NCR RealPOS 5953 - Double-High;Double-Wide Key Customization

5-6 Chapter 5: 5953 USB DynaKey Migration
Double-High / Double-Wide Keys
Withcapablekeysyoucanputcapsoverpairsofplungers,resultingin
largerkeys.Onastandardkeyboard,thespacebar,theEnter,Tab,
Delete,Shift,Control,andAltkeysareallwiderthantherest.Thesekeys
areimplementedwithoneortwoplungers,butthey
cannotbe
modifiedfordifferentfunctionality.OnNCRkeyboards,thecapable
keysmaybecappedinpairs.Keycapsareavailablethatcovertwo
plungers,eitherdouble‐highordouble‐wide.
Whentwokeysarecappedindividually,thekeyboardfirmwaremust
detecteachoneasadifferentkey,andmust
senddifferentmessagesto
thehostcomputertoindicatethatdifferentkeyswerepressed.When
thesametwokeysarecappedtogether,thefirmwaremustknowthis
andsendonlyonemessage.Withthe5953WedgeDynaKey,thisis
accomplishedbyusingfirmwarethatsensesbothplungersandthe
timelag
betweentheplungers.Ifadjacentplungersarepressedwithin
acertaininterval,thenthefirmwareonlysendsoneofthetwo.Which
oneitsendsisfixed,andthetimelagisfixed.Thus,althoughthis
methodworks,itissubjecttooccasionalerrorduetosmallmechanical
toleranceproblems.
Itisalsosomewhatlimitedinflexibility.
Withthe5953USBDynaKey,thekeyboardisfullyprogrammable.Two
keysthatarecappedtogethercanbeprogrammedtoliterallybe
the
samekey.(Duplicatemessagesarediscarded.)Thusthereisnolimitto
theflexibility,andnoproblemcanbeinducedbythesameminor
mechanicalproblemsexperiencedwiththe5953WedgeDynaKey.