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2 Information
Processing
2.1 Basic Knowledge of
Computer Platforms
*
3 Processing Stages

Input
– Enter data into the computer

Processing
– The computer works on the data

Output
– The processed data or results are given out by
the computer
INPUT
data
info.
PROCESSING
OUTPUT
5 Components of a
Typical PC
Input devices
 Output devices
 Processing unit
 Primary storage units / Main memory
 Secondary storage units / Backing
storage devices

*
Input devices


*
Input devices are used for entering data (e.g.
characters, numbers, sound, video, graphics
and etc.) into the computer
E.g., mouse, keyboard, digitizer,
microphone, bar-code reader, smart card
(e.g. Octopus), scanner, Optical character
recognition software, speech recognizer,
Chinese handwriting recognizer, touching
screen and etc.
Output devices
Output devices are used for displaying
processed data or information (e.g.
graphics & movies on screen, printouts,
sound and etc.) to the users
 E.g., monitor (visual display unit),
printer, speakers, plotter and etc.

*
Processing unit



*
At the heart of every computer is the central
processing unit (CPU), or processor, which
executes program instructions and performs
the computer's processing actions.
The CPU is a collection of electronic circuits
made up of thousands of transistors placed
onto an integrated circuit (also called a chip
or microchip).
The two components of the CPU are the
control unit (CU) and the arithmetic/logic
unit (ALU)
Common CPU brands
Primary storage units
it holds data only temporarily as the
computer executes instructions.
 2 kinds of primary storage device:

– RAM (Random Access Memory)
– ROM (Read Only Memory)
*
RAM
ROM

RAM
– memory that permits data or information to be
written into or read from any memory address at
any time.
– RAM stores data and information only as long as
the computer is turned on (volatile).

ROM
– offers random access to data, but it can hold
data and information after the electric current to
the computer has been turned off (non-volatile).
– data can be read from memory but cannot be
written into it
*
Secondary storage unit
augments primary memory
 is used to store data over the long
term or for future use.
 E.g., hard disks, floppy diskettes,
magnetic tapes, CD-ROM (read-only),
CD-R (recordable), CD-RW
(rewrittable), DVD, magneto-optical
(MO) disks, zip disks, jaz disks and etc.

*
Why need secondary
storage?



contents of primary memory remain
there only temporarily.
data vanishes from primary memory
as soon as the computer is turned off.
Primary memory is not large enough
to contain the large volume of data
and information associated with
business application.
The relationship
between 5 components
Input devices
Processing unit
Primary storage
Output devices
Secondary storage
*
4 step processing
The processing sequence is a four step
processing called the machine cycle. These
four steps, all of which are directed by the
control unit, are as follows:
 fetch, or obtain the next instruction form
memory;
 decode, or translate the instruction into
individual commands that the computer can
process;


execute, or perform the actions
called for in the instructions; and
store, or write the results of
processing to memory. To execute
the machine cycle, the control unit
depends on registers, temporary
storage areas in the processor.
Communication device

Modem
– A modem modulates outgoing digital
signals from a computer or other digital
device to analog signals for a
conventional
copper
twisted-pair
telephone line and demodulates the
incoming analog signal and converts it to
a digital signal for the digital device.
*

Analog
and
conversion
digital
signal
– Digital-to-analog conversion is a process
in which signals having a few (usually two)
defined levels or states (digital) are
converted
into signals having a
theoretically infinite number of states
(analog).
*
Modulation
A modem modulates outgoing digital
signals from a computer or other digital
device to analog signals for a
conventional
copper
twisted-pair
telephone line.
 Demodulation
A modem demodulates the incoming
analog signal and converts it to a
digital signal for the digital device.

*
Major Items Affect the
Performance of Computer
Operations
CPU
 RAM
 Cache
 Video memory
 Display adapter

*
CPU

Clock speed is one measure of
computer "power," but it is not always
directly proportional to the
performance level.
– http://whatis.techtarget.com/definition/0,,s
id9_gci211799,00.html
From whatis.com
Bus
A bus is the path over which data are
moved.
 The width of the bus determines the
amount of data that can be moved at
one time.

