NCR 7454 - Pentium III;Celeron Default BIOS Settings

6-6 Chapter 6: NCR 7454 4x20 Customer Display
Command Descriptions
Structure/Logic Description
TheRetailVFDfirmwareiscomprisedofoperatingsystemtype
servicessuchascommonsubroutines,interruptserviceroutines,and
dataprocessingroutines.Normally,thefirmwareisalwaysactive
refreshingtheRetailVFDtokeepdisplaydatavisible.Thefirmware
willalsoactoninterruptsduetohostparallelcommunication.This
communication
isintheformofcommandsfromthehosttotheRetail
VFDthatrequiretheRetailVFD tomodifythedisplayappearance.
TheRetailVFDfirmwareusesamicro‐controllerandinterfacesto
parallellinks.
Host/Retail VFD Command Interface
TheRetailVFDacceptstwotypesofdata;displaydataandcommand
data.IfabytereceivedfromthehostisanycharacterexceptESC(0x1B)
character,itisprocessedasacharacteranddisplayedontheRetail
VFD.IfanESCcharacter(0x1B)isreceived,thesubseq uentbyte(s)is
processed
asacommand.Ifthesubsequentbyteisaninvalid
commanditwillbeignored.IfanESCisreceived, butnosubsequent
byteisreceivedwithintenseconds,thefirmwarewillignoreit.
Notethateachcommandconsistsofatleasttwobytes.Thefirstbyte
(0x1B)isa
commandidentifierindicatingthenextbyte(s)isa
commandbyte.Thecommandbytemaybefollowedbyparameteror
databytesdependingonthecommand.Itisonlyvalidtoreceivean
ESC(0x1B)asacommandidentifier.
ThefollowingtabledescribesthesupportedRetailVFDcommands.