This document provides information about computer motherboards. It discusses how a motherboard connects the central components of a computer system and provides slots for expansion cards. Key components of a motherboard include the CPU socket, memory slots, chipset, BIOS, and connectors for power and peripherals. Modern motherboards increasingly integrate functions like audio and storage that used to require expansion cards. The document provides an overview of the purpose and evolution of computer motherboards.
1. Computer Basics
Equipment (Hardware)
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Grade Level Requirements
COMPUTER A machine that processes information and performs
computations.
Tower or The "box" or case that holds
Desktop the parts that make up a
computer: CPU, hard disk
drive, floppy drive, memory
chips, power supply, interface
cards, etc. Click here to learn
more.
CPU Central Processing Unit, or "brains" of the computer
Monitor An output display device (looks
similar to a TV) in a computer
system. You see information
on the monitor's screen.
Screen The viewing area on a monitor or the information or image
displayed.
A device that reads data from (input) or records data onto
Disk Drive
a disk for storage (output).
Floppy
.
Floppy Drive 3-1/2" Floppy Disk
Hard Drive The main device that a computer uses to store
information. Most computers come with a hard drive,
called drive C, located inside the computer case.
2. CD-ROM ROM means Read-Only-Memory - you can only "read"
information, not save.
A CD can store a large amount of data including
documents, photographs, software, and music (about 20
songs)
CD Drive Compact Disk
CD-R
CD-RW
A CD-Recordable drive can put
A CD-ReWritable drive
data onto a disk in just one
can be written onto more
session, and then is "closed" -
than once - similar to a
one "burn" only - you can't add
floppy or hard disk.
to it after you create it.
DVD-ROM
Used to store full-length
Digital Video Disk - Read-Only
movies, large programs,
Memory
etc.
CD's, CD-R's, CD-RW's, and DVD's all look the same.
You must read the label to determine what type of media it is.
Both CD's and DVD's are optical storage media. Optical technology uses
a laser or light beam to process information.
USB Flash These can hold documents,
Drive picures, and music. Some
flash drives are also MP3
players.
Mouse A hand-held input device you roll on your desk to point to
and select items on your screen. When you move the
mouse, the mouse pointer on the screen moves in the same
direction.
3. Mouse The little symbol on your screen that you move with your
pointer mouse. You use the mouse pointer to point to and select
items on your screen. The mouse pointer changes shape,
depending on its location on your screen and the action you
are performing.
Left Mouse Button - usually use this button
Right Mouse Button - occasionally use this button for
"special" actions
Scroll Wheel - the mouse wheel may work differently
from program to program. and it may not work in some
programs. In most word processing programs, you can
rotate the wheel to move up or down the page, equivalent
to using the PAGE UP or PAGE DOWN keys on your
keyboard or to clicking the scroll bar. Due to various
problems it is best if you do not use the scroll wheel in
the computer lab.
Click Press and quickly release the button on a mouse
Double Press and quickly release the mouse button twice.
Click
Drag
Move objects or data around on the screen through the
use of a mouse. Keep the left mouse button pressed while
you move the mouse.
Speakers Output device that produces
sound and music when
connected to the
computer. Speakers come in
different shapes and may even
be in the monitor's case.
4. Headphones
Output device for listening
that is held over the ears by a
band worn on the head
Microphone
Input device in which sound
energy is changed into
electrical energy for the
sending or recording sound
(your voice).
Scanner
Input device that reads copy
as an image and digitally
records the image
Digital Records and stores images as a
Camera digital file, operates similarly
to a "normal" camera, but no
"film" is needed
Projector Output device for displaying
onto a large surface
(projection screen) what
appears on the computer
monitor.
Printer
A device that produces a paper copy of the information on
your screen. The printer on the left is an INK JET
PRINTER, and the other is a LASER PRINTER.
.
.
5. Hub
Hubs are devices that have many ports into which network
cables are plugged. A hub takes the signal from each
computer and sends it to all of the other computers
through the network. Hubs come in different sizes and
colors. The hub must be plugged in and turned on for the
network to work - be sure you see green lights
Modem A device that allows computers to communicate with each
other over telephone lines (Internet). At school we do not
use modems, we have a direct connection to the Internet
called a T-1 line.
Keyboard Input device - choose letters, symbols, and actions by
pressing keys
Key Any of the buttons on a keyboard that the user presses to
input data (information) or to type commands
Escape Usually pressed while you are working in a software
application to stop the current activity, back out of a
menu (or screen), or return to a previous screen.
