Peripheral: Optical mouse

The optical mouse was developed by Agilent Technologies and was released in early 2000; these mice, rather then using a ball, use a tiny camera to take around 1,500 pictures every second. (These mice are able to work on almost any surface because of the small, Redlight-Emitting Diode (LED) that bounces light off almost any surface so the camera can detect the surface of E.g., a glass table)

The mouse then sends each picture to a Digital Signal Processor to check if the surface has changed / moved from the last picture. Based on the change in pictures the (DSP) determines how each of the images differ from the last and then works out how far the mouse has moved. The mouse then sends this information to your computer and your computer then moves the mouse! Its quite amazing how fast this works, as the mouse takes hundreds of pictures per second to make this work and appear to move smoothly on your computer!

[tutorial] Computer parts and what they do [Hard Drive]

The hard disk drive is the main and largest data storage device in your computer. Everything on your computer is stored here, The OS (operating system) and all of your files.

The hard drive is sometimes referred to as the "C: drive" mainly because Windows designates the 'c' driver letter to this primary partition on the primary hard drive in a computer by default.

What is an external hard drive?

Think of an external hard drive exactly like your normal hard drive but working outside your computer. Both are extremely similar. Normally, they can be connected to your computer via a USB connection. If you have a 'pen drive'(also known as a USB stick),they work like a miniature external hard drive in the sense that they store date in an external format; an external hard drive is just like a large key-drive.