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CONCEPTS AND COMPONENTS OF
INFORMATION SYSTEM
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 outputs.
It has three basic functions: INPUT PROCESSING OUTPUT
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 destination.
Ex-finished products, human services.
FEEDBACK AND CONTROL
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
INFORMATION SYSTEM 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 information system.
INFORMATION SYSTEM RESOURCE
PEOPLE RESOURC
ES
NETWORK RSOURCE
S
DATA RESOURC
ES
SOFTWARE
RESOURCES
HARDWARE
RESOURCES
PEOPLE RESOURCE People are the essential ingredient for the successful operation
of all information system. It includes end users and IS specialist.
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 developers etc.
HARDWARE RESOURCES
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 information.
SOFTWARE RESOURCES
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.
Example: System software Application software procedures
DATA RESOURCES 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.
NETWORK RESOURCES 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: Microcomputer systems Midrange systems Mainframe systems
COMPUTER HARDWARE
MICROCOMPUTER 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 COMPUTERS
Midrange systems are primarily are high-end network servers that can handle the large scale processing of many business applications.
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 network management.
Examples: network servers, minicomputers, web servers and multiuser systems
MAINFRAME COMPUTER SYSTEMS
Mainframe systems are large, fast and powerful computer systems.
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 computers.
PERIPHERALS Peripherals is a generic name given to all input , output and
secondary storage devices that are a part of a computer system.
Peripherals depend on direct connections or telecommunications link to the central processing unit of a computer system .
INPUT TECHNOLOGIES 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 Pointing devices are used for issuing commands , making
choices . 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 graphics tablet.
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 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
STORAGE TRADE-OFFS Computer users depend on memory circuits and secondary
storage devices of computer systems to meet storage requirements.
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 lower capacities.
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 media.
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 bits. 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 memoryo Magnetic diskso Optical diskso 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 follows-
An element of data or instructions can be directly stored and retrieved by selecting and using any of the locations on storage media.
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.
Semiconductor memory
The primary storage of a computer consists of microelectronic semiconductor chips.
It provides with the working storage a computer needs to process applications.
Attractions of semiconductor memory are-o Small sizeo Great speedo Shock resistanceo 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 or overwritten.
Magnetic disks
Magnetic disks are the most common form of secondary storage for a computer system.
They provide fast access and high storage capacities at a reasonable cost.
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 and data.
RAID storage
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 many disks.
They provide a fault-tolerant capacity, in which their redundant design offers multiple copies of data on several disks.
If one disk fails, data can be recovered from backup copies automatically stored on other disks.
MAGNETIC TAPE
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) storage.
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 systems.
OPTICAL DISKS
Optical disk technology has become a necessity. Most software companies now distribute their elephantine programs o CD-ROMs.
It is a fast-growing type of storage media. Examples :- CD-ROM, CD-RW, DVD, DVD-ROM etc.
Business Applications
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 maintained.
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.
RADIO FREQUENCY IDENTIFICTAION 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 organisms.
Using special device called an RIFD reader, RFID allows objects to be labeled and tracked as they move from place to place.
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 active. 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
bar codes.
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 cost savings.
It also presents significant challenges to privacy and security.
example-Chennai air port
