Introduction to Computer and Number System
Information Technology Practices in Business
B.Com (CBCS and Non CBCS)
Unit – 3: Introduction to Computer and Number System
Meaning of Computer and
Digital Computer
The term
‘computer’ usually refers to an electronic device made of electronic circuits
which processes data into meaningful information under the control of specific
step-by-step instruction arranged as a program. It performs many functions such
as calculation, storage, manipulation & retrieval of information.
Digital Computer: Digital
computer is the most commonly used type of computers. A computer that performs
calculations and logical operations with quantities represented as digit,
usually in the binary number system. It is used for processing data represented
by discrete, localized physical signals, as the presence or absence of electric
current. In other words, the machine which operates on data, symbols etc. that
are expressed in machine language means in 0 or 1 form are called digital
computers. In today’s world, Apple Macintosh is the best example of digital
computer.
The main three components of
digital computer are,
1.
Input: The user
gives a set of input data.
2.
Processing: The
input data is processed by well defined and finite sequence of steps.
3.
Output: Some data
available from the processing step are output to the user.
The key
characteristics (or advantages) of a computer are:
1.
Speed: The speed
of a computer is usually measured in milliseconds, microseconds, nanoseconds
and picoseconds which are
2.
Accuracy: Errors do
occur in computer based information systems but precious few can be directly
attributed to the computer system itself. The vast majority can be traced to a
program which is mainly human errors.
3.
Capacity
of Decision Making: By suitable programming, computers can also
perform intelligent functions of decision making.
4.
Reliability: The
system does repetitive work with huge volumes of data correctly. One can rely
on them to work non-stop, keeping a back up of data and also an Uninterrupted
Power Supply (UPS).
5.
Memory
Capability: Computer systems have total instant recall of data and an almost
unlimited capacity to store these data. A computer system can hold billion
characters at a time can be retrieved at random.
Advantages of Computer System:
a. Speed: The
smallest unit of time that a human being can experience is second. But Computer
operations are measured in milliseconds, microseconds, nanoseconds and
picoseconds. Today computers can perform more than 2500 MIPS. They can handle
very complex tasks in seconds.
b. Accuracy:
Errors occur in computers also but only few errors can be attributed
(=credited) to a computer. In most of the cases errors occur due to program
logic error, procedural error or erroneous data. Really speaking, these are
human errors.
c.
Reliability: Computers can perform repetitive tasks very well. They don’t take
sick days and coffee breaks and they rarely make any complaints. Even the error
rate of 0.1% is unacceptable.
d. Memory
capability: Computer systems can instantly recall the data and their storage
capacity is almost unlimited. Today, even ordinary personal computers are
coming with 10 to 40 GB of memory. High end computers can support still more
memory.
e.
Flexibility: Modern digital computers can be used for a variety of purposes and
everything depends on the program inside the computer.
f. Choice of
configuration: A wide range of optional peripherals are available in the
market. A business organisation can select those peripherals which are most
suitable for its processing requirements.
Limitations of computer system
The
limitations of compute are as follows:
1)
GIGO: Garbage in
Garbage Out i.e. computer does not have its own IQ and an incorrect input data
would result in an incorrect output. The computer does what it is programmed to
do and can do nothing else.
2)
Limitations
of Software: To perform specialized functions, special software is required.
The investment in software is much more than in hardware.
3)
Tampering
of Data: Data handling through computers require special protection
routines.
4)
Limitations
of Hardware: Smaller computers can perform relatively limited work at a slower
speed. So more investments is to be required for higher speed computers.
Components of
a Computer System
RAM 01101110 01101001 01110010 01100001 4 3 2 CPU 1 0 Input Output ROM 01101001 01000010 Control Unit ALU Registers 01101110 RAM
Secondary Storage (disk)
2. (a) Control
Unit 2. (b)
A.L.U 4.
(a) Primary 4. (b) Secondary
1.
Input:
a)
Entry of program statement & data into a
computer is done by means of an input device.
b)
Keyboard, floppy, disk drives, cartridge tape
device are the various input devices.
c)
All input devices are instruments of
interpretation and communication between people and computer.
2.
CPU:
a)
Is the heart of the computer?
b)
It contains the logic that controls the
calculation doe by the computer.
c)
It is the central processor that makes comparisons,
performs calculations, reads, interprets & controls the execution of the
instructions.
d)
The CPU consists of two separate sub-units –
i.
