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2.2.5 Low Consumption Current Process
This terminal has (1) the APM BIOS installed to provide a low-power consumption capability.
It works in combination with POWER.EXE from Microsoft Corporation. The low-power
consumption capability is further enhanced by the use of unique power management functions,
including (2) Auto Power OFF (APO) function, (3) Auto Backlight OFF (ABO) function, and (4)
DOZE/RUN transition function.
Advanced Power Management Process (APM)
The APM process, which is an interface between the hardware and application programs, has been
developed by the Intel Corporation and Microsoft Corporation for power control purposes.
APM consists of four layers. The layers include hardware, APM BIOS, APM Driver, and the
application, as shown below. With respect to the PC card which is a removable device, the APM
functions are provided from the specific APM driver (CS_APM.EXE).
Fig. 2.7
Basically, APM functions in the following two ways:
APM BIOS, which is in the background, controls the power conditions of each device.
Applications can call the APM BIOS functions to obtain or control the power conditions.
An application that uses the APM BIOS function is called an APM-aware Application. If an
application acquires information related to power conditions via the system library (refer to
Chapter 7.6.2 “System Library”), APM BIOS is actually called within the system library.
It is also possible to directly call APM BIOS from applications. For more information refer to
an APM BIOS manual published separately by a third party.
PC Card APM Driver
(CS_APM.EXE)
Applications Layer
APM-aware Applications
OS Layer
BIOS Layer
Hardware Layer
APM Driver (POWER.EXE)
APM BIOS
PC Card (Add-in Device)APM BIOS Controlled Device