Casio IT-2000W Low Consumption Current Process, Advanced Power Management Process APM, APM Bios

2.2.5Low Consumption Current Process

This terminal has 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 Auto Power OFF (APO) function, Auto Backlight OFF (ABO) function, and DOZE/RUN transit 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).

Applications Layer

OS Layer

BIOS Layer

Hardware Layer

APM-aware Applications

APM Driver (POWER.EXE)

APM BIOS

APM BIOS Controlled Device

Fig. 2.7

PC Card APM Driver

(CS_APM.EXE)

PC Card (Add-in Device)

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 8.6.2 “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 the APM BIOS manual.

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