times longer to transmit a byte. Serial ports come in the form of 9-pin or 25-pin male connector. Serial ports are typically used to connect devices like mouse and modem.

Parallel ports can send or receive a byte (8-bit) at a time. Unlike the serial port, these 8-bits are transmitted parallel to each other, so it is faster. Parallel ports come in the form of 25-pin female connector. They are used to connect printer, scanner, CD writer, zip drive, external hard disk drive, tape backup drive, etc.

The USB is designed to save the user's trouble from deciding about which connector to use, the male or the female port. It gives you a single, standardized, easy-to-use way to connect up to 127 devices to a computer. Devices include printers, scanners, mice, joystick, digital camera, web cameras, speakers, telephones, zip drives, network connections, scientific data acquisition devices, etc.

The AGP (Accelerated Graphics Port) port is used to connect graphic cards that provides high-speed video
Agp slot

An AGP slot.

performance.These are required in games and other multimedia applications. [11]

How many physical ports are there in a computer?Edit

There are, a total of 65536 ports in the computer, some of them on the outside of the computer that connects to your input and output devices such as the keyboard and monitor. [12]

Most of these ports are internal ports, the ports that are used to communicate with software and applications. One such example is the port 80, which is a port that a web browser uses to communicate when it requires a web server. (Information from Mr. Hayes)

The Motherboard Edit


How a typical Motherboard looks like.

The motherboard is a board that is like the Mother of the Computer. It is a single board that links all the devices

This is the "bus map" on the bottom left corner are where the USB ports are located. Information from the USBs use the PCI Bus to go to the South Bridge, then to the North Bridge, and then to the CPU.

 together so that they can work together properly. It is, very much, a bridge that connects the different components inside the case of the computer together.[13]Without the motherboard, memory from the RAM could not be processed in the CPU, and instructions from a USB cannot be transfered into the CPU.

In a motherboard, there are such things called the bus circuits. Like the public transport bus, the bus circuit is the one responsible to bring information to and from devices. This is, basically how the I/O devices are

connected to the CPU.

The speed of the bus is measured in megahertz (MHz), where the faster the bus, the more information that it can handle at the same time. [14]

Form Factor Edit

One might think that Form Factor means a factor of something in the Motherboard, but it actually means the shape and layout of the Motherboard. The Form Factor affects where different components of the Motherboard are placed and the size and shape of the case where the Motherboard is placed. There are some specific Form Factors that all PC Motherboards use so that they can fit inside a normal case. [15]

Sizes have ranged from 12 inches (the oldest) to 170mm x 170mm (the newest) [16]


A scanner is a special Input Device in which it can inputs information from hard copies into soft copies so they can be edited. For example, scanning a printed document into the computer so that it can be edited. Below are some kinds of software that needs to have collaboration with the scanner in order for it to work.

OCR Edit

OCR stands for Optical Character Recognition. It is a special software that helps the scanner to convert printed text into a word processing program so that it can be edited. The words are converted into computer language, which is 100101010101110000000001011001001000101010101010101010......(binary numbers) [17]


MICR stands for Magnetic Ink Character Recognition. It is, as defined by the American National Standards Institute (ANSI),

The MICR text is at the bottom of the cheque. They are in the forms of numbers.

the "common machine language specification for the paper-based payment transfer system". [18]

This language is usually used for printing the numbers on the bottom of the check.They are printed with magnetic ink and is designed for scanners to recognize these numbers so that the information can be assessed. In checks, the numbers help the computer to process these information: check number, bank routing number and the checking account number. [19]

In order for the information to be processed properly, it needs to be printed extremely accurately, having mistakes as little to 1 line in a thousand. [20]



A finger print scanner

In the technology world, biometrics is used to recognize a person by their finger prints, iris or voice etc. This is usually used in places where high security is needed. [21]

All Biometrics devices contain the following:

  • A reader or scanning device that scans the biological information
  • Software that converts the scanned information into digital form and compares match points
  • A database that stores the biometric data for comparison [22]
They all work pretty much the same, and the good thing about these devices is that it uses your biological information to make the input device(the biometric device) in order to identify yourself so that you can access certain information. This increase security. Military, or spies (like in mission

An iris recognition device scanning the eye of someone.

impossible) uses these devices to access confidential material.

The bad thing is that it is really expensive.

References Edit