Page 177 - Handbook of Electronic Assistive Technology

Chapter 6 • Environmental Control 165

Second Generation Systems – ‘Hardwired Fixed Installation Systems’
in the Home: 1980s
The advent of microprocessor technology and portable computers brought a new means
to implement EC (Fig. 6-9). These systems consisted of a central processor unit and con-
trol unit, with a console for display of the scanning menu. The console was often mounted
on a wall due to its size. Operation of the EC functions was via direct electrical connec-
tion to the peripheral control units through electrical cabling, the network of which often
extend throughout the home. The installation of the system was therefore a considerable
effort in time and materials and meant that it was unsuitable for short-term needs.

Third Generation – Remote Transmission, Portable Controller Systems: 1990s
Further technological development brought low-power consumption electronics and
integrated microcontrollers, incorporating all aspects of digital control into a single inte-
grated circuit. These permitted portable controllers that could be taken with the user
around the home, using internal rechargeable batteries and onboard signal transmitters
for the remote control of the end appliances. This avoided the need for extensive cabling
throughout the home, but introduced new issues of battery endurance, standby power
saving and remote signal reception. Some of the processing and control functioning of
the system became distributed to the more autonomous and discrete peripheral interface
units, which were now powered separately. Although some definition of the requirements

FIGURE 6-9 Historic EC systems: Possum PSU6