Word
Word size is measured in bits. A word
is the number of bits a computer can
process simultaneously.
 The larger the word size, the faster a
computer can process data.

Memory

The computer's workspace (physically,
a collection of RAM chips). It is an
important resource, since it determines
the size and number of programs that
can be run at the same time, as well
as the amount of data that can be
processed instantly.
From whatis.com
From techweb.com
Cache
L1 and L2 are levels of cache memory
in a computer.
 If the computer processor can find the
data it needs for its next operation in
cache memory, it will save time
compared to having to get it from RAM.

From whatis.com
L1 is "level-1" cache memory, usually
built onto the microprocessor chip itself.
For example, the Intel MMX
microprocessor comes with 32
thousand bytes of L1.
 L2 (that is, level-2) cache memory is
built into the CPU chip or on a
separate chip that can be accessed
more quickly than the larger "main"
memory. A popular L2 cache memory
size is 1 MB.

From whatis.com
From techweb.com
Video RAM

Also called "VRAM," it is a type of
memory used in a display adapter. It is
designed with dual ports so that it can
simultaneously refresh the screen
while text and images are drawn in
memory. It is faster than the common
dynamic RAM (DRAM) used as main
memory in the computer.
From techweb.com
Display adapter


An expansion board that plugs into a
desktop computer that converts the images
created in the computer (digital) to the
electronic signals (analog) required by the
monitor.
The display adapter converts the characters
or graphic patterns (bitmaps) within the
computer's memory into signals used to
refresh the display screen.
From techweb.com

Display adapters also contain their
own memory, which is used to build
the images before they are displayed
From techweb.com
From techweb.com
6 Ways of Increasing
Processing and Computer
Speed

Cache memory
–

a form of high-speed memory that acts as a
temporary
holding/processing
cell
and
eliminates the need to move data to and from
the main memory repeatedly.
Co-processors
–
special chips designed to handle tasks that are
performed often.
By taking over this
processing work from the main processor, they
free the CPU to focus on general processing
needs.

Accelerator boards
– are add-in circuit boards that increase a
computer's processing speed.

Packing more transistors on a chip
– creating greater chip density, resulting
in greater computing speed.

Reduced
(RISC)
–

instruction
set
computing
processes data more simply than complex
instruction set computing. With RISC, data for
the execution of an instruction are taken only
from register.
This both simplifies and
accelerates instruction processing.
With parallel processing
–
computing handle different parts of a problem
by executing instructions simultaneously. In
the end, the results of each parallel process
are combined to produce a result.
Some Common Storage
Devices
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*
CD-ROM
CD-R
CD-RW
DVD
Zip
Jaz
Floppy diskettes
Hard disks
From techweb.com
CD-ROM



(Compact Disc Read Only Memory) A
compact disc format used to hold text,
graphics and hi-fi stereo sound.
It's like an audio CD with spiral, grooved
tracks, but uses a different format for
recording data.
The audio CD player cannot play CD-ROMs,
but CD-ROM players can play audio discs.
From techweb.com
CD-ROMs hold 650MB of data, which
is equivalent to about 250,000 pages
of text or 20,000 medium-resolution
images.
 The first CD-ROM drives transferred
data at 150KB per second (1X).
Speeds doubled to 300KBps (2X) and
continued upward to more than 40
times (40X) the original. Access times
range from 80 to 120ms.

From techweb.com



The 120mm CD-ROM is the
de facto standard for
software distribution and
for publishing large
databases.
The smaller mini CD-ROM is
only 80mm in diameter and
holds 180MB (compared to
the full-size 650MB). It fits
into the deeper well in the
center of the tray in most
CD-ROM drives.
CD-ROMs have a silver cast
just like audio CDs.
From techweb.com
From techweb.com

There is only one laser in a drive. Two are
used here to illustrate the difference in
reflection
From techweb.com
How a CD-ROM is
made ?
From techweb.com
From techweb.com
From techweb.com
CD-R



