Transcript Introduction to Computer Organization and Architecture

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Describe the general organization and
architecture of computers.
Identify computers’ major components and
study their functions.
Identify the various I/O peripherals and
storage devices.
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A computer is an electronic
device that stores, accepts
data, retrieves data,
processes data and gives
output according to a set of
instructions.
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Hardware
Physical components
Software
Computer instructions
User
Human operator
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Input
CPU
Device
Output
Device
Backing
Store
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 This
is the equipment that
make up a computer system
(physical components).
 Many of these parts are
contained within the
computer’s case.
 Other parts are connected to
the computer (peripheral
devices). These allow data to
be entered (input) and
retrieved (output) and stored
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Computer components
 Input
devices (mouse and
keyboard) let the user enter data
 Processing devices (processor)
 Output devices (monitor,
speakers and printer) display data
 Storage devices (memory sticks
and disks) hold data
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The part of the computer performs the bulk
of data processing operations is called the
central processing unit
“Brain” as well as “heart” of computer
system
The chip or chips at the heart of a computer
that enable it to process data.
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The CPU is made up of four major parts:
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Register set
ALU
Control units
Main memory
 Memory: An area within a computer system that
holds data waiting to be processed.
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Control unit
◦ Control unit: supervises the transfer of information
among the registers and instructs the ALU as to which
operation to perform by generating control signals.
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Arithmetic logic unit (ALU)
◦ Performs computation and comparison operations
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Set of registers
◦ Storage locations that hold inputs and outputs for the
ALU
◦ Stores intermediate data during the execution of
instructions;
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Primary functions
◦ Hold data for currently executing program that is
needed quickly or frequently (general-purpose
registers)
◦ Store information about currently executing
program and about status of CPU (special-purpose
registers)
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Input is any data entered into the computer’s
memory.
input devices : the devices that allow data and
instructions to enter a computer (such as a
keyboard, mouse, scanner)
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Types of input include:
◦ Data – Unorganized information (words, numbers,
images, or sounds) that the computer converts to
meaningful information
◦ Software – Programs transferred from storage
devices to the computer’s memory
◦ Commands – Instructions that tell the computer
what to do
◦ Responses – Prompts requiring user feedback
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Input device is any device that is used to
transfer data into a computer so that it may
be processed or stored permanently.
Each type of input device has an INTERFACE
i.e a means of communication between the
human user and the electronic computer
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Data may be keyed in from source documents
by keyboard operators
 Computer Keyboard
 Numeric keypad
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The source documents may be read directly
by a document reader. Document readers
capture information in the form of pictures or
text already printed on paper.
 Image Scanners
 Optical Character reader (OCR)
 Optical Mark reader (OMR)
 Magnetic ink character reader (MICR)
 Bar code readers
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Data may be captured directly without the
need for any source document
 Magnetic strip on a plastic card,
 Smart card
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Graphic input devices may be used to
translate drawings or photographs into digital
form that can be processed by a computer
 Mouse
 Track ball
 Touch screen
 Digitizing tablet
 Light pen
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A microphone can be attached to a sound
card to provide audio input and also to issue
commands and crate files
Speech recognition is a type of input in which
the computer recognizes words spoken into a
microphone.
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Output devices are peripheral devices that
enable us to view or hear the computer’s
processed data. E.g. a display screen or
printer)
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Output: The product of the transformation
of inputs by a process.
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Types of output
◦ Visual output – Text, graphics, and video
◦ Audio output – Sounds, music, and synthesized
speech
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A monitor is a peripheral device which
displays computer output on a screen.
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Screen output is referred to as soft copy.
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Types of monitors:
◦ Cathode-ray tube (CRT)
◦ Liquid Crystal Display (LCD or flat-panel)
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A printer is a peripheral device that
produces a physical copy or hard copy of
the computer’s output.
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Laser
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Laser printer works like a copier
Quality determined by dots per inch (dpi) produced
Color printers available
Expensive initial costs but cheaper to operate per
page
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Inkjet
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Inkjet printer, also called a bubble-jet, makes
characters by inserting dots of ink onto paper
Letter-quality printouts
Cost of printer is inexpensive but ink is costly
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A plotter is a printer that uses a pen that
moves over a large revolving sheet of paper.
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It is used in engineering, drafting, map
making, and seismology.
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Audio output is the ability of the computer to
output sound.
Two components are needed:
◦ Sound card – Plays contents of digitized recordings
◦ Speakers – Attach to sound card
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Storage device:
◦ The place where a computer puts data.
◦ The area within a computer system where data can
be left on a longer term basis while it is not needed
for processing.
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Storage devices:
◦Retain data when the computer is turned off
◦Are cheaper than memory
◦Play an important role during startup
◦Are needed for output
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Magnetic Storage
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Optical Storage –
CD/DVD drive
Magnetic – Storage devices use disks or tapes
that are coated with magnetically sensitive
material
Optical – Storage devices that use laser beams to
read patterns etched into plastic disks
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CD-ROM stands for Compact
Disc-Read Only Memory.
CD-ROM drives can not write
data to discs.
They are capable of storing
650 MB of data.
They are used for storing
operating systems, large
application programs, and
multimedia programs.
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CD-R
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Discs can be read and written to
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Discs can only be written to “once”
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CD-R drives are capable of reading and
writing data
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CD-RW
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Discs can be read and written to
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Discs are erasable
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Discs can be written to many times
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CD-RW drives are capable of reading,
writing, and erasing data
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DVD stands for Digital Video Disc.
DVD technology is similar to CDROM technology.
DVDs are capable of storing up to
17GB of data.
The data transfer rate of DVD
drives is comparable to that of hard
disk drives.
DVD-R and DVD-RW drives have
the ability to read/write data.
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Solid state storage devices use nonvolatile
memory chips to retain data.
They do not have moving parts.
They are small, lightweight, reliable, and
portable.
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Smart
Card
Flash
Memory
PC
Card
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Memory
Stick
Compact
Flash
Memory
Micro
Drive
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