Tablet PC is a culmination of advances in shrinking notebook hardware and improvements in integrated digitizers as methods of input. It’s actually a book-sized laptop without a keyboard. Instead of keyboard, a digitizer is used to input the data. The digitizer is typically integrated with the screen, and correlates physical touch or digital pen interaction on the screen with the virtual information portrayed on it. A tablet's digitizer is an absolute pointing device rather than a relative pointing device like a mouse or touchpad. A target can be virtually interacted with directly at the point it appears on the screen. It offers portability, accessibility and more natural form of input rather than its brothers, the laptops. But the bad things are the cost is high and the risk to be broken is high too.
Officially, there are three kinds of model (or design) which has known by the world: thin-slates, convertibles and hybrid. Thin-client slates is the lightest, more secure (no data storage on the slate computer)and long life tablet PC (no processor to power) which consist of a touch screen and an integrated wireless connection device. The disadvantages of this model is the limited processing power which is chiefly involved with Input/Output data processing such as video display, network communications, audio encoding/decoding, and input capture (touch screen input, bar code reading, magnetic stripe reading (credit card swipe). Convertibles is just a mere decreased-size laptop (with a keyboard and touch screen), except that its screen can be rotated 180o. The last model, hybrid, share the features of the slate and convertible by using a detachable keyboard that can be rotated, which operates in a similar fashion to a convertible when attached.
