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Computer peripherals
11/22/2014
Computer peripherals
Dr. Mazen Selim 1
Grading
Homework 20%
Midterm Exam 20%
Final Exam 60%
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Textbox
Microsoft
A+ certification
IT professional
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HIE 4th Level
Computer Peripherals
CH1 :Basic Terms & Concepts
Dr. Maze Selim
11/22/2014 4
Chapter1 Basic Terms & Concepts
Covers the basic hardware components that make up
the personal computer.
How the basic computer system communicates and
interacts with the world around it (that is, input,
output, and I/O devices).
introduces the fundamental software components that
work together to control the operation of the system’s
hardware.
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The PC System
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INSIDE THE SYSTEM UNITInternal system unit components.
The components inside the system unit can be
divided into four distinct subunits: A switching power supply
The disk drives.
The system board.
Options adapter cards
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Inside a desktop unit
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Two common form factors for desktop and
tower computers currently exist The ATX specification includes provisions for a software switch that enables
users to turn off the system’s power supply through software.
AT-Style—The older form factor standard derived from PC-XT and PC-AT specifications.
ATX-Style—A newer form factor standard that has been introduced to overcome problems found
in the AT-Style designs.
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System Boards
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Major Components
The major components of interest on a PC system board are
Microprocessor/CPU—The brains of the system. This component
performs mathematical and logical computations .
Primary Memory—The system’s primary memory elements.
RAM—Random Access Memory (RAM) is quick enough to operate
directly with the microprocessor and can be read from and written to as
often as desired. RAM is a volatile type of memory—its contents
disappear when power is removed from the memory.
ROM—Read-Only Memory (ROM) contains the computer’s permanent
startup programs. ROM is nonvolatile—its contents remain with or
without power being applied.
Cache memory—An area of special high-speed RAM reserved for
improving system performance by holding information that the
microprocessor is likely to use. Blocks of often used data are copied into
the cache area to permit faster access times.
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Major Components-Cont.
Expansion slot connectors—Connectors mounted on the system board
into which the edge connectors of adapter cards can be plugged to
achieve system expansion. The connector interfaces the adapter to the
system’s I/O channel and system buses. Therefore, the number of slots
available determines the expansion potential of the system.
Chipset—Microprocessor support ICs that coordinate the operation of
the system.
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Microprocessors
brains of the computer system because it reads, interprets, and executes software
instructions, and it also carries out arithmetic and logical operations for the
system.
The original PC and PC-XT computers were based on the 8/16-bit 8088
microprocessor from Intel. The IBM PC-AT system employed a 16-bit 80286
microprocessor. Since then, Intel has introduced several different
microprocessors for the PC market. These include devices such as the 80386DX
and SX, the 80486DX and SX, the Pentium (80586), the Pentium Pro (80686),
and Pentium II.
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Configuration Settings
Each time the system is turned on or reset, the BIOS program checks the
system’s configuration settings to determine what types of optional
devices have been included in the system. PCs feature a battery-powered
RAM area that holds some of the system’s advanced configuration
information. This configuration storage area became known as CMOS
RAM. Many system-board designs include a rechargeable, Ni-CAD
battery on their system boards to maintain the CMOS information when
the system was turned off. However, in some newer systems, there are no
rechargeable Ni-CAD batteries for the CMOS storage.
Instead, the CMOS storage area and Real Time Clock (RTC) functions
have been integrated with a 10-year, non-replaceable lithium cell in an
independent RTC IC.
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Connectors and Jumpers
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Expansion Slots
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The major expansion slot types are
8- bit PC-bus slots
16- bit AT-bus or Industry Standard
Architecture (ISA) bus slots
32- bit Extended ISA (EISA) and
Micro Channel Architecture
(MCA) bus slots
32- bit Video Electronics Standards
Association (VESA) and 32/64 bit
Peripheral Component Interconnect
(PCI) local bus
slots
POWER SUPPLIES
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The ATX ystem
board connector
is a 20-pin
keyed connector
Power Supplies – Cont.