(CD-Recordable) A recordable CD-ROM
technology using a disc that can be written
only once.
The drive that writes the CD-R disc is often
called a "one-off machine" and can also be
used as a regular CD-ROM reader.
CD-Rs create the equivalent of pits in the
disc by altering the reflectivity of a dye layer.
Different dyes can be used, including
cyanine (green), pthalo-cyanine (yellow-gold)
and metal-azo (blue).
From techweb.com

Blank CD-R discs can be recorded
once and read on any CD-ROM
reader. CD-Rs have a gold, blue or
green cast.
From techweb.com
CD-R discs are used for beta versions
and original masters of CD-ROM
material as well as a means to
distribute large amounts of data to a
small number of recipients.
 CD-Rs are also used for archiving
data. A major advantage over other
media is that they can be read in
most CD-ROM drives.

From techweb.com
"Burning" your own CD-Rs is very
efficient for small distributions or
when it is vital to create copies
immediately.
 However, when several hundred or
more discs must be created, the CDROM manufacturing process is
generally more efficient.
 CD-ROMs are made on a pressing
machine from a master plate that was
derived from a CD-R recording.

From techweb.com
From techweb.com
From techweb.com

CD-R drives such as this internal drive from
Sony look just like CD-ROM drives. Only the
discs themselves look different. The
underside of CD-R media typically has a
greenish-gold or
silver-blue cast,
whereas CDROMs have a
silver cast.
(Image courtesy
of Sony
Electronics Inc.)
From techweb.com
From techweb.com
(Image courtesy of Cedar
Technologies.)
From techweb.com
CD-RW




(CD-ReWritable) A rewritable CD-ROM
technology.
CD-RW drives can also be used to write
CD-R discs, and they can read CD-ROMs.
But, CD-RW disks have a lower reflectivity
than CD-ROMs and CD-Rs, and newer
MultiRead CD-ROM drives are required to
read them.
Initially known as CD-E (for CD-Erasable), a
CD-RW disk can be rewritten a thousand
times.
From techweb.com




CD-RW disks can be used to master CDROMs, and the same software used for CDR creation supports this application.
However, unlike CD-Rs, in which the entire
disc or an entire track is recorded at once,
CD-RWs support UDF (Universal Disk
Format), which is similar to the file system
on a hard disk.
Using variable packet writing, small
numbers of files can be appended, and
using fixed packet writing, files can be
added and deleted.
The fixed packet approach requires
preformatting like a floppy disk, but takes
considerably longer.
From techweb.com





CD-RWs use phase change technology to
alter the reflectivity of the disk's surface.
Phase change is a pure optical technology
and does not rely on any magnetic influence
as does magneto-optic and its progeny.
A short, high-intensity laser pulse turns a bit
in the recording layer from its natural
crystalline state (reflective) to an amorphous
one (dull), which does not reflect light as
well.
A medium-intensity pulse restores the
crystalline structure.
A low-intensity pulse reads the bit.
From techweb.com
From techweb.com
DVD

DVD originally stood for Digital Video
Disc. Since the technology began to
seem as important for the computer
world as it did for the video world, the
"video" was dropped, and it became
simply D-V-D. Later, it was dubbed
Digital Versatile Disc.
From techweb.com



DVD is an optical disc technology that is
expected to rapidly replace the CD-ROM
disc (as well as the audio compact disc)
over the next few years.
A DVD holds 4.7 gigabytes of information on
one of its two sides, or enough for a 133minute movie.
With two layers on each of its two sides, it
will hold up to 17 gigabytes of video, audio,
or other information. (Compare this to the
current CD-ROM disc of the same physical
size, holding 600 megabytes. The DVD can
hold more than 28 times as much
information!)
From whatis.com
Types of DVDs





DVD-Video is the usual name for the DVD
format designed for full-length movies and is
a box that will work with your television set.
DVD-ROM is the name of the player that will
(sooner or later) replace your computer's
CD-ROM. It will play regular CD-ROM discs
as well as DVD-ROM discs.
DVD-R is a write-once version used for
creating masters
DVD-RAM is the writeable version.
DVD-Audio is a player designed to replace
your compact disc player.
From whatis.com and techweb.com
DVD-Video format