Control unit
ii.
Arithmetic logic unit.
In the PC, the CPU is connected to a bus; the
bus is a communication device or in other words a connection between various
parts of the computer.
1)
Control
Unit:
a)
Supervises the operations of entire computer,
b)
Acts as a Central Nervous System by
maintaining the order & directing the flow of sequence of operation &
data within the computer,
c)
It selects the program statement from the
storage unit, interprets the statement & sends the appropriate electronic
impulses to Arithmetic/Logic and storage units which carries out the required
operation.
d)
Its basic function is to instruct the input
device, when to start & stop transferring data to output devices.
2)
ALU:
a)
Performs calculation, compares numeric &
Non-numeric values & make decisions.
b)
Data is transferred from the storage unit to
ALU which is again manipulated & returned to storage unit.
3.
Output
Devices:
a)
Are instruments that communicate between users
& machine?
b)
Meant for presenting results.
c)
Translates computer output in user
understandable form.
d)
Printer, VDU, Graph-Plotters are the output
devices.
e)
Captures information in machine coded form
& converts them into a form usable by humans computers.
4.
Storage:
a)
Primary:
Ø
Has no logic capability and is one a storage
unit for data and instruction.
Ø
It is passive in nature. Memory is only a
storage place for information. Instructions are executed in CPU. Data are moved
between the CPU and memory when a calculation is performed.
b)
Secondary:
(Diskette drive, disk etc.)
Ø
Are machines & are connected online to CPU
and serve as reference libraries?
Ø
Used as a store house & used only when
necessary.
Ø
Magnetic tapes, Floppy, H.D. CDS etc. are the
devices.
Ø
Usually larger and cheaper than Primary.
Computer Generations
The computers
have been grouped into chronological categories, called generations. Computer
generation means a step of advancement in technology. It also reflects the
growth of computer industry. The advancement in technology existed not only in
hardware but also in software. The evolution of modern computer is divided in
different generations as below:
1. First
Generation: The first generation of computers was developed in late 1940s. In
this generation of computers, vacuum tubes were used and these were bulky in
size. These computers were very expensive to operate and in addition to using a
great deal of electricity, the first computers generated a lot of heat, which
was often the cause of malfunctions.
First
generation computers relied on machine language, the
lowest-level programming language understood by computers, to perform
operations, and they could only solve one problem at a time. It would take
operators days or even weeks to set-up a new problem. Input was based on
punched cards and paper tape, and output was displayed on printouts.
2. Second
Generation: In the generation of computers, solid state devices called
transistors, diodes etc. were developed by William Shockley and colleagues at
Bell laboratories. These solid state devices were used in place of vacuum
tubes. This replacement increased the speed of computers and other drawbacks
were reduced. Second generation computers were smaller in size, cheaper in
manufacturing. These computers occupied lesser space and consumed lesser power.
3. Third Generation:
These computers have secondary storage devices and new input and output devices
like visual display terminals, magnetic ink readers and high speed printers,
integrated solid state circuit (IC chips). I.C. chips increased the speed of
these computers. These computers performed the arithmetic and logic operations
in micro- seconds (Millionths of a second) or even in nano-second (Billionths
of a second). The size and cost of these computers have decreased considerably.
4. Fourth
Generation: Integrated Circuits Technology was further developed. In 1971,
INTEL Corp. of USA developed the IC chips which have the entire computer
circuit on a single silicon chip. These chips are called microprocessors. These
microprocessors gave birth to micro-computers called micro-processors. In 1976,
Steve Wozniak developed a series of micro-computers called .The Allple Series..
These computers were the most modern computers. These were much cheaper
relative to performance in comparison to early computers.
5. Fifth Generation:
Fifth generation computers are those computers, which not only have the
advanced capabilities like speed, accuracy, storage and retrieval capabilities
of other computers but have also additional ability to think and make
decisions. The ability of intelligence in computers is called Artificial
Intelligence (AI). Japanese have named this generation of computers as KIPS
(Knowledge Information on Processing System).
