COMPUTER
HARD WARE
INPUT DEVICE
Mouse
Keyboard
Scanner
Light
pen
Joystick
OUT PUT DECICE
Monitor
Printer
Plotter
Speaker
Head
phone
STOREG DEVICE
CD/DVD
Floppy
disk
Hard
disk
Mother board
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Motherboard for an Acer desktop
personal computer(PC), showing the typical components and interfaces
that are found on a motherboard. This model was made by Foxconn in 2008, and
follows the ATX
layout (known as the "form factor") usually employed for desktop computers. It is
designed to work with AMD's Athlon 64
processor
A motherboard of a Vaio E series
laptop (right)
In personal computers, a motherboard (sometimes alternatively known as the
mainboard, system board, planar board or, on logic
board[1])
is the central printed circuit board in many modern computers
and holds many of the crucial components of the system, providing connectors
for other peripherals.
Motherboard specifically refers to a printed circuit board with
expansion capability. The term mainboard is applied to devices with a
single board and no additional expansions or capability. In modern terms this
would include controlling boards in televisions, washing machines and other embedded systems.
conects
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History
Prior to the advent of the microprocessor,
a computer was usually built in a card-cage case or mainframe with components connected by a backplane
consisting of a set of slots themselves connected with wires; in very old
designs the wires were discrete connections between card connector pins, but
printed circuit boards soon became the standard practice. The Central Processing Unit, memory and peripherals
were housed on individual printed circuit boards which plugged into the
backplate.
During the late 1980s and 1990s, it
became economical to move an increasing number of peripheral functions onto the
motherboard. In the late 1980s, motherboards began to include single ICs
(called Super I/O chips) capable of supporting a set of low-speed
peripherals: keyboard, mouse, floppy disk drive, serial ports, and parallel ports. By the late 1990s, many personal
computer motherboards supported a full range of audio, video, storage, and
networking functions without the need for any expansion cards
at all; higher-end systems for 3D gaming and computer graphics typically retained only the graphics card as a separate
component.
The early pioneers of motherboard
manufacturing were Micronics, Mylex, AMI, DTK, Hauppauge, Orchid Technology, Elitegroup, DFI, and a number of Taiwan-based manufacturers.
The most popular computers such as
the Apple II
and IBM PC
had published schematic diagrams and other documentation which permitted rapid reverse-engineering and third-party replacement motherboards. Usually intended
for building new computers compatible with the exemplars, many motherboards
offered additional performance or other features and were used to upgrade the
manufacturer's original equipment.
Power supply unit
From Wikipedia, the free
encyclopedia
ATX power supply unit with top cover
removed
For electronic power supplies in
general, not just used in desktop computer devices or computer server
devices, see Power supply.
A power supply unit (PSU)
converts mains AC to low-voltage regulated DC power
for the internal components of a computer. Modern personal computers
universally use a switched-mode
power supply. Some power supplies have a manual
selector for input voltage, while others automatically adapt to the supply
voltage.
Most modern desktop personal
computer power supplies conform to the ATX form factor. ATX
power supplies are turned on and off by a signal from the motherboard.
They also provide a signal to the motherboard to indicate when the DC power
lines are correct so that the computer is able to boot up. While an ATX power
supply is connected to the mains supply it provides a 5 V stand-by (5VSB)
line so that the standby functions on the computer and certain peripherals are
powered. The most recent ATX PSU standard is version 2.31 of mid-2008.
Functions
The desktop computer power supply
changes alternating current from a wall socket to low-voltage direct current to operate
the processor and peripheral devices. Several direct-current voltages are
required, and they must be regulated with some accuracy to provide stable
operation of the computer. A power supply rail or voltage rail
refers to a single voltage provided by a power supply unit (PSU). Although the
term is generally used in electronic engineering, many people, especially computer enthusiasts, encounter it
in the context of personal computer power supplies.
First-generation microcomputer
and home computer power supply units used a heavy step-down transformer
and a linear power supply. Modern computers use switched-mode
power supplies (SMPS) with a ferrite-cored
high frequency transformer. The switched-mode supply is much lighter and
less costly, and is more efficient, than an equivalent linear power supply.
Computer power supplies may have
short circuit protection, overpower (overload) protection, overvoltage
protection, undervoltage protection, overcurrent protection, and over
temperature protection.
Recent power supplies have a standby
voltage available, to allow most of the computer system to be powered off. When
the computer is powered down but the power supply is still on, it can be
started remotely via Wake-on-LAN and Wake-on-ring
or locally via Keyboard Power ON (KBPO) if the motherboard supports it.
Power supplies may have passive or
active power factor correction (PFC). Passive PFC is a simple way of increasing the power factor
by putting a coil in series with the primary filter capacitors. Active PFC is more complex and can achieve higher PF, up
to 99%
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