NCR RealPOS 5953 - Hot Plug Capability; POS-Checkout Keyboard Protocol Comparison

5-4 Chapter 5: 5953 USB DynaKey Migration
Hot Plug
TheNCR5953USBDynaKeyishot‐pluggable.Thatis,boththeDVIand
USBconnectionsmaybedisconnectedandtheDynaKeyreplaced
withoutremovingpowerfromtheterminal.TheWedgeDynaKey
cannotberemovedorreplacedwithoutremovingpowerfromthe
terminal.
POS-Checkout Style Keyboard
ThegreatestdifferencebetweentheNCRWedgeDynaKeyandthe
USBDynaKeyisthecommunicationsbetweenthekeyboardandthe
hostcomputer.TheWedgeDynaKeycommunicatesusingthePS/2
communicationsprotocol,whichisbit‐serialandoperatesat
approximately25Kbps.TheUSBDynaKeyusestheUSB1.1protocol,
whichisa
neweranddifferentbit‐serialprotocolthatoperatesateither
1.5or12Mbps.Thekeyboardoperatesat12Mbps.
Furthermore,eachoftheseprotocolsincludesasoftwarelayer.The
PS/2softwarelayerisverysimplistic,andpresentsachallengewhen
addingadditionalcapabilitiesbeyondthekeyboarditself.Allthe
addeddevices,
suchasMSR,Keylock,tone,andscannerare
implementedaswedgedevices.Thattermmeansthatthesedevicesare
wedgedintothekeyboarddatastreamandmustspooftheirwaypast
theO/Stotransferdata.Thistechnique,thoughwidespread,canhave
problems,andisnotstandardized.
TheUSBsoftwarelayer
isstandardizedandrichlydefined.Itsupports
multiplesimultaneouschannelsofcommunications,andallows
additionalcapabilitiestobeaddedwithoutnegativeimpact.