Motherboard
The main components that are installed on the motherboard:
* CPA
* Set of system logic – the chipset, providing a connection to the CPU memory controller and peripheral devices. As a rule, modern set of system logic is based on two VLSI: «North» and «South Bridge».
* North Bridge, System Controller – CPA provides a connection to the nodes, using high-performance tires: RAM, graphics controller.
To connect the CPU to the system controller can be used such FSB-bus, as Hyper-Transport and SCI.
Typically, the controller is connected to the system RAM. In this case, it contains a memory controller. Thus, from the type of application system controller is usually the maximum amount of RAM depends, as well as the capacity of the memory bus of a PC. But now there is a tendency to be embedded directly into the controller RAM CPA (eg, memory controller built into the processor in the AMD K8), which simplifies the function of the system controller.
As a bus to connect the graphic controller on motherboards using modern PCI Express. Previously used general bus (ISA, VLB, PCI) bus and the AGP.
* South Bridge, the peripheral controller – a controller peripheral devices (hard disk, Ethernet, audio), bus controller for connecting peripheral devices (bus PCI, PCI-Express and USB), as well as the controller bus, which connect devices that do not require high capacity (LPC – used to connect the boot ROM, as well as LPC bus is used to connect multikontrollera (English Super I / O) – chips that support «obsolete» low-data interface: serial and parallel interfaces, controller, keyboard and mouse).
As a general rule, north and south bridges are implemented as separate VLSI, but there are odnochipovye solutions. It is a set of system logic determines all the key features of the motherboard, and what devices can connect to it.
* RAM
* Boot ROM – stores the software which is executed immediately after power on. Typically, a boot ROM contains the BIOS, but may include software operating within the EFI.
Classification motherboard form-factor
Form factor motherboard – the standard that defines the size of the motherboard for the PC, place of fastening to the shell, the location of its bus interfaces, I / O port, the CPU socket (if any), and slots for RAM, as well as the type of connector to connect the power supply.
Form Factor (as well as any other standards) is a recommendation. Specification form factor determines the mandatory and optional components. However, the vast majority of producers prefer to comply with the specification, because the price of conformity with existing standards is the compatibility of the motherboard and standardized equipment (peripherals, expansion cards) from other manufacturers.
* Obsolete: Baby-AT; Mini-ATX; full fee AT; LPX.
* Modern: ATH; microATX; Flex-ATH; NLX; WTX, CEB.
* Implemented: Mini-ITX and Nano-ITX; Pico-ITX; BTX, MicroBTX and PicoBTX
There are motherboards that do not correspond to any of the existing form factors (see table). Usually this is due either to the fact that manufactured specialized computer or motherboard manufacturer’s desire to independently produce and other peripherals to it, or inability to use standard components (so-called «brand», such as Apple Computer, Commodore, Silicon Graphics, Hewlett Packard, Compaq increasingly others ignored the standards, in addition to the largest market for distributed manufacturing emerged only in 1987, when many manufacturers have already created their own platform).