Enter Used to move the cursor to the beginning of a new line. It
may also be called the return key. In some applications,
pressing Enter tells the computer to stop waiting for more
input and begin processing. Notice the arrow symbol on
the Enter key; it is sometimes used in instructions and
means to press the enter key.
Backspace Moves the cursor one space to the left, erasing any
character that is in its path
6. Spacebar Moves the cursor one space to If the spacebar is "split",
(split the right, leaving a small blank the left "spacebar" acts
spacebar) white area (space) on the like the backspace key - it
screen. erases the character to
the left of the cursor.
shift Does nothing by itself, but when pressed and held down
with another key it makes either a capital letter or the
upper character on a key. Pressing Shift with a letter key
when the CAPS LOCK key is "on" makes a lower case
letter.
caps lock Makes all letters uppercase without having to use the
shift key - it is best to only use this when you are going to
make many letters uppercase - don't use for just a few
capital letters
tab Marked with two arrows, one pointing left, the other,
right. If pressed by itself, it moves the cursor to the
next tab on the right. When pressed with the Shift key,
it moves the cursor to the previous tab stop on the left.
alt Does nothing by itself. When pressed with another key, it
performs a special function. For example, pressing Alt-F4
may quit a currently running program.
ctrl Does nothing by itself. When pressed with another key, it
performs a special function. For example, pressing Ctrl-S
may "save" a document.
Num Lock Typically "on" at start up. When "on", it changes the keys
on the numeric keyboard from cursor control arrows to
numbers arranged in a typical ten-key calculator keypad.
Delete On our "Windows" computers (P) it erases the character
to the right of the cursor. Some people say it performs a
"forward erase". It operates differently on a MAC.
End The key you press to move the cursor to the end of the
current line. Many programs also use keyboard shortcuts
such as Ctrl+End to move the cursor to the end of a
document.
7. Insert Changes between insert mode and overstrike mode in word
processing programs. In insert mode, all characters typed
are placed at the cursor position (or to the right of the
insertion point). As you type, anything to the right of the
cursor moves to the right to make room for the new
typing. If insert mode is turned off, typing then
overwrites (erases) the old characters instead of putting
the new ones before the old ones. This is often called
overwrite mode. Most PC keyboards have an Ins or Insert
key that lets you switch back and forth between insert
and overwrite modes. Many word processing programs
display OVR in a status bar at the bottom when overwrite
mode is on.
Home The key you press to move
the cursor to the
beginning of the current
line. Many programs also
use keyboard shortcuts
such as Ctrl+Home to move
the cursor to the
beginning of a document.
PgDn The function of this key is usually software
specific. Typically, it scrolls a document backward one
screen or one page.
PgUp The function of this key is usually software
specific. Typically it scrolls a document forward one
screen or one page.
Arrows 4 keys that move the cursor in the direction the arrow
points
Function
Keys Special keys that perform a number of important
(F1, F2 tasks. Their exact functions are software dependent. F1
...) usually is reserved for Help, while F10 frequently exits or
quits the program.
Print Screen It directs the computer to copy whatever is displayed on
the screen to the clipboard for pasting later. It doesn't
really "print" in Windows.
8. Scroll Lock Its function is often software specific. In spreadsheets,
it usually locks the cursor on its current screen line and
scrolls text (rather than the cursor) up or down whenever
an up or down cursor control arrow is pressed.
Pause Not usually used with Windows. Pressing this key under
DOS temporarily stops a screen display or freezes rapidly
scrolling information.
Windows Key The WINDOWS key acts as another special function key.
If you press the Window key by itself, the Start
Menu will open. Windows+E will launch Windows Explorer.
Click here to learn more about the Windows keyboard.
Learn more about Computer Basics.
Skills Needed
4th, 5th, and 6th Graders
Know the above terms
Basic mouse functions - moving on pad, execute buttons
Understand keyboard: Esc, Enter, cursor keys, insert, delete,
space, shift, caps
Understand function keys, Num Lock, tab, alt, PgDn, PgUp, Ctrl
Return to Student Resource Pages
Last updated June 23, 2011 ~ Mrs. K. Bradley
kbradley@otsegoknights.org
9. Motherboard
From Wikipedia, the free encyclopedia
Jump to: navigation, search
In personal computers, a motherboard is the central printed circuit board (PCB) in many
modern computers and holds many of the crucial components of the system, providing
connectors for other peripherals. The motherboard is sometimes alternatively known as the
mainboard, system board, planar board or, on Apple computers, the logic board.[1] It is
also sometimes casually shortened to mobo.
Motherboard for an Acer desktop personal computer, 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.
