Information Technology Reference
Figure 2: (a) Xerox ParcTab (1992) first context-sensitive computer, sporting
a monochromatic display 128x64 pixel and (b) a current PDA,
featuring a colour VGA (240x320 pixel) display.
the mark. To see the first above-threshold product we needed another decade,
with the advent of the first families of Palm Pilot, small, light and focussed
on a few essential tasks (planner, organizer, contacts manager and a few
more) with a single one-button approach to stay in synch with your desktop
applications. For the first time, the computer industry produced a device
better at one task of the traditional approach, the paper-based daily planners.
To make hardware disappear, its use must be transparent to their user.
A slow Wi-Fi connection will end up absorbing our attention away from our
task at hand, as much as low-resolution display renders poorly the perception
of the entire application. In the very last decade, advances in four technology
segments have directly impacted on the development of ubiquitous systems:
wireless networks, increased computing power, increased memory capacity,
and high-resolution displays. The following sections will briefly discuss them
and their relevance to ubiquitous systems.
3.1 Wireless networks
Although slowly at the beginning, wireless networks have advanced at a steady
pace, thanks to the development of both short-range (Bluetooth and Infrared
Data Association (IrDA)) and long-range (HomeRF, Wi-Fi e Wi-Max)
technologies. Today telecommunication infrastructures allows a seamless