DVD-Video uses MPEG-2 compression
providing approximately 133 minutes of
Laser Disc-quality video per side.
This is not a fixed length, because the
compression rate is based upon the amount
of motion taking place.
DVD-Video supports Dolby Digital surround
sound, which provides five discrete
channels of CD-quality audio plus a
subwoofer (5.1 channel).
DVD-Audio format

DVD-Audio is a second-generation digital
music format that provides higher sampling
rates than audio CDs. Many have welcomed
the new format, believing that the original
audio CD was unable to capture the total
sound spectrum.
From techweb.com
From techweb.com

At minimum, the capacity of a DVD is 750%
that of a CD-ROM because its tracks, pits
and lands are more than twice as dense,
and it uses more efficient recording
algorithms. (Image courtesy of C-Cube
Microsystems.)
From techweb.com
From techweb.com
Zip




A 3.5" removable disk drive from Iomega.
It uses design concepts from Iomega's
Bernoulli technology as well as hard disks to
provide 100MB removable cartridges.
The drive is bundled with software that can
catalog the disks and lock the files for
security.
In late 1998, a 250MB version of the Zip
drive was introduced which also reads and
writes the 100MB cartridges.
From techweb.com
From techweb.com
Jaz disks
A high-capacity removable hard disk
system from Iomega.
 The Jaz has been very popular.
 In 1997, 2GB drives were introduced,
which support 1GB and 2GB
cartridges
 Usually used for backup data

From techweb.com
From techweb.com
Floppy diskettes



A reusable magnetic storage medium
introduced by IBM in 1971.
The floppy was the primary method for
distributing personal computer software until
the mid-1990s when CD-ROMs became the
preferred medium.
The floppy disk used today is the rigid 3.5"
microfloppy that holds 1.44MB. The reason
it's called a floppy is that the first varieties
were housed in bendable jackets. Floppies
are terribly undersized for today's use, and
their future is uncertain.
From techweb.com

Floppies spin at 300 rpm, which is from 10
to 30 times slower than a hard disk. They
are also at rest until a data transfer is
requested.
From techweb.com
From techweb.com
Hard disk



The primary computer storage medium,
which is made of one or more aluminum or
glass platters, coated with a ferromagnetic
material.
Most hard disks are fixed disks, which are
permanently sealed in the drive.
Removable cartridge disks such as
Iomega's Jaz disks enable the disk to be
removed from the computer and used as
backup or transferred to another machine
with the same drive.
From techweb.com




Most desktop hard disks are either IDE (also
known as EIDE or ATAPI) or SCSI.
The advantage of IDE is their lower cost.
The advantage of SCSI is that up to seven
or more devices can be attached to the
same controller board.
SCSI drives are typically used in high-end
servers, because SCSI is available as a
fault tolerant disk subsystem (RAID
systems), while IDE drives are found in
most desktop and laptop machines.
Increasingly, IDE drives are available in
RAID configurations
From techweb.com



Hard disks provide fast retrieval because
they rotate constantly at high speed, from
5,000 to 15,000 rpm. In laptops, they can be
turned off when idle to preserve battery life.
Today's hard disks start around 20
gigabytes and generally use 3.5" platters for
desktop computers and 2.5" platters for
notebooks.
Hard disks are usually low-level formatted
from the factory, which records the original
sector identification on them.
From techweb.com
From techweb.com
(Image courtesy of Seagate Technology,
Inc.)
From techweb.com
IBM's Microdrive Introduced in late 1998
with a platter the size of a quarter, IBM's
340MB Microdrive weighs less than an AA
battery.
From techweb.com
Size of Data






*
bits (binary digit)
byte = 8 bits
Kbyte (kilo byte KB) = 1024 or 210 bytes
Mbyte (mega byte MB) = 1,048,576 or 220
bytes
Gbyte (giga byte GB) = 1,073,741,842 or
230 bytes
Tbyte (tera byte TB) = 1,099,511,627,776 or
240 bytes
bit
(BInary digiT) The smallest element /
unit of computer storage. It is a single
digit in a binary number (0 or 1).
 The bit is physically a transistor or
capacitor in a memory cell, a magnetic
domain on disk or tape, a reflective
spot on optical media or a high or low
voltage pulsing through a circuit.