Different Types of Computers
Since
the advent of the first computer different types and sizes of computers
are offering different services. Computers can be as big as occupying a large
building and as small as a laptop or a microcontroller in mobile
& embedded systems. The four basic types of computers are as under:
a)
Supercomputer
b)
Mainframe Computer
c)
Minicomputer
d)
Microcomputer
a)
Supercomputer: The most powerful computers in terms
of performance and data processing are the Supercomputers. These are
specialized and task specific computers used by large organizations. These
computers are used for research and exploration purposes, like NASA uses
supercomputers for launching space shuttles, controlling them and for space
exploration purpose.
b)
Mainframe computer: Although Mainframes are not as
powerful as supercomputers, but certainly they are quite expensive nonetheless,
and many large firms & government organizations uses Mainframes to run
their business operations. The Mainframe computers can be accommodated in large
air-conditioned rooms because of its size. Super-computers are the fastest
computers with large data storage capacity, Mainframes can also process &
store large amount of data. Banks educational institutions & insurance
companies use mainframe computers to store data about their customers, students
& insurance policy holders.
c)
Minicomputer: Minicomputers are used by small
businesses & firms. Minicomputers are also called as “Midrange Computers”.
These are small machines and can be accommodated on a disk with not as
processing and data storage capabilities as super-computers & Mainframes. These
computers are not designed for a single user. Individual departments of a large
company or organizations use Mini-computers for specific purposes. For example,
a production department can use Mini-computers for monitoring certain
production process.
d)
Microcomputer: Desktop computers, laptops, personal
digital assistant (PDA), tablets & smartphones are all types of
microcomputers. The micro-computers are widely used & the fastest growing
computers. These computers are the cheapest among the other three types of
computers. The Micro-computers are specially designed for general usage like
entertainment, education and work purposes. Well known manufacturers of
Micro-computer are Dell, Apple, Samsung, Sony & Toshiba.
Desktop
computers, Gaming consoles, Sound & Navigation system of a car, Netbooks,
Notebooks, PDA’s, Tablet PC’s, Smartphones, Calculators are all type of
Microcomputers.
Types of memory in a
Computer
1) Primary
memory
2) Secondary
memory
1) Primary
memory: It is directly accessible by the CPU. The primary memory is of two
types such as
a) ROM memory
b) Read only memory
2) Secondary
memory: The maximum capacity of primary memory is limited. So to handle more
data than allowed by primary memory, secondary memory is used. And it is
non-volatile i.e. data is not lost due to current failure. Magnetic tape,
Floppy disk and Hard disk are some examples of secondary memory.
Random Access Memory (RAM)
The memory
system constructed with metal oxide semi conductor storage elements that can be
changed is called Random Access Memory. It is used to hold intermediary data in
the computer. The contents of this memory chips are temporary and can be easily
changed. It is the workspace for the computer’s processor. When people talk
about computer memory, they usually mean volatile memory. It is called random
access memory because access time in RAM is independent of the address of the
data. Each storage location (address) inside the memory is as easy to reach as
any other location and takes the same amount of time. One can reach into the
memory at random and insert or remove numbers in any location at anytime.
Types of RAM:
a. Dynamic
RAM: It is the most common type of main memory. It is dynamic because each
memory cell quickly loses its charge. So it must be refreshed for hundreds of
times each second. In olden days refreshing was done by Microprocessor. Due to
this, lot of processing power was wasted. But today’s dynamic RAM is coming
with built in refresh circuits. This saves lot of processing power.
b. Static
RAM: Static RAM (SRAM) is like DRAM but it is faster, larger and more
expensive. It is static because it is not required to refresh the contents of
RAM continuously. Because of its speed, SRAM is mainly used in special area of
memory called cache memory.
Read Only Memory (ROM)
Another type
of computer memory is Read-Only-Memory (ROM). It is used for storing micro
programs, not available to normal programmers. The information is permanently
stored during manufacturing. The information from the memory can be read but
fresh information cannot be written. Generally ROM is used to store
instructions that are frequently needed, for executing small, extremely basic
operations, which will not be available in the computer’s circuitry.
Different
kinds of ROM:
a. PROM: Programmable
Read Only Memory is a non-volatile memory which allows the user to program the
chip with a PROM writer. User can record any data or instructions. The only
problem with PROM chips is that once data is recorded on them, it cannot be
changed.
b. EPROM: EPROM
stands for Erasable Programmable Read Only Memory. EPROM chips can be
electrically programmed. Unlike ROM and PROM chips, EPROM chips can be erased
and reprogrammed. With the help of ultraviolet light, the data or instructions
on an EPROM chip can be erased and new data can be recorded in its place.
c. EEPROM: It
stands for Electrically Erasable Programmable Read Only Memory. This is the
latest addition to the ROM family of chips. For the purpose of reprogramming,
they need not be removed from the machine. Changes can be made electrically,
under the control of a software.
