Description of Windows for Pen Computing Pens (85663)

SUMMARY

There are two types of pens used in the Windows for Pen operating system: tethered, and untethered. They act similarly in every respect; the only difference is that one is attached to the machine and the other is tethered by a small cable.

Pen input devices must have an installable device driver, similar to a mouse driver, in the SYSTEM.INI file to communicate with the system. There are several distinct differences between mouse and pen drivers:

• Pen drivers must report x,y coordinate location information at much higher resolutions than mice. Pens must record at least 120 events per second and have a resolution of at least 200 spots per inch. Pen data is reported to the Pen device driver (PENWIN.DLL) at .0001 inch resolution. Though this resolution is not fully used at this time, it allows for subsequent improvements in pen hardware.
• Pen drivers may also report pressure, angle of rotation, or other pen state information.
• Pen drivers use a private interface to manage the high data rate, thus avoiding a large amount of useless information.

In addition to the differences above, some pen device drivers have a feature known as proximity sensing. This detects the x,y coordinate of the pen without actually touching the tablet or screen.

Working in conjunction with the Pen device driver, Windows for Pen also uses a special display driver that communicates with the Pen device driver. This is required to allow a close interaction between the use of the pen and the display of electronic ink on the screen.