In AT-compatible power supplies, two six-
wire bundles, typically marked P8 and P9,
deliver power to the system board
A good rule of thumb to remember when
attaching these two connectors to the system
board is that the black wires from each
bundle should be side by side, as illustrated
in the figure.
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A P1/P2 to P8/P9 connection
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In AT-compatible power supplies, two six-
wire bundles, typically marked P8 and P9,
deliver power to the system board
A good rule of thumb to remember when
attaching these two connectors to the
system board is that the black wires from
each bundle should be side by side, as
illustrated in the figure.
ADAPTER CARDS
Most of the devices communicate with the basic system through adapter
cards that plug in to the expansion slots of the system board. They
typically contain the interfacing and controller circuitry for the
peripheral. Typical adapter cards used with PCs include
Video adapter cards
Modems
Local Area Network cards
Sound cards
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Video Adapter Cards
Standard VGA monitors employ a 31.5KHz horizontal scanning rate,
whereas Super VGA monitors use frequencies between 35 and 48KHz
for their horizontal sync, depending rate of the adapter card. Standard
VGA monitors repaint the screen on the vertical refresh(vertical refresh)
at a frequency of 60 or 70Hz, whereas Super VGAvertical scanning
occurs at frequencies of 56, 60, and 72Hz.
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Other Adapter Cards
Some of the most popular I/O cards in modern Pentium
systems include
Modem cards—Used to carry out data communications
through telephone lines
Local Area Network cards—Used to connect the local
system to a group of other computers so that they can share
data and resources
Sound cards—Used to provide high-quality audio output to
the computer system
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Fig 1.11
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STORAGE DEVICES
Magnetic storage has remained popular because of three
factors:
It has a low cost-per-bit of storage.
It is intrinsically nonvolatile in nature.
It has successfully evolved upward in capacity.
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Hard Drives Tracks is placed closer together than with floppy disks. This, in turn, makes its
storage capacity very high. Typical hard disks can have between 315 and 2,048
tracks on each side of each platter.
The term cylinder is used to refer to the collection of all the tracks possessing the
same number on different sides of the disks (that is, track0/side0, track0/side1,
track0/side2, and so on).
Each track on the hard drive is divided into between 17 and 65 equal-size sectors,
depending on the diameter of the disk. Sectors generally contain 512 bytes. The high
speed at which the hard disk revolves also provides very rapid data transfer rates.
Most hard disk drives in modern PCs employ Integrated Drive Electronics (IDE)
and Small Computer System Interface (SCSI) interfaces to connect them to the
system.
Typical hard disks can have between 315 and 2,048 tracks on each side of each
platter. Each track on the hard drive is divided into between 17 and 65 equal-size
sectors, depending on the diameter of the disk. Sectors generally contain 512 bytes.
The high speed at which the hard disk revolves also provides very rapid data transfer
rates.
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CD-ROM(compact disc)
Data is written digitally on a light-sensitive material by a
powerful, highly focused laser beam.
Data is encoded by the length and spacing of the blisters
(pits), and the lands between them. The recorded data is read
from the disc by scanning it with a lower-power, continuous
laser beam.
The information on a compact disc is stored in one continuous
spiral track—unlike magnetic disks where the data is stored in
multiple, concentric tracks.
The CD storage format still divides the data into separate
sectors. However, the sectors of a CD-ROM disc are
physically the same size
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Encoding data on a CD-ROM.
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DVD(Digital Versatile Discs)
These discs have capacities that range between 4.7 GB and 17 GB of data.
Transfer rates associated with DVD drives range between 600Kbps and
1.3Mbps.
DVDs are available in DVD-ROM (write-once) and DVD-RAM
(rewritable) formats.
DVD drives also employ higher resolution lasers to decrease the track
pitch (distance between adjacent tracks).
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PERIPHERALS AND PORTS
Peripherals are devices and systems that are added to the
basic system to extend its capabilities. These devices and
systems can be divided into three general categories: input,
output, and memory systems.
Peripheral devices are attached to the system through I/O port
connections.
