APM 1.0 Systems May Not Save and Restore All Hardware States

ID: Q134536

The information in this article applies to:

Microsoft Windows 95

SYMPTOMS

Some system functionality may be lost when you resume from Suspend mode if the following conditions exist:

You activated Suspend mode with a hardware switch (such as a Suspend button on the body of the computer).

An MS-DOS session was active when you suspended the system.

The computer contains an Advanced Power Management (APM) 1.0 BIOS.

For example, if you are playing an MS-DOS-based game with sound when you suspend the system, sound support may not function when the system resumes.

CAUSE

When you suspend the system using a hardware switch, an APM 1.0-compliant BIOS may process the suspend request too quickly for Windows 95 to save the current hardware settings. Without these settings, Windows 95 may not be able to reinitialize all the hardware devices properly when the system resumes.

RESOLUTION

Use the Suspend command on the Start menu to suspend the system, instead of using a hardware switch.

MORE INFORMATION

When a system suspend is requested with a hardware switch, the APM 1.0 BIOS informs the operating system that it is about to suspend the system. APM 1.0 systems do not wait for a response from the operating system but simply wait a predetermined amount of time before suspending the system.

APM 1.1 systems do not have this problem because Windows 95 can request that they wait until the operating system is ready to be suspended.

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