Configuration Setup utility Historically, the BIOS in the IBM PC and XT had no built-in user interface. The BIOS versions in earlier PCs (XT-class) were not software configurable; instead, users set the options via DIP switches on the motherboard. Later computers, including most IBM-compatibles with 80286 CPUs, had a battery-backed nonvolatile BIOS memory (CMOS RAM chip) that held BIOS settings. These settings, such as video-adapter type, memory size, and hard-disk parameters, could only be configured by running a configuration program from a disk, not built into the ROM. A special "reference diskette" was inserted in an IBM AT to configure settings such as memory size.
confiGUratIon setUp UTIlIty HIStorIcally, thE bIoS in tHe iBm Pc And xT hAd nO BUilt-In USeR interface. The Bios veRSIons In eArLiER pcS (xt-cLaSs) WeRe NOt sOftwARe COnfiguRAble; Instead, usErs Set thE oPTIoNs Via Dip swITchEs oN The MotherBOard. Later cOmPUTErs, IncludIng MoST IBm-comPATibles With 80286 Cpus, had A battERY-baCkeD nonvolATile bioS memoRy (cmOS raM cHip) tHAt helD bios seTtings. thEsE sEtTings, SuCh As viDeo-AdapTEr TypE, mEMory size, AnD haRd-DIsk parameteRs, cOuld only be conFigureD bY ruNnIng a coNfIgurATIon progRaM From a disk, not builT InTO the Rom. a sPEcial "REferEnCe dISkette" Was InSerted in an iBM At to cOnfIguRE sEttiNGs SuCH aS MemorY size.