Input devices- a piece of equipment that is used to input a piece of data or instruction into the computer

Output- equipment that is use to get data outside of the computer for viewing

 Input devices                

Optical mouse- this works by using a laser that is fired at the surface and then reflected back at the optical lenses which determines how far the mouse has moved

Voice recognition-this works by using a microphone to record analogue sound and saves it on sound drivers and turns it into digital and compares it to any function on the computer.

Keyboard-this works by depression of the keys making contact and making a current flow.

Touch sensitive-the screen is slightly electrified and when you put your finger on the screen the tiny electro signals from your finger disturb the flow on the screen allowing the device to follow your finger

Graphics tablet-this work by having 2 plates of glass and when you put pressure on the screen to draw the picture these two plates of glass are pushed together allowing a current to flow .

Camera

Device readers

Smart card reader- the card holds a small chip that when plugged into the card reader provides power to and the reader can then access the data on the chip and send and retrieve data over a secure connection.

Magnetic stripe reader-as the card is passed the reader the reader reads the way the card has been magnetised and converts that into binary and reads how much you card has and changes this to the new value.

Optical readers-this works by shining a laser at the exam sheet and where the answer is crossed out the light is not reflected and the cpu recognises this and marks you according to weather or not you got the right answer.It has to be pre-programed though to know were the right answers are.

Barcode reader-this works by each bar representing a number from 0 to 9 and the reader sends out light and waits for the reflection, the bars don’t reflect the light and the reader builds a image of the barcode up and works out the value according to the different bar sizes. Has to be pre-programed

Optical character reader-this reader is pre-programed to recognise different characters and uses the lack of reflection of light to build up the characters and then auto recognises them and turns them into text on a screen.

Radio frequency identifier reader-this works by tags sending out a small radio signal and if the tag is passed by a receiver the radio signals and sets of a current and sets off an alarm. 

finger print scanner-this works by taking a photo of your finger prints and analyzing the contors of your finger it can also be done with light.

Flatbed scanner-light is used to find where  characters are due to no reflected light then turned ito electrical signal that sets the ink use

CRT-In a cathode ray tube, the "cathode" is a heated. The heated filament is in a vacuum created inside a glass "tube." The "ray" is a stream of electrons that naturally pour off a heated cathode into the vacuum. The  high-speed beam of electrons flies through the vacuum in the tube and hits the flat screen at the other end of the tube. This screen is coated with phosphor, which glows when struck by the beam.

Plasma screen-Ech pixel is controlled by a voltage and when charged gas in the pixel is ionized turning the gas into plasma that gives off UV light that when it hit the phosphorus coated  screed turns into different tones of red green and blue.

LCD-in a LCD screen each pixel is divided into sub-pixel of  filters and when a current is passed through the liquid crystal cells a change in polarization makes light

Primary storage- is data that is lost when computer turned off and can be accessed by the processor

Secondary storage-Is storage keeps permanent copies of data and programs in a way that can be easily accessed by a computer and it can't be directly accessed by the processor

Ink jet printer-scans the image at a very fine level and sprays different amounts of red, green and blue to form an image.

Plotter-same as an ink jet printer but on a much larger scale

Laser printer-uses a laser to scan the image and like a photocopier  were tone on a drum is charged negatively and the paper is passed over the drum the charged toner is attracted to the paper.

Impact printer-is mechanical and hammers a character against the paper which hit a ink strip like a type writer

Speakers-the sound card tells the cpu to send an electrical impulse to the speaker causing a pulse in the cone producing sound.

Bit	Smallest unit (a 0 or a 1)
Byte	8 bits
Kilobyte (kb)	1024 Bytes
Megabyte (MB)	1024x1024 Bytes
Gigabyte (TB)	1024x1024x1024 Bytes billion bytes
Terabyte (TB)	1024x1024x1024x1024 Bytes

Hard disk - secondary magnetic storage that can be up to 2TB and is mainly used for storing programs and data

Floppy disk- - secondary magnetic storage that's out-date but would move files below 1.4MB around

Magnetic tape cartridge-- secondary magnetic storage that is used to back up and archive data because of its massive capacity of 800GB

USB flash drive-secondary solid state storage that replaced the floppy disc and is rapidly increasing in capacity +64GB

Memory card- secondary solid state storage that's used for cameras and it capacity is just like usb's