Software and its Types
Meaning: A
set of instructions (in machine code) given to the computer to solve user
problems and to control different operations of the computer is known as
computer software. The software is developed in programming languages. The
Computer software is classified into two main categories:
1. Application
software.
2. System
software.
1. Application Software: Application Software is the specific that can do
specified application. Application Software is designed to fulfill the
requirement to people. Application Software enables a computer to perform a
specific task such as handling financial accounting, processing words,
preparing exam result, producing bills, manipulating images and videos, etc.
Application Software does its tasks with the help of operating system. There
are two types of Application Software. They are:
a. Packaged Software
b. Customized or Tailored Software
a. Packaged Software: Packaged
Software is the ready made software developed for all general users to perform
their generalized tasks. Software companies use to develop packaged software.
Some commonly used packages are given below:
Word Processing Software: used for
creating documents. Examples: MS-Word, Aldus
PageMaker, Word Perfect, etc.
Electronic Spreadsheet Software: used for
keeping accounts and do calculations. Examples:
MS-Excel, Lotus 1-2-3, etc
Database Management System Software: used for database management. Examples:
MS-Access, Dbase, FoxPro, Sybase, SQL Server, Oracle, etc.
Graphics Software: used for
creating and manipulating images. Examples:
CorelDraw, Paintbrush, PhotoShop etc.
Multimedia Software: used for
designing multimedia. Examples: 3D Max, Maya, Flash,
PowerPoint, Windows Media Player, etc.
b. Customized or Tailored Software: Customized or Tailored Software is the application
software which is designed to fulfill the specific requirements of an
organization, office or individual. Customized or Tailored Software is used for
the organization, office or person for whom it is developed. SLC Result
Processing Software, Hospital Management Software, School Management Software,
Bill Processing Software, Air Ticket Reservation Software, Banking software
etc. customized software. Reservation software, Banking software etc. are
customized software.
2. System
Software: System software is a set of programs that control the operations of a
computer and devices attached with the computer. It creates links between user
and computer as well as controls the execution of application programs. The
examples of system software are:
a) Operating
systems.
b) Sub-routine
c) Device
Drivers.
d) Assemblers
and compilers.
e) Utility
Software
a)
Operating Systems: Operating Systems optimize
man-machine capabilities i.e., the human intervention is minimized. Operating
systems work in multi-programming mode. Multi-programming means interleaved
execution of several programs to enhance the productivity of the computer. The
scheduling for execution of these programs in parts is handled by a special
program known as the supervisory program.
b)
Diagnostic routines are supplied by the
computer manufactures. They assist in debugging the programs by providing a
printout of the contents of the memory upon execution of each instruction
sequentially.
c)
Assemblers / Compilers: These are translation
programs written and supplied by the computer manufacturers and are used to
translate a program written in the source language into the machine language of
the computer on hand.
d)
Sub-routine: A sub-routine is a section of a
main program which is incorporated into the latter, as required to perform a
series of basic instruction. Subroutines are called in from the backing storage
when necessary unless incorporated during program assembly or compilation.
Sub-routines consist of instructions to perform tasks which are common to many
different applications or appear repetitively in the same program and their
inclusion avoids the necessity of writing them and debugging them specially for
each application.
e)
Utility Software: Utility Software is the helpful software that performs specific tasks
related to the maintenance of computer hardware and data. Utility Software
helps to keep a computer in the smooth functioning condition. Utility Software
provides facilities for performing tasks like transferring data and file, recovering
lost data and file, searching and removing computer viruses, disk management
etc. PC Tools, Download Accelerator (DAP), SplitFile, Anti Viruses, WinZip,
WinRaR, Defrag, Norton Disk Doctor (NDD), Register Cleaner, History Cleaner,
Backup Software, Disk tools etc. are some examples of Utility Software.
1.
Antivirus software helps to protect a computer
system from viruses and other harmful programs. A computer virus is a computer
program that can cause damage to a computer's software, hardware or data. It is
referred to as a virus because it has the capability to replicate itself and
hide inside other computer files.
