Gridpad

The GRiDPad measures 9 x 12 x 1.4 inches and weighed 4.5 pounds. The first tablet sold commerically was the Linus Write-Top. However, the Gridpad was a very popular tablet with the federal government. It's handwriting recognition software led to the Graffiti and PalmPilot.

The main distinguishing aspect was its touch-screen interface with a stylus, a pen-like tool to aid with precision in a touchscreen device. The stylus was able to use hand writing recognition software. The GRiDPad also included these features:

• • 10 MHz 80C86 processor

  • MS-DOS operating system – the popular operating system used by IBM PC-compatible personal computers

  • A monochromatic Color Graphics Adapter (CGA) display resolution of 640x400

  • 256KB or 512KB battery-backed RAM cards

  • 1MB or 2MB of system memory

  • One serial port, two ATA-FLASH slots, and an expansion bus connector

Because of its use for inventory management, the United States Army specified more durable versions of the tablet made out of magnesium that were not sold to the general public. The US Army specially ordered magnesium because it is a strong yet light metal, making it ideal to be used in demanding environments.

According to a patent submitted in 1992 by an engineer at GRiD Systems, the touch screen in the GRiDPad works by magnifying an internal Cartesian plane and calculating the displacement.[5] Further patents by Jeff Hawkins describe flipping the screen orientation between landscape and portrait.