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BIOS

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BIOS (Basic Input Output System) Bios or the basic input output system is a set of programs stored inside a PROM chip and put on the motherboard. The main job of the program stored into this ROM is, as its name suggests is to provide the computer user the set of standard routines, to take care of input/output from the front input, output and the storage devices connected to the computer. This BIOS ROM is always available in the computer. So any user program can access these routines for their input/output requirements. The first PC BIOS was made by IBM for their PC range of computers. A PC system can be described as a series of layers-some hardware and some software-that interface with each other. Figure shows the four layers in a typical PC. The purpose of the layered design is to enable a given operating system and applications to run on different hardware. Fig shows how two different machines with different hardware can each use different sets of drivers (BIOS) to interf

System Bus Types, Functions, and Features

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                                    System Bus Types, Functions, and Features The heart of any motherboard is the various buses that carry signals between the components. A bus is a common pathway across which data can travel within a computer. This pathway is used for communication and can be established between two or more computer elements. The PC has a hierarchy of different buses. Most modern PCs have at least three buses; some have four or more. They are hierarchical because each slower bus is connected to the faster one above it. Each device in the system is connected to one of the buses, and some devices (primarily chipset) act as bridges between the various buses. The Processor Bus (Front-side Bus) The processor bus (also called the front-side bus or FSB) is the communication pathway between the CPU and motherboard chipset-more specifically the North Bridge or Memory Controller Hub. This bus runs at the full motherboard speed- typically between 66 MHz and 800MHz in mo

Motherboard form factor

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The form factors refers to the physical dimensions (size and shape) as well as certain connector, screw hole, and other positions that dictate into which type of case the board will fit. The more commonly PC motherboard form factors include the following 1  PC and XT The first popular PC motherboard was the original IBM PC released in August 1981. Fig. shows how this board looked. IBM followed the PC with the XT (eXtended Technology) motherboard in March 1983, which had the same size and shape as the PC board but had eight slots instead of five. Both the IBM PC and XT motherboards were 9”×13” in size. The XT also eliminated the little used cassette port in the back. 2  Full size AT (Advanced Technology) This board was 12”×13.8” in size. To accommodate the 16 bit 286 processor and all the necessary support component at the time, IBM needed more room than the original PC/XT size boards could provide. So for the AT, IBM increased the size of the motherboard but reta