2.
Backup software helps in the creation of a
backup of the files on your computer. Most computer systems use a hard disk
drive for storage. While these are generally very robust, they can fail or
crash, resulting in costly data loss. Backup software helps you copy the most
important files to another storage device, such as an external hard disk.
3.
Disk tools include a range of different tools
to manage hard disk drives and other storage devices. This includes utilities
to scan the hard disks for any potential problems, disk cleaners to remove any
unnecessary files, and disk defragmenters to re-organize file fragments on a
hard disk drive to increase performance. Disk tools are important because a
failure of a hard disk drive can have disastrous consequences. Keeping disks
running efficiently is an important part of overall computer maintenance.
Hardware
Hardware is
best described as a device, such as a hard drive, that is physically
connected to the computer or something that can be physically touched. A
CD-ROM, computer display monitor, printer, and video card are all examples of
computer hardware. Without any hardware, a computer would not function, and
software would have nothing to run on. Hardware and software interact with one
another: software tells hardware which tasks it needs to perform.
Types of Hardware:
Input devices
– keyboard, image scanner, microphone, pointing device, graphics tablet, joystick,
light pen, mouse, touchpad, touchscreen, trackball, webcam
Output
devices – monitor, printer, speakers
Removable
data storage - optical disc drive (CD-RW, DVD+RW), floppy disk, memory card,
USB flash drive
Computer case
- central processing unit (CPU), hard disk, motherboard, network interface
controller, power supply, random-access memory (RAM), sound card, video card
Data ports -
Ethernet firewire, parallel port, serial port, universal serial bus (USB)
There are
several differences between computer hardware and software.
Operating system and Its
types
An operating
system (OS) is software, consisting of programs and data that runs on computers
and manages computer hardware resources and provides common services for
efficient execution of various application software.
Types of
operating systems:
1)
Real-time Operating System: It is a
multitasking operating system that aims at executing real-time applications.
The main object of real-time operating systems is their quick and predictable
response to events.
2)
Multi-user and Single-user Operating Systems:
The operating systems of this type allow a multiple users to access a computer
system concurrently. Time-sharing system can be classified as multi-user
systems as they enable a multiple user access to a computer through the sharing
of time. Single-user operating systems, as opposed to a multi-user operating
system, are usable by a single user at a time.
3)
Multi-tasking and Single-tasking Operating
Systems: When a single program is allowed to run at a time, the system is
grouped under a single-tasking system, while in case the operating system
allows the execution of multiple tasks at one time, it is classified as a
multi-tasking operating system.
4)
Distributed Operating System: An operating
system that manages a group of independent computers and makes them appear to
be a single computer is known as a distributed operating system. The
development of networked computers that could be linked and communicate with
each other, gave rise to distributed computing.
5)
Embedded System: The operating systems
designed for being used in embedded computer systems are known as embedded
operating systems. They are designed to operate on small machines like PDAs
with less autonomy.
Functions
of Operating System: Some of the facilities offered by operating system are
described below:
1)
It communicates with the computer operator by
means of the console unit or typewriter.
2)
In control the flow of jobs by loading and
unloading of programs.
3)
It supervises multi-programming operation
including :
a)
Managing assembly /compilation and execution
of programs.
b)
Allocating control to each program according
to its priority and the operating state of peripheral.
c)
Protecting each program’s working storage from
over-writing by another program.
4)
It undertake errors diagnosis and recovery
techniques in case of error conditions.
5)
It allocates peripherals to programs and
checks their availability.
6)
It warns the operator when peripheral units
require alteration.
7)
It forms an essential element of real-time
system.
8)
It automates the logging of time-relating to
computer operations.
a)
Word Processing.
b)
Firmware.
Meaning of Data and Information
Data: The word “data’ (plural of “datum”) is used generally both in
singular and plural form. Data includes raw materials or facts or observation
about business transactions or physical phenomena that are processed into
finished information products. It is, thus, an objective measurement of
attributes of entities, viz. people, places, things and events. It constitutes
a valuable organizational resource which must be managed efficiently, so that
all end users in an organization are benefitted. Data may be in any of
following forms:
a)
Traditional
alphanumeric data: It is composed of numbers, alphabets and other
characters.
b)
Text data: It
consists of sentences and paragraphs.
c)
Image
data: It consists of graphic shapes and figures.
d)
Audio
data: It consists of human voice and other sounds.
e)
Video
data: It consists of visual image and figures.