10. A motherboard of a Vaio E series laptop (right)
Contents
[hide]
1 History
2 Overview
o 2.1 CPU sockets
o 2.2 Integrated peripherals
o 2.3 Peripheral card slots
o 2.4 Temperature and reliability
o 2.5 Form factor
3 Bootstrapping using the BIOS
4 See also
5 References
6 External links
[edit] 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 (see below). 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,
11. and parallel ports. As of 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
The term mainboard is applied to devices with a single board and no additional expansions or
capability. In modern terms this would include embedded systems and controlling boards in
televisions, washing machines, etc. A motherboard specifically refers to a printed circuit
board with expansion capability.
[edit] Overview
A motherboard, like a backplane, provides the electrical connections by which the other
components of the system communicate, but unlike a backplane, it also connects the central
processing unit and hosts other subsystems and devices.
A typical desktop computer has its microprocessor, main memory, and other essential
components connected to the motherboard. Other components such as external storage,
controllers for video display and sound, and peripheral devices may be attached to the
motherboard as plug-in cards or via cables, although in modern computers it is increasingly
common to integrate some of these peripherals into the motherboard itself.
An important component of a motherboard is the microprocessor's supporting chipset, which
provides the supporting interfaces between the CPU and the various buses and external
components. This chipset determines, to an extent, the features and capabilities of the
motherboard.
Modern motherboards include, at a minimum:
sockets (or slots) in which one or more microprocessors may be installed[2]
slots into which the system's main memory is to be installed (typically in the form of
DIMM modules containing DRAM chips)
a chipset which forms an interface between the CPU's front-side bus, main memory,
and peripheral buses
non-volatile memory chips (usually Flash ROM in modern motherboards) containing
the system's firmware or BIOS
a clock generator which produces the system clock signal to synchronize the various
components
12. slots for expansion cards (these interface to the system via the buses supported by the
chipset)
power connectors, which receive electrical power from the computer power supply
and distribute it to the CPU, chipset, main memory, and expansion cards.[3]
The Octek Jaguar V motherboard from 1993.[4] This board has few onboard peripherals, as
evidenced by the 6 slots provided for ISA cards and the lack of other built-in external
interface connectors.
Additionally, nearly all motherboards include logic and connectors to support commonly
used input devices, such as PS/2 connectors for a mouse and keyboard. Early personal
computers such as the Apple II or IBM PC included only this minimal peripheral support on
the motherboard. Occasionally video interface hardware was also integrated into the
motherboard; for example, on the Apple II and rarely on IBM-compatible computers such as
the IBM PC Jr. Additional peripherals such as disk controllers and serial ports were provided
as expansion cards.
Given the high thermal design power of high-speed computer CPUs and components, modern
motherboards nearly always include heat sinks and mounting points for fans to dissipate
excess heat.
[edit] CPU sockets
Main article: CPU socket
A CPU socket or slot is an electrical component that attaches to a printed circuit board (PCB)
and is designed to house a CPU (also called a microprocessor). It is a special type of
integrated circuit socket designed for very high pin counts. A CPU socket provides many
functions, including a physical structure to support the CPU, support for a heat sink,
facilitating replacement (as well as reducing cost), and most importantly, forming an
electrical interface both with the CPU and the PCB. CPU sockets on the motherboard can
most often be found in most desktop and server computers (laptops typically use surface
mount CPUs), particularly those based on the Intel x86 architecture. A CPU socket type and
motherboard chipset must support the CPU series and speed.
[edit] Integrated peripherals
13. Block diagram of a modern motherboard, which supports many on-board peripheral functions
as well as several expansion slots.
With the steadily declining costs and size of integrated circuits, it is now possible to include
support for many peripherals on the motherboard. By combining many functions on one
PCB, the physical size and total cost of the system may be reduced; highly integrated
motherboards are thus especially popular in small form factor and budget computers.
For example, the ECS RS485M-M,[5] a typical modern budget motherboard for computers
based on AMD processors, has on-board support for a very large range of peripherals:
disk controllers for a floppy disk drive, up to 2 PATA drives, and up to 6 SATA
drives (including RAID 0/1 support)
integrated graphics controller supporting 2D and 3D graphics, with VGA and TV
output
integrated sound card supporting 8-channel (7.1) audio and S/PDIF output
Fast Ethernet network controller for 10/100 Mbit networking
USB 2.0 controller supporting up to 12 USB ports
IrDA controller for infrared data communication (e.g. with an IrDA-enabled cellular
phone or printer)
temperature, voltage, and fan-speed sensors that allow software to monitor the health
of computer components
Expansion cards to support all of these functions would have cost hundreds of dollars even a
decade ago; however, as of April 2007 such highly integrated motherboards are available for
as little as $30 in the US.
