NCR RealPOS 70 - G1 Sleeping; G0 Working

Chapter 1: Product Overview 1-27
G1 Sleeping
Acomputerstatewherethecomputerconsumesasmallamountof
power,usermodethreadsarenotbeingexecuted,andthesystem
appearstobeoff(fromanenduser’sperspective,thedisplayisoff,and
soon).LatencyforreturningtotheWorkingstatevariesonthewake
environmentselected
priortoentryofthisstate(forexample,whether
thesystemshouldanswerphonecalls).Workcanberesumedwithout
rebootingtheOSbecauselargeelementsofsystemcontextaresavedby
thehardwareandtherestbysystemsoftware.Itisnotsafeto
disassemblethemachineinthis
state.
G0 Working
Acomputerstatewherethesystemdispatchesusermode(application)
threadsandtheyexecute.Inthisstate,peripheraldevices(peripherals)
arehavingtheirpowerstatechangeddynamically.Theusercanselect,
throughsomeUI,variousperformance/powercharacteristicsofthe
systemtohavethesoftwareoptimizeforperformanceorbatterylife.
The
systemrespondstoexternaleventsinrealtime.Itisnotsafeto
disassemblethemachineinthisstate.
UndertheG1sleepingstateACPIdefineslevelsofsystemsleepstate
support.The7402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context.
The7402doesnotsupporttheS2,S3(SuspendtoRAM),orS4
(SuspendtoDisk)sleepingstates.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.