Data
are needed to supply required information. Data are treated as raw materials to
furnish finished products in the form of information. Data are viewed by
manager and information systems professionals as data resources which are
typically organized into:
a)
Data bases to hold processed and organized
data.
b)
Knowledge bases to hold knowledge in various
forms.
Information:
Information refers to the data that have been put into a meaningful and useful
context for specific end users. In the words of Davis and Olson, “Information
is data that has been processed into a form that is meaningful to the recipient
and is of real or perceived value in current or progressive decision.”
Information are basic resource and substance on which business decisions are
based. The need for information arises on account of:
a)
Survival
of business: Information is needed for survival of a business.
b)
Basis for
decisions: It is the substance on which business decisions are based.
c)
Framework
for information system: It provides framework for information system
in an organization.
d)
Basis for
various system: It is the finished product which provides basis for various
system in an organization.
Difference between Data and
Information
|
Basic |
Data |
Information |
|
Meaning |
Data
are raw facts or observations or assumptions or occurrence about physical
phenomenon or business transaction. |
It
is the data that has been converted into a meaningful and useful context for
specific end users. |
|
Origin |
They
are objective measurement of attributes (characteristics) of entities (like
people, place, things, and events) |
To
obtain information data’s form is aggregated, manipulated and organized, its
content analyzed & evaluated & placed in proper context for human
use. |
|
Organization |
Data
is a collection of facts, which is unorganized but can be organized into
useful information. |
Information
exists as reports, in a systematic textual format, or as graphics in an
organized manner. |
|
Properties
|
Data
should be accurate but need not be relevant, timely or concise. |
Information
must be relevant, timely accurate, concise and complete and should apply to
the current situation. |
|
Forms
to exist |
It
can exist in different forms e.g. picture, text, sound, or all of these
together. |
It
should be condensed into usable length. |
VARIOUS TYPES OF NUMBER
SYSTEMS
The
knowledge of number systems is very essential because the design and
organization of a computer is dependent upon the number systems. The various number
systems discussed are:
1.
Decimal Number System.
2.
Binary Number System.
3.
Octal Number System.
4.
Hexadecimal Number System.
1.
Decimal
Number System: The decimal number system consists of 10 digits namely 0 to 9. In
decimal system each digit has a digit value from 0 to 9. Each digit also has a
positional value determined by how many places to the left or the right of the
decimal point the digit is written. Digit value and positional value for each
number system depend on the base of the number system. Positional values are in
increasing powers of the base as we move left and decreasing powers of the base
as we move right.
2.
Binary
Number System: Binary numbers play a very important role in design, organization
and understanding of computers. The binary number system, as the name suggests,
consists of two digits namely, 0 and 1 and is exactly like the decimal system
except that the base is 2 instead of 10. Again this code is used only for
mathematical applications and is not intended to handle alphabetic data. Since
the binary system only uses two symbols (1, 0), it called a base-two system.
This means that starting from the low-order position (right-most), successive
positions represent successively higher powers of the base two as we move to
the left (or higher-order position). the reasons why binary numbers are used
for computers are as under:
Ø
Computer circuits have to handle only two
binary digits rather than 10. This simplifies design, reduces cost and improves
reliability.
Ø
Electronic components by their very nature
operate in a binary mode. A switch is either (1) or off (0), or again, a
transistor is either conducting (1) or non-conducting (0).
Ø
Every thing that can be done with the base of
10 can equally be done when the base is 2.
Significance of Binary System
Computers
work on binary system whereas decimal number system is accepted as the
international system. English is taken as the international contact language.
On the other hand, computers understand only binary language i.e. the language
of 0 and 1. In order to talk to computers one has to convert the information,
numeric or non-numeric, into binary language. This is precisely known as Coding.
Coding is the process of representation of numeric or non-numeric information
in terms of binary digits. The process of conversion of numeric quantities into
their binary equivalents has been discussed earlier. By using different bit
patterns the non-numeric information, such as letters of English alphabet A – Z
can be represented. For example, the letter A is represented by the bit
pattern, 110001 and similarly an equal (=) sign is represented as 001011. There
are various codes to represent the data. A few of these are Binary BCD, ASCII
or EBCDIC etc. The details of these codes are discussed below. Coding the
computers is done to achieve the following objectives.
