Tablet device exists long time ago, prior to the mouse. It comes with two parts in general, a sensor plate and a signal source piece. Originally its function was similar to a mouse, a pointing device. User places the signal piece at a location then click a bottom to tell the sensor to register this location. The reaction of this motion, is based on the software application. Due to its cost was too high, its sensor plate size was too big, its primary usage was in the industry for computer-aided-design (CAD) and graphic related applications.

The tablet device sends absolute coordinates of a cursor position to the system. This is different from a mouse that sends relative cursor movements from the current position to the system. Sometimes people feel a bit of frustration of using a mouse if they can not see where the cursor is now. While using a tablet device, you place the cursor at any location without paying an attention the current location is at.

In year 2002 November, Microsoft Corp. launches their Windows® XP Tablet Edition operation system for those Tablet PCs. The Tablet PC integrates a tablet device underneath the LCD display and emphasizes its handwriting features. Since then, the tablet device has changed its meaning from a pointing device into a handwriting device, or a pen device. The tablet signal piece has changed its mouse-like shape into a pen-like shape.

The tablet pen has two popular technologies in the market:

1) Radio Frequency (RF) transmitter technology  - needing a battery to power up, has switches for the writing pressure measurement, left-click, right-click and double left-click.
2) Electro Magnetic Resonance (EMR) technology - needing no battery but gets the energy from the sensor plate, has switches for the writing pressure measurement, and eraser.

The writing pressure measurement introduces the ink effect. Higher writing pressure gets darker and wider stroke. Lighter writing pressure gets dimmer and narrower stroke. Some of graphic applications provide the tools of pen and brush to distinguish having or not-having the ink effectiveness. The interface of a tablet device may be via Universal Serial Bus (USB) port, serial communication (COM) port, or others. There is only one system cursor, a system-level device resource, that is driven by all kinds of pointing, writing, inking, padding, touching devices. All devices are working concurrently.

Ink effect is needed for a artist job, and the stroke looks real. The device without pressure sensitive  will also work on the pen or brush tool of the applications. The usefulness is based upon your applications. The tablet device shall have many more applications than just for art.

The most of people first time of thinking a handwriting or a tablet device would think it for an input device. This is because of the Personal Digital Assistant (PDA), or a Tablet PC does need a pen or stylus as its input device. However, handwriting is not necessary imply to the handwriting recognition. Handwriting serves the purpose of commenting, annotation, teaching, and sharing ideas. While handwriting recognition captures the written image and converts it into text form. Handwriting recognition is needed only when there is no keyboard available, or people can not type.

There are many applications, such as Microsoft PowerPoint®, NetMeeting®, MSN Messenger 7.0, BitWare® (a popular modem bundled software from Computer Associates) have pen features which are just for writing, not for the handwriting recognition. The purpose we try to clarify here is to make  people aware that you need a handwriting device in general, not because of replacing your keyboard or mouse. The handwriting device can be a pen tablet, or a WriteScreen® Tablet monitor.

Before you making a decision which handwriting device to buy, here are the thoughts:

Tablet PC: it is a small size laptop computer. Uses less power but still lasting for only about 4 hours or less per battery charge. Has slower speed CPU, smaller LCD display but still costs much higher than a normal laptop/notebook computer with faster CPU and bigger LCD display. It is designed for mobility, not for office work!
Pen Tablet Pad: it is a low cost solution, good for carry, handwriting, annotation and drawing. However, in the real-time teaching, after marking two points, the task to draw a connection line between these two points can be a difficult thing to do. This is because the pad size in general is smaller than the display screen size. Viewing the display and not watching the hand will make you mentally not easy to coordinate, or not easy to aim the line to end to the destination point. Handwriting will be no problem because all the hand movements are continuously and within a neighborhood area.
Pen Tablet Monitor: it is good for all pen related tasks because the viewing screen and the handwriting motion are correlated.