What is a system?
A system is defined a set of interrelated components, with a
clearly defined boundary, working together to achieve a
common set of objectives by accepting input and producing
It has three basic functions:
INPUT : involves capturing and assembling elements that enter
the system to be processed.
Ex-raw materials, energy and data.
PROCESSING: involves transformation processes that convert
input into output.
Ex-manufacturing processes, mathematical calculation.
OUTPUT: involves transferring elements that have been
produced by transformation process to there ultimate
Ex-finished products, human services.
The system concept becomes more useful by including to
elements, feedback and control. A system with feedback and
control functions is called a cybernetic system.
FEEDBACK: is data about the performance about the system.
Ex-data about sale performance are feedback to sales manager.
CONTROL: involves monitoring and evaluating feedback to
determine whether a system is moving towards the
achievements of its goal.
It makes necessary adjustments to a system input and
processing components. Ex-a sales manager exercise control
when reassigning sales person to new sales territories
A model that expresses a fundamental conceptual framework
for the major components and activities is called IT system. it
highlighted the relationships among the components and
activities of information system. It also provides a framework
that emphasis concepts that can be applied to all types of
People are the essential ingredient for the successful operation
of all information system. It includes end users and IS
END USERS are people who use an information system or the
information it produces. They can be customers , sales person
are found at all levels.
IS SPECIALIST are people who develop and operate
information system. It includes system analysts, software
It includes all physical devices and material used in
information processing. It includes not only machines, such as
computers but also all data media, i.e. tangible objects on
which data is recorded. Ex-
COMPUTER SYSTEM : consist of central processing units
containing micro processors and a variety of interconnected
devices such as printers , scanners etc.
COMPUTER PERIPHERALS: are devices such as
keyboard, electronic mouse for the input of data and
commands , a video screen or printers for the output of the
It includes all sets of information processing instructions. This
generic concept includes not only the sets of operating
instructions called programs which direct and control computer
hardware but also the set of information processing instruction
called procedure that people need.
This concept has been broadened by managers and information
system professionals. They realize the data constitute valuable
organizational resources. It resulted in variety of changes in
modern organization. Under this data can take many forms
including traditional numeric data composed of numbers etc.
The data resources of information system are typically
organized, stored, accessed by a variety of data resource
management technologies into:
Data base that hold processed and organize data.
Knowledge bases that hold knowledge in a variety of forms
such as facts.
It emphasizes that communications technologies and networks
are fundamental resource components of all information
system. It includes:
Communication Media- includes twisted pair
wire, microwave, cellular wireless technologies.
Network Infrastructure- emphasizes that many
hardware, software and data technologies are needed to
support the operations and use of communication network.
Ex-communication processors such as modems.
TYPES OF COMPUTER SYSTEMS
There are three categories of computer systems:
Microcomputers are the most important category of computer
systems for both business people and consumers.
Microcomputers have become powerful networked
professional workstations for business professionals.
Examples: personal computers, networked
computers, technical workstations, information appliances.
Midrange systems are primarily are high-end network servers
that can handle the large scale processing of many business
Midrange systems first became popular as minicomputers for
scientific research, engineering analysis, instrumentation
systems, and industrial process monitoring and control.
Midrange systems are used as front-end servers to assist
mainframe computers in telecommunications processing and
Examples: network servers, minicomputers, web servers and
Mainframe systems are large, fast and powerful computer
They have large primary storage capacity.
They handle the information processing needs of major
corporations and government agencies with high transaction
processing volumes or complex computational problems.
Examples: enterprise systems, super servers, and super
Peripherals is a generic name given to all input , output and
secondary storage devices that are a part of a computer
Peripherals depend on direct connections or
telecommunications link to the central processing unit of a
computer system .
Input technologies now provide a more natural user interface
for computer systems you can enter the data directly & easily
into computer through pointing devices like electronic mice
and touch pads and with technologies like optical scanning
, handwriting recognition , voice recognition .
Pointing devices are used for issuing commands , making
They include devices such as electronic mouse, trackball and
touch pads .
Electronic mouse: It is most popular device used to move the
cursor on the screen to issue commands and make selections .
Touch pads: It is a small rectangular touch sensitive surface
usually placed below the keyboard the cursor moves in
direction your fingers move on pad.
Pen based computing
Instead of using keyboard or clipboard you can use a pen to
make selections, send e-mails, draw or write.
Various pen devices are available such as digitizer pen and
Speech recognition systems
Speech recognition systems analyze and classify your speech
and sound patterns . Software compares your speech patterns
to a database of sound patterns and passes the recognized
words to your application software
Devices in workplace allow operators to perform data entry
without their hands on keys .
Optical scanning devices read text or graphics and convert
them into digital input for your computer .
OCR (optical character recognition) is also a type of optical
scanning technology . OCR scanners can read characters and
codes on product labels, airline tickets etc
Computer users depend on memory circuits and secondary
storage devices of computer systems to meet storage
Progress in very-large-scale integration (VLSI), which packs
millions of memory circuit elements on tiny semi-conductor
memory chips, is responsible for continuing increases in main
memory capacity of computers.