1)
To convert numeric and alphanumeric
information in terms of binary digits 0 and 1.
2)
To transmit correct data to the computer and
also to detect and correct errors, if any, in transmission of data.
3.
Octal
Number System: Since binary numbers are long and cumbersome, more convenient
representations combine groups of three or four bits into octal (base 8) digits
respectively. In octal number, there are only eight possible digits (0 to 7).
The position of a digit to the left of the octal point carries a Weightage in
ascending powers of eight. Digits behind the octal points are also used (octal points
are similar to decimal and binary points are used to separate whole and
fractional parts) and carry Weightage of
4.
Hexadecimal
Number System: The hexadecimal number system popularly known as Hex system is
similar to octal system with the exception that the base is 16 and three must
be 16 digits. This system is very well suited for big computers such as
belonging to IBM (International Business Machines) series or Honeywell etc. The
most commonly used microprocessors having CPU chips as INTEL, 8085 prefer this
number system. The hexadecimal number system represents information in the concise
form. The sixteen symbols used in this system are, decimal digits 0 to 9 and
alphabets A to F. The equivalence between hex-numbers, (numbers represented in
Hexadecimal system) binary and decimal numbers as given below:
|
Decimal
Value |
Hexa
Digits |
Binary
Equivalent |
Decimal
Value |
Hexa
Digit |
Binary
Equivalent |
|
0 1 2 3 4 5 6 7 |
0 1 2 3 4 5 6 7 |
0000 0001 0010 0011 0110 0101 0110 0111 |
8 9 10 11 12 13 14 15 |
8 9 A B C D E F |
1000 1001 1010 1011 1100 1101 1110 1111 |
COMPUTER
CODING SYSTEMS
Computers
work on binary system whereas decimal number system is accepted as the
international system. English is taken as the international contact language.
On the other hand, computers understand only binary language i.e. the language
of 0 and 1. In order to talk to computers one has to convert the information,
numeric or non-numeric, into binary language. This is precisely known as
Coding. Coding is the process of representation of numeric or non-numeric
information in terms of binary digits. The process of conversion of numeric
quantities into their binary equivalents has been discussed earlier. By using
different bit patterns the non-numeric information, such as letters of English
alphabet A – Z can be represented. For example, the letter A is represented by
the bit pattern, 110001 and similarly an equal (=) sign is represented as
001011. There are various codes to represent the data. A few of these are
Binary BCD, ASCII or EBCDIC etc. The details of these codes are discussed
below. Coding the computers is done to achieve the following objectives.
3)
To convert numeric and alphanumeric
information in terms of binary digits 0 and 1.
4)
To transmit correct data to the computer and
also to detect and correct errors, if any, in transmission of data.
Binary Coded
Decimal System (BCD)
BCD
stands for Binary Coded Decimal. For representing decimal number to binary, BCD
codes are used. The appropriate 4 – bit code replaces decimal number in BCD
codes. If in a binary code, number carries certain weight, it is known as
weighted binary code. Nibble refers to a string of 4 bits. By BCD, we mean that
each decimal digit is represented by a nibble. The most leading BCD code is
8421 code, which indicates weight of 4 bits. Although 4 bits can represent 16
numbers (24), only 10 are used and rest 6 are invalid.
The
uses or advantages of BCD code are:
Ø
For representing decimal number to binary, BCD
codes are used.
Ø
BCD code finds its use in pocket calculator,
digital clock, etc.
Ø
BCD codes were used in early version of computer.
The
disadvantages of BCD code are:
Ø
BCD code is slower than binary system.
Ø
BCD code is more complicated than binary
system.
American
Standard Code for Information Interchange (ASCII)
The
computers had started using 8 bits or 1 byte as the standard unit of storage.
By using 6 bits, 2 were not being utilized and their capacity was being wasted.
The computer manufactures, together, developed a 7 bit code and submitted it to
the American National Standards Institute (ANSI) to be issued as a standard code.
This ANSI issued the standard code and decried that every manufacturer shall
have to implement this code on their system.
ASCII
being a 7 bit code offered 128
These
systems have their drawbacks too. Numbers when transