BIOS

• Although every personal computer user the same essential sub-assemblies; Each submissively is designed a bit differently.Variations in hardware make it difficult to use a single stranded operating system in stead of tailoring an operating system and applications to specifies computers. A basic input output system (BIOS) is added on ROM IC's provided an interface between the raw PC hardware and the standardized operating system BIOS gives an OS access to a stranded set of function. 

• The firmware in ROM contains programs witch initialize various LSI chips for performing input output operations. These routines can be accessed by any operating system or utilities when ever an I/O operation has to be performed. This relives the OS and utility program from the complex takes of dealing with the input/output controllers.