Hardware reference guide

Chapter 3: The Software
Power Management
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7535 Hardware Reference Guide
3.3.2.6 Differences
The customized Psion Teklogix shell is an enhanced version of the Handheld PC
(HPC) shell, which is similar to the shell on the desktop version of Windows. There
are some modifications to account for differences between the typical HPC and the
7535’s screen size and requirements. The major differences between the HPC shell
and Psion Teklogix’ shell on the 7535 are:
• The HPC shell is optimized for 480x240 pixel displays, while Psion Tek-
logix’ shell is optimized for both 240x320 and 320x240 displays.
• The HPC shell has a 26-pixel taskbar, Psion Teklogix’ shell reduces this to
18-pixels to maximize the desktop (work) area.
• Psion Teklogix’ shell does not have a start button. Any important links
should be on the desktop.
• Psion Teklogix’ shell does not have tabs on the taskbar for the running
applications.
• Psion Teklogix’ shell uses the Menu key-combination (Blue + 0) to display
a start menu with shortcuts to frequently used features.
3.3.2.7 Error Messages
The shell uses the Windows CE standard error messaging system to display major
errors and uses on screen message boxes to display runtime errors.
3.4 Power Management
The Power Manager acts as a mediator between devices, applications, and defined
OS power states. It implements the following set of rules for facilitating communi-
cation between those three parties:
• OS power states impose maximum power consumption limits on all
devices.
• Applications impose minimum power consumption limits on specific
devices to obtain minimum performance levels.
• The Power Manager allows devices to intelligently manage their own
power as long as they keep their power levels between the maximum and
minimum limits.