High speed storage media cost more per byte and provide
Large capacity storage media cost less per byte but are slower.
Primary storage circuits use RAM chips, which loose their
contents when electrical power is interrupted while secondary
storage devices provide a more permanent type of storage
Computer storage fundamentals
Data are processed and stored in a computer system through
the presence or absence of electronic or magnetic signals in
the computer circuitry or in the media it uses.
This character is called two-state or binary representation of
data because the computer and media can exhibit only two
possible states or conditions, similar to a common light
switch: “on” or “off”.
The smallest element of data is called bit, which can have a
value of either zero or one.
The capacity of memory chips is usually expressed in terms of
A byte is a basic grouping of bits that the computer operates as
a single unit.
Storage capacities can be measured in
kilobytes, megabytes, gigabytes or terabytes.
There are four types of storage trade-offs-
o Semiconductor memory
o Magnetic disks
o Optical disks
o Magnetic tape
Direct and sequential access
Primary storage media such as semiconductor memory chips
are called direct access memory or random access memory.
Secondary storage media such as magnetic tape cartridges are
known as sequential access devices.
The concepts described by Direct and sequential access are as
An element of data or instructions can be directly stored and
retrieved by selecting and using any of the locations on
Each storage position has a unique address and can be
individually accessed in approximately the same length of
time without having to search through other storage positions.
The primary storage of a computer consists of microelectronic
It provides with the working storage a computer needs to
Attractions of semiconductor memory are-
o Small size
o Great speed
o Shock resistance
o Temperature resistance
Two basic types of semiconductor memory are-
Random Access Memory(RAM): These memory chips are
most widely used primary storage medium. Each memory
position can be both sensed(read) and changed(written), so it
is called read/write memory. This is a volatile memory.
Read Only Memory(ROM): Non-volatile memory chips are
used for permanent storage; ROM can be read but not erased
Magnetic disks are the most common form of secondary
storage for a computer system.
They provide fast access and high storage capacities at a
Data are recorded on tracks in the form of tiny magnetized
spots to form the binary digits of common computer codes.
Thousands of bytes can be recorded on each track, and there
are several hundred data tracks on each disk surface, thus
providing us with billions of storage positions for software
Redundant Arrays of Independent Disks(RAID) combine from
6 to more than 100 small hard disk drives and their control
microprocessors into a single unit.
RAID units provide large capacities with high access speeds
because data are accessed in parallel over multiple paths from
They provide a fault-tolerant capacity, in which their
redundant design offers multiple copies of data on several
If one disk fails, data can be recovered from backup copies
automatically stored on other disks.
Tape storage is moving beyond backup. Although disk
subsystems provide the fastest response time for mission-
critical; data, the sheer amount of data that users need to
access these days as part of huge enterprise applications, such
as data warehouse, requires affordable (magnetic tape)
On growing business application of magnetic tape involves
the use of high-speed 36-track magnetic tape cartridges in
robotic automated drive assemblies that can directly access
hundreds of cartridges.
Other major applications for magnetic tape include long-term
archival storage and backup storage for PCs and other
Optical disk technology has become a necessity. Most
software companies now distribute their elephantine programs
It is a fast-growing type of storage media.
Examples :- CD-ROM, CD-RW, DVD, DVD-ROM etc.
One of the use of optical disks in mainframe and midrange
systems is in image processing, where long-term archival
storage of historical files of document images must be
Interactive multimedia applications in
business, education, and entertainment area another major use
of optical disks.
Financial institutions, among others, are using optical
scanners to capture digitized document images and store them
on optical disks as an alternative to microfilm media.
One of the newest and most rapidly growing storage
technologies is radio frequency identification [RFID] a system
for tagging and identifying mobile objects such as store
merchandise, postal packages, and sometimes even living
Using special device called an RIFD reader, RFID allows
objects to be labeled and tracked as they move from place to
RFID technology works using small pieces of hardware
called RFID chips. These chips feature an antenna to transmit
and receive radio signals. These are of 2 types passive and
Passive chips do not have a power source and active chips
are self powered and do not need to be close to the reader to
transmit their signal.
The RIFD systems were created as an alternative to common
RFID Privacy Issues
The use of RFID technology has caused considerable
controversy and even product boycotts by consumer privacy
advocates who refer to RFID tags as spy chips.
The 2 main privacy concerns are:
1. Since the owner of an item will not necessarily be aware of
the presence of an RFID tag, and the tag can be read at a distance
without the knowledge of the individual, it becomes possible to
gather sensitive data about an individual without consent.
2. If a customer pays by a credit card, then it would be
possible to deduce the identity of the purchaser indirectly by
reading the globally unique ID of that item.
Enhancing Security using RFID
RFID presents the potential for enormous efficiencies and
It also presents significant challenges to privacy and security.
example-Chennai air port