14. [edit] Peripheral card slots
A typical motherboard of 2009 will have a different number of connections depending on its
standard.
A standard ATX motherboard will typically have one PCI-E 16x connection for a graphics
card, two conventional PCI slots for various expansion cards, and one PCI-E 1x (which will
eventually supersede PCI). A standard EATX motherboard will have one PCI-E 16x
connection for a graphics card, and a varying number of PCI and PCI-E 1x slots. It can
sometimes also have a PCI-E 4x slot. (This varies between brands and models.)
Some motherboards have two PCI-E 16x slots, to allow more than 2 monitors without special
hardware, or use a special graphics technology called SLI (for Nvidia) and Crossfire (for
ATI). These allow 2 graphics cards to be linked together, to allow better performance in
intensive graphical computing tasks, such as gaming,video editing etc.
As of 2007, virtually all motherboards come with at least four USB ports on the rear, with at
least 2 connections on the board internally for wiring additional front ports that may be built
into the computer's case. Ethernet is also included. This is a standard networking cable for
connecting the computer to a network or a modem. A sound chip is always included on the
motherboard, to allow sound output without the need for any extra components. This allows
computers to be far more multimedia-based than before. Some motherboards contain video
outputs on the back panel for integrated graphics solutions (either embedded in the
motherboard, or combined with the microprocessor, such as the Intel HD Graphics). A
separate card may still be used.
[edit] Temperature and reliability
Main article: Computer cooling
Motherboards are generally air cooled with heat sinks often mounted on larger chips, such as
the Northbridge, in modern motherboards. Insufficient or improper cooling can cause damage
to the internal components of the computer and cause it to crash. Passive cooling, or a single
fan mounted on the power supply, was sufficient for many desktop computer CPUs until the
late 1990s; since then, most have required CPU fans mounted on their heat sinks, due to
rising clock speeds and power consumption. Most motherboards have connectors for
additional case fans as well. Newer motherboards have integrated temperature sensors to
detect motherboard and CPU temperatures, and controllable fan connectors which the BIOS
or operating system can use to regulate fan speed. Some computers (which typically have
high-performance microprocessors, large amounts of RAM, and high-performance video
cards) use a water-cooling system instead of many fans.
Some small form factor computers and home theater PCs designed for quiet and energy-
efficient operation boast fan-less designs. This typically requires the use of a low-power
CPU, as well as careful layout of the motherboard and other components to allow for heat
sink placement.
A 2003 study[6] found that some spurious computer crashes and general reliability issues,
ranging from screen image distortions to I/O read/write errors, can be attributed not to
15. software or peripheral hardware but to aging capacitors on PC motherboards. Ultimately this
was shown to be the result of a faulty electrolyte formulation.[7]
A microATX motherboard with some faulty capacitors.
For more information on premature capacitor failure on PC motherboards, see
capacitor plague.
Motherboards use electrolytic capacitors to filter the DC power distributed around the board.
These capacitors age at a temperature-dependent rate, as their water based electrolytes slowly
evaporate. This can lead to loss of capacitance and subsequent motherboard malfunctions due
to voltage instabilities. While most capacitors are rated for 2000 hours of operation at 105
°C,[8] their expected design life roughly doubles for every 10 °C below this. At 45 °C a
lifetime of 15 years can be expected. This appears reasonable for a computer motherboard.
However, many manufacturers have delivered substandard capacitors,[9] which significantly
reduce life expectancy. Inadequate case cooling and elevated temperatures easily exacerbate
this problem. It is possible, but tedious and time-consuming, to find and replace failed
capacitors on PC motherboards.
[edit] Form factor
Main article: Comparison of computer form factors
Motherboards are produced in a variety of sizes and shapes called computer form factor,
some of which are specific to individual computer manufacturers. However, the
motherboards used in IBM-compatible systems are designed to fit various case sizes. As of
2007, most desktop computer motherboards use one of these[which?] standard form factors—
even those found in Macintosh and Sun computers, which have not been built from
commodity components. A case's motherboard and PSU form factor must all match, though
some smaller form factor motherboards of the same family will fit larger cases. For example,
an ATX case will usually accommodate a microATX motherboard.
Laptop computers generally use highly integrated, miniaturized and customized
motherboards. This is one of the reasons that laptop computers are difficult to upgrade and
expensive to repair. Often the failure of one laptop component requires the replacement of the
entire motherboard, which is usually more expensive than a desktop motherboard due to the
large number of integrated components.