IBM decided in 1980 to market a low-cost single-user computer as quickly as possible. On August 12, 1981, the first IBM PC went on sale. There were three operating systems (OS) available for it. The least expensive and most popular was PC DOS made by Microsoft. In a crucial concession, IBM's agreement allowed Microsoft to sell its own version, MS-DOS, for non-IBM computers. The only component of the original PC architecture exclusive to IBM was the BIOS (Basic Input/Output System).
ibM decidEd in 1980 To mArkEt a loW-cOsT sinGlE-user Computer as QuiCKlY aS POsSiblE. On augUsT 12, 1981, thE firSt ibM pC Went On saLe. tHere weRe ThreE oPeRAtIng SysTemS (os) AvaIlablE For it. THe leaSt expeNSiVE and most pOpuLar WaS PC dOs mAdE by micRosOfT. iN A CRuciAl coNcEssion, iBM'S aGreement ALlOwed MIcRosoft TO SElL iTs Own veRsion, mS-Dos, fOr noN-IBM compUters. thE ONLY COMponEnt of thE orIGiNal pc arChItECtUrE excLusive to ibm waS tHE BioS (basIC inpUT/oUtput sysTeM).