NCR 7772 Series User Manual

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NCR 7772 Series User Manual Manual pdf 79 page image

6-67 Power ManagementG0 WorkingA computer state where the system dispatches user mode (application) threads and theyexecute. In this state, peripheral devices (peripherals) are having their power statechanged dynamically. The user can select, through some UI, variousperformance/power characteristics of the system to have the software optimize forperformance or battery life. The system responds to external events in real time. It is notsafe to disassemble the machine in this state.ACPI Sleep States (S0 - S5)Under the G1 sleeping state ACPI defines levels of system sleep state support. The CX7supports the following sleeping states:• S0: Normal Powered-On state• S1 (Standby): The S1 sleeping state is a low wake latency sleeping state. In this state,no system context is lost (CPU or chip set) and hardware maintains all systemcontexts.Note: The CX7 does not support S1 state. Turning off the backlight and hard drivesprovides the equivalent power savings (due to Intel's processor C-states feature) atnearly zero latency.• S2: Not supported• S3 (Suspend to Ram): The S3 sleeping state is a low wake latency sleeping state. Thisstate is similar to the S1 sleeping state except that the CPU and system cache contextis lost (the OS is responsible for maintaining the caches and CPU context). Controlstarts from the processor's reset vector after the wake event. In NCR systems, duringS3, power is only provided to the USB 3.0 ports.Note: When the terminal resumes from an S3 state, all the USB devices re-enumerate. This causes speaker tones as if they were disconnected and thenreconnected. This does not present a problem and the USB devices will continue tooperate correctly.Requirements for S3 support:• O/S must be built on a system with S3 enabled in the BIOS• Some peripherals may not be S3 capable, which can prevent the system fromentering S3 state.• S4 (Suspend to Disk): The S4 state is the lowest power, longest wake latency sleepingstate supported by ACPI. In order to reduce power to a minimum, it is assumed thatthe hardware platform has powered off all devices. Platform context is maintained.Requirements for S4 support:• O/S must be built on a system with S3 enabled in the BIOS