Ports offer standard hardware connection and logical interface
schemes that permit I/O device manufacturers to develop their
products to predefined standards.
PCs offer a wide variety of different port types to
accommodate as many diverse device types as possible.
The standard peripherals used with PCs are keyboards, CRT
monitors, and mice.
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Keyboards
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Video Displays
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The sweeping electron beam begins at the upper-left corner of
the screen, and moves across its face to the upper-right corner,
leaving a line across the screen. This is called a raster line.
Upon reaching the right side of the screen, the trace is
blanked out and the electron beam is repositioned to the left
side of the screen—one line below the first trace—in an
operation called the horizontal retrace.
At this point, the horizontal sweep begins producing the
second display line on the screen. The scanning continues
until the horizontal sweep reaches the bottom of the screen. At
that point, the electron beam is blanked again and returned to
the upper-left corner of the screen in a move referred to as the
vertical retrace, completing one field.
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As the beam moves across the screen, it leaves an illuminated
trace, which requires a given amount of time to dissipate. The
amount of time depends on the characteristics of the
fluorescent coating and is referred to as persistence. Video
information is introduced to the picture by varying the
voltage applied to the electron gun as it scans the screen.
The human eye perceives only the picture due to the blanking
of the retrace lines and the frequency at which the entire
process is performed. Typically, a horizontal sweep requires
about 63 microseconds to complete, whereas a complete field
requires approximately 1/60 of a second.
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Color Monitors
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Screen Resolution
The quality of the image produced on the screen is a
function of two factors: the speed at which the image is retraced on the screen
the number of pixels on the screen. The more pixels on a given screen
size, the higher the image quality.
This quantity is called resolution, and is often
expressed in an X-by-Y format.
Resolution can be expressed as a function of how
close pixels can be grouped together on the screen.
This form of resolution is expressed in terms of dot
pitch. A monitor with a .28 dot pitch has pixels that
are located .28mm apart.
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MODEMS
A modem consists of two major blocks: a
modulator and a demodulator. The modulator is
a transmitter that converts the parallel/digital
computer data into a serial/analog format for
transmission
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Modem Communications
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SOFTWARE
The term software refers to the logical
instructions and data that can be stored in
electronic form and used to control the
operation of the computer. Three general
classes of software can be discussed:
system software
applications software
games and learning software
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System Software
The system software category consists of
special programs used by the system itself to
control the computer’s operation.
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BASIC INPUT/OUTPUT SYSTEMS
During the execution of the BIOS firmware routines, three major sets of operations
are performed.
1. First, the BIOS performs a series of diagnostic tests (called POST or Power On
Self Tests) on the system to verify that it is operating correctly. The main functions
provided by the POST .
2. Next, the BIOS places starting values in the system’s various programmable
devices. These intelligent devices regulate the operation of different portions of the
computer’s hardware. This process is called initialization. The end of the
POST/initialization process is typically marked by an audible signal such as a
single beep.
3. Finally, the BIOS performs the bootstrap loader sequence where it searches the
system for a special program that it can use to load other programs into RAM. This
program is called the Master Boot Record (MBR). The boot record contains
information that enables the system to load a much more powerful control
program, called the disk operating system (DOS), into RAM memory. This
operation is referred to as bootup
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The steps of a bootup: Phase One—POST.
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The steps of a bootup: Phase Two—Initialization
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The steps of a bootup: Phase Three—Bootup
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OPERATING SYSTEMS
Operating systems are programs designed to control
the operation of a computer system.
A disk operating system, or DOS, is a collection of
programs used to control overall computer operation
in a disk-based system. These programs work in the
background to enable the user of the computer to
interact with it
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DOS can be divided into four distinct sections:
Boot files—Take over control of the system from the ROM
BIOS during startup.
Kernel files—The basic set of files that make up the
basic core of the operating system.
File management files—Enable the system to manage
information within itself.
Utility files—Permit the user to manage system
resources, troubleshoot the system, and configure the
system.
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System Resources
the chapter deals with common methods of controlling
the movement of data through the system.
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