A PDA is a portable digital device, often called by its English acronym for Personal Digital Assistant PDA.

Originally based on the principle of an advanced calculator, PDAs are calendar, address book and notepad. It endows them with a keyboard with small keys, or touch screen, combined with a stylus so.

According to the definition given to them, the first handheld computers (which were not then yet unnamed) are:

* The Wizard OZ-7000 Sharp (1988)
* The Atari Portfolio (1989)
* The Refalo Kyocera (1990)
* The Series 3 Psion (1991)

The first public use of the term PDA back to January 7, 1992, at the Consumer Electronics Show in Las Vegas where John Sculley introduced the Apple Newton.

Gradually technological advances allow PDAs to combine, in a reduced volume, the main functions of the office, multimedia, Internet, geo-location and telephony. Soon enough, users were able to synchronize their data with personal computers via cables. Then the wireless capabilities at the beginning limited to infrared, have been extended to access different types of networks via wireless technologies or digital mobile telephony.

As for the other computers, all these applications rely on an operating system that allows the standardization of their operations and their development.

Along with PDAs, mobile phones have also incorporated these same features. It speaks for this smartphone. If the PDA have a larger screen, but this is slightly less manageable as smartphones, they have instead readability and writing skills lower. Otherwise, the different operating systems offer usage, performance and compatibility comparable. The PDA and quickly benefited from voice recognition simplified. And innovations such as motion detector or television, appearing simultaneously. First, in direct competition, the two product families converge to form a single sector attracting large industrial and service companies in information technology and communication.

Hardware Features
A handheld is a box that has the architecture of a computer that fits in your hand, about the size of a large calculator.

As a pointing device, a stylus to select and extract information on the PDA screen. It can also write on a keyboard or directly emulated by handwriting recognition. It is then simplified written where each character corresponds to a particular movement of the stylus. To enter text via keyboard, several processes have been developed: emulated or mechanical, integrated or detachable, restricted to figures or extended to the alphabet. But the pen can still be supplemented by the use of fingers or 3D accelerometer, for example, scroll the screen information.

The internal memory (usually several mega-bytes) of some PDAs can be greatly enhanced by adding an external memory as a memory card that is plugged into the PDA (using the formats, memory cards, can store between 16 MB and 32 GB).

Communicating and mobile, handheld can integrate various types of receivers and antenna. In Europe, the following standards are used in networks based employees:

* Peer to peer: infrared or Bluetooth
* LAN: Wi-Fi
* Radiotelephony: GSM, EDGE, GPRS, or UMTS/3G HSDPA/3G +
* Positioning Satellites: GPS
* Digital Terrestrial TV: DVB-H

Operating Systems
Operating systems are the most common:

* Microsoft Windows Mobile
* Palm OS PalmSource edited by
* Symbian OS edited by Symbian Ltd.

And more recently arrived:

* Linux and Qtopia, particularly the Sharp Zaurus Linux, submitted July 14, 2002
* Android, open source system designed by Google and officially announced November 15, 2007
* IOS system designed by Apple for their iPhone, iPod Touch and iPad

Whatever the brand of PDA, thousands of paid and free software are available, including on the Internet. They can be installed within the memory of the PDA:

* Office
* Dictaphone
* E-mail, web browser
* MP3 player, image, video
* Scientific calculators
* Databases
* Managers of bank accounts
* Games
* Etc..

See also iPod touch