computer peripherals - bu

Computer peripherals

11/22/2014

Computer peripherals

Dr. Mazen Selim 1

Grading

Homework 20%

Midterm Exam 20%

Final Exam 60%

11/22/2014 Computer peripherals Dr. Mazen Selim 2

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Microsoft

A+ certification

IT professional


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.


The PC System


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


Inside a desktop unit


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.


System Boards


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.


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.


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.


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.


Connectors and Jumpers


Expansion Slots


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


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.


A P1/P2 to P8/P9 connection


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


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.


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


Fig 1.11


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.


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.


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


Encoding data on a CD-ROM.


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).


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.


Keyboards


Video Displays


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.


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.


Color Monitors


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.


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


Modem Communications


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


System Software

The system software category consists of

special programs used by the system itself to

control the computer’s operation.


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


The steps of a bootup: Phase One—POST.


The steps of a bootup: Phase Two—Initialization


The steps of a bootup: Phase Three—Bootup


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


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.


System Resources

the chapter deals with common methods of controlling

the movement of data through the system.


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