BIOS: All computer hardware has to work with software through an interface. The BIOS gives the computer a little built-in starter kit to run the rest of softwares from floppy disks (FDD) and hard disks (HDD). The BIOS is responsible for booting the computer by providing a basic set of instructions. It performs all the tasks that need to be done at start-up time: POST (Power-On Self Test, booting an operating system from FDD or HDD). Furthermore, it provides an interface to the underlying hardware for the operating system in the form of a library of interrupt handlers. For instance, each time a key is pressed, the CPU (Central Processing Unit) perform an interrupt to read that key. This is similar for other input/output devices (Serial and parallel ports, video cards, sound cards, hard disk controllers, etc...). Some older PC's cannot co-operate with all the modern hardware because their BIOS doesn't support that hardware. The operating system cannot call a BIOS routine to use it; this problem can be solved by replacing your BIOS with an newer one, that does support your new hardware, or by installing a device driver for the hardware.

See Also : CMOS

Setup

Setup is the set of procedures enabling the configure a computer according to its hardware caracteristics. It allows you to change the parameters with which the BIOS configures your chipset. The original IBM PC was configured by means of DIP switches buried on the motherboard. Setting PC and XT DIP switches properly was something of an arcane art. DIP switches/jumpers are still used for memory configuration and clock speed selection. When the PC-AT was introduced, it included a battery powered CMOS memory which contained configuration information. CMOS was originally set by a program on the Diagnostic Disk, however later clones incorporated routines in the BIOS which allowed the CMOS to be (re)configured if certain magic keystrokes were used.

Unfortunately as the chipsets controlling modern CPUs have become more complex, the variety of parameters specifiable in SETUP has grown. Moreover, there has been little standardization of terminology between the half dozen BIOS vendors, three dozen chipset makers and large number of motherboard vendors. Complaints about poor motherboard documentation of SETUP parameters are very common.

To exacerbate matters, some parameters are defined by BIOS vendors, others bychipset designers, others by motherboard designers, and others by various combinations of the above. Parameters intended for use in Design and Development, are intermixed with parameters intended to be adjusted by technicians -- who are frequently just as baffled by this stuff as everyone else is. No one person or organization seems to understand all the parameters available for any given SETUP.