Appendix

A. "The Pad was a prototype pen computer. It was 9x11x1", had a four 4 hour battery life, and weighed 5 pounds. It used a Motorola 683xx processor with 4 MB ram running aunique real-time operating system. The Pad featured a PCMCIA slot, an electronic pen of our own design with a built-in microphone, a 640x480 4 level display, keyboard and serial ports. The Pad could communicate through infrared at 19.2kbs, through a unique nearfield radio at 240kbs, and through a 1Mbs tether which also supplied external power for operation and recharging. A complete Pad system also had a radio basestation that served as arecharging station and Ethernet gateway for the Pads. " --from http://www.ubiq.com/weiser/testbeddevices.htm

B. "The Tab was a prototype handheld computer. It was 2x3x0.5", had a 2 week battery life on rechargeable batteries, and weighed 7 oz. It used a Phillips 8051 processor with128k NVRAM. It featured an external I2C external bus, a custom resistive touch screen, and a 128x64 mono display. A complete Tab system included an infrared basestation in the ceiling for LAN connectivity. The Tab project is consider by many to be the most significant of the three prototyping efforts." --from http://www.ubiq.com/weiser/testbeddevices.htm

C. Audio Aura "PARC's system, Audio Aura, is based on three known technologies: active badges, distributed systems and digital audio delivered via portable wireless headphones. An active badge is a small electronic tag designed to be worn by a person. It repeatedly emits a unique infrared signal and is detected by a low-cost network of IR sensors placed around a building. A location server combines all the information culled from the IR sensors and augments it with other information such as online calendars and email systems. The delivery of audio cues is triggered by changes in the location database. Digitized sound is converted to analog and then sent to the userÕs wireless headphones." -Mynatt

D. The Dangling String "Created by artist Natalie Jeremijenko, the "Dangling String" is an 8 foot piece of plastic spaghetti that hangs from a small electric motor mounted in the ceiling. The motor is electrically connected to a nearby Ethernet cable, so that each bit of information that goes past causes a tiny twitch of the motor. A very busy network causes a madly whirling string with a characteristic noise; a quiet network causes only a small twitch every few seconds. Placed in an unused corner of a hallway, the long string is visible and audible from many offices without being obtrusive." -Weiser

E. Philip Gray's Three Location subdivisions:

1. Viability
   The executability of the task can be conditional on the current location of the user and/or resources/agents. Some tasks may be hindered because of environmental constraints (e.g., pen-based input on a moving vehicle or cellular phone outside of the coverage zone), because of distance (e.g., file transfer time or time zone lag) or because a location may be unknown (e.g., the user wants to contact a colleague who is travelling but s/he doesnÕt know the exact location).
2. Method
   If a task is viable, location may nevertheless constrain the methods available to perform the task. For example, pen-based text input on a moving train is impractical but keyboard text input may be feasible. Cellular phone communication from within a building may prove impossible and may lead the user to prefer a standard phone line. Sending a message to someone may well depend on whether they are at home or in their office.
3. Consequential Subtasks
   Finally, a particular method for performing the task may require the execution of extra tasks as a consequence of location. For example, a user travelling between two countries has to reconfigure the dialling prefix of his/her communication software to access the company file server. Often, but not always, these consequential subtasks are required to enable the successful execution of the main task.20