NCR RealPOS 50 - ACPI Sleep States (S0 - S5)

1-14 Product Overview
ACPI Sleep States (S0 - S5)
UndertheG1sleepingstateACPIdefineslevelsofsystemsleepstatesupport.The
7611supports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system
contexts.
Note: The7611doesnotsupportS1state.Turningoffthebacklightandhard
drivesprovidestheequivalentpowersavings(duetoIntelʹsprocessorC‐states
feature)atnearlyzerolatency.
•S2:Notsupported
•S3(SuspendtoRam):TheS3sleepingstateisalowwakelatency
sleepingstate.
ThisstateissimilartotheS1sleepingstateexceptthattheCPUandsystemcache
contextislost(theOSisresponsibleformaintainingthecachesandCPUcontext).
Controlstartsfromtheprocessorʹsresetvectorafterthewakeevent.InNCR
systems,duringS3,power
isonlyprovidedtotheon‐boardUSB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then
reconnected.Thisdoesnotpresentaproblemandthe USBdeviceswillcontinueto
operate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from
enteringS3state.
• ʺS4(SuspendtoDisk):TheS4stateisthelowestpower,longestwakelatency
sleepingstatesupportedbyACPI.
Inordertoreducepowertoaminimum,itis
assumedthatthe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
•SomeperipheralsmaynotbeS4capable,whichcanpreventthe
systemfrom
enteringS4state.
ReferencetheACPISpecificationfordetails.
Peripherals:ACPIdefinespowerstatesforperipheralswhichareseparatefromthe
systempowerstate.ThedevicepowerstatesrangefromD0(fully‐on)toD3(off)It
istheresponsibilityofthedriverdeveloperforeachperipheraltodefine
and
supporttheavailablepowerstates.