*
From techweb.com
Bits are widely used as a
measurement for transmission. Ten
megabits per second means that ten
million pulses are transmitted per
second. A 16-bit bus means that there
are 16 wires transmitting the bit at the
same time.
 Measurements for storage devices,
such as disks, files and databases, are
given in bytes rather than bits.

*
From techweb.com
From techweb.com
From techweb.com
Transmission – making
it faster
The bit is transmitted as a pulse of
high or low voltage.
 Speed is increased by making the
transistors open and close faster,
which is a combination of making the
microscopic elements within the
transistor smaller and more durable.

*
From techweb.com
Byte
Groups of bits make up storage units
in the computer, called "characters,"
"bytes," or "words," which are
manipulated as a group.
 The most common is the byte, made
up of 8 bits and equivalent to one
alphanumeric character.

*
From techweb.com
From techweb.com
From techweb.com
Storage - making it
smaller
Making the spot or cell smaller
increases the storage capacity.
 Holographic storage

*
From techweb.com
Types of Desktop
Computers & Workstation
File server
 Terminal
 Workstation

*
File server

*
The computer that a server program
runs in is also frequently referred to as
a server
From IT Teaching Kit
File server
A high-speed computer in a network
that stores the programs and data files
shared by users.
 It acts like a remote disk drive.

From techweb.com
Terminal



*
In data communications, a terminal is any
device that terminates one end (sender or
receiver) of a communicated signal.
In practice, it is usually applied only to the
extended end points in a network, not
central or intermediate devices.
In this usage, if you can send signals to it,
it's a terminal.
From IT Teaching Kit
Terminal



a terminal is an end-use device (usually with
display monitor and keyboard) with little or
no software of its own that relies on a
mainframe or another computer (such as a
PC server) for processing.
E.g. ATM machines
The term is sometimes used to mean any
personal computer or user workstation that
is hooked up to a network.
From whatis.com
File/database
server
Terminal
Application
server
Workstation
A workstation is a computer intended
for individual use but faster and more
capable than a personal computer.
 It's
intended
for
business
or
professional use (rather than home or
recreational use).

*
From IT Teaching Kit
Workstation


any individual personal computer location
hooked up to a mainframe computer/server
They're simply personal computers attached
to a local area network (LAN) that in turn
shares the resources of one or more large
computers. Since they are PCs, they can
also be used independently of the
mainframe assuming they have their own
applications installed and their own hard
disk storage.
From whatis.com
Peripheral Devices




A peripheral device is any computer device
that is not part of the essential computer
(the processor, memory, and data paths) but
is situated relatively close by.
A near synonym is input/output (I/O) device.
Some peripherals are mounted in the same
case with the main part of the computer as
are the hard disk drive, CD-ROM drive, and
NIC.
Other peripherals are outside the computer
case, such as the printer and image scanner,
attached by a wired or wireless connection.
5 common input
devices

Keyboards
–

Scanners
–
*
is the primary text input device. It contains
certain standard function keys, such as the key,
tab and cursor movement keys, shift and
control keys and any other manufacturercustomized keys.
transform written or printed information (optical
character
recognition
scanners)
or
photographic images, drawings, or entire
documents (image scanners) into a digital form
that is entered directly into the computer.

Mouse
– is a small device that a computer user pushes
across a desk surface in order to point to a place
on a display screen and to select one or more
actions to take from that position.

Digital cameras
– capture photographic images on light-sensitive
computer memory chips.

Voice input devices
– are attached to the computer to capture spoken
words and other sounds in digital form.
*
5 common output
devices

Video displays or monitors
– a monitor is a computer display and
related parts packaged in a physical unit
that is separate from other parts of the
computer.

Printers
– which produce paper output (hard copy)
*

Plotters
– draw image information, such as charts
and graphs, line drawings, and building
blueprints; and

Film recorders
– transform the electronic image on the
computer screen into a film image. The
uses of these devices vary greatly from
business to business, but all businesses
use output devices in their computer
systems
*