It's a grand day for Microsoft's Tablet PC's first public outing

Today (Thursday) is the day when Microsoft's Tablet PC is officially unveiled and pen technology comes of age, writes Eric Doyle.

Today (Thursday) is the day when Microsoft's Tablet PC is officially unveiled and pen technology comes of age, writes Eric Doyle.

The world is being shown the fruition of more than 10 years of trial and error to develop a device that will add to the usability of the computer. Rather than using a mouse to point and click on the screen, the tablet uses a pen, or more accurately, a stylus.

The introduction of the mouse marked a change in the way people interacted with their machines but it was not intuitive, even though most people now use the mouse without thinking. The touchpad used on notebooks was a little more intuitive but it still worked off-screen and required users to mentally convert motion in one plane to screen movements in another.

This may sound trivial but it is actually a fairly complex action requiring mental co-ordination. Pen computing is natural, the true point and click. Touch the object on the screen, tap and something happens. Move the pen across the screen and it leaves a trail of electronic ink. Press down harder and the ink trail thickens.

Microsoft has gone to great pains to de-emphasise the Tablet PC's ability to convert handwriting to text. Although the company has spent countless dollars on investigating how people in different countries write in numerous alphabets, character recognition is still too inaccurate to be trusted. It remains necessary to watch as the word is transformed to typewritten text to make sure that the job is done correctly.

In 1993, when the Apple Newton was launched, it was suggested that the perfect technology party game was to write a word, let it be converted to text, and then ask the partygoers to guess what the original word was. The miracle of conversion was insufficient, what the world needed was accuracy.

Microsoft has set itself a very hard task. The aim is not only for accurate character recognition but also for accuracy with anyone's handwriting on any machine. In the world of pen technologies we have seen many experiments: adapting handwriting to a stylised alphabet, systems that can only understand printed words rather than "joined-up" handwriting and self-adapting systems that have to be painstakingly taught the user's writing style.

None of these systems has had the freedom of Microsoft's technology where you simply start writing in your own style and the computer does all the hard work. It may not be perfect but it is impressive.

Instead, the company is promoting its Digital Ink and the ability to capture sketch maps, diagrams and handwritten text and to store it in its original raw state. So far, it sounds like a standard paper writing pad but the electronic nature of the system means that writing can be pattern-matched to find words even in handwritten form. Scribble "storage" on the screen and the search engine will seek out all words that look similar. A searchable writing pad is really something new.

At the heart of the tablet is the operating system and the hardware shell can be configured in a variety of ways. Windows XP Tablet PC Edition is the Professional version of XP with pen extensions added on top. This means that almost all applications will run on the tablet but they will need modifying to make them "pen aware".

According to Microsoft this can be a relatively trivial task of creating an overlay that is saved with the current file and stores the pen activity. Of course, new programs will probably go to a deeper level to allow character conversions but it is expected that initially pen-aware software will appear rather than pen-enabled applications.

Tablet PC ingredients

Windows XP Professional
A full version of Microsoft's operating system with a superset to cover the tablet's special features

Screen rotation
The display can be visually rotated through 90¡ to give a tall and narrow screen, like A4 paper, or the conventional short and wide display. The tablet can be rotated to be used like a clipboard

Digital Ink
This is the code that tracks the pen's movement and converts it to a trace on the screen. It records the trace as a series of geometric equations known as Bezier curves

Pen Input
The pen contains an electromagnetic coil. The screen is criss-crossed with an invisible lattice which senses the pen's vertical and horizontal co-ordinates. Using electromagnetism means that the pen can work even if it does not touch the screen, so tracing through paper is possible

Windows Journal
A new notepad to support pen input. Handwritten notes and diagrams can be stored and word searches can be performed. Notes can include images and can be converted partially or totally to text. Text files can be annotated with handwritten comments

Sticky notes
Quick reminders can be jotted down and electronically pasted on the screen - rather like 3M's Post-It notes in the real world

Speech recognition
Not a main feature but can be useful. Needs training to recognise the user's voice but dictated notes can be recorded as written text. Voice commands and menu navigation can be executed when using applications in a hands-free environment

Language support
Any or all of the following languages are supported: English, German, French, Japanese, Chinese and Korean. Other languages will become available over time.

Steps in the pen's lineage
Grid Systems launches a bulky portable Gridpad system
1991 Go Corporation receives much media coverage for its Penpoint operating system. Microsoft, fearing it would lose out, rushes out Pen Computing for Windows, an add-on to Windows 3.1. Microsoft fought as only it knows how to prove that its pen technology was the best but Go managed to maintain the high ground for a while
1993 Go is bought by AT&T, renamed EO and ultimately sinks without trace. Similarly, Microsoft's dreadful Pen Computing initiative goes underground and is removed from the market. The Apple Newton is launched as a personal digital assistant (PDA) - but a fairly bulky one. Early models gave handwriting recognition a bad name
1997 The year the PDA really comes of age with the launch of the US Robotics Pilot which is extremely successful. After a buyout of the mother company by 3Com, the handheld system is spun-off as Palm. This popularised handwriting recognition
2001 IBM launches the Thinkpad Transnote following an abortive attempt to launch the Crosspad in 1997. Transnote fairs no better
2002 Apple releases OS X update (10.2) featuring Inkwell handwriting recognition with little hardware support or public attention. Microsoft launches the Tablet PC operating system and numerous partners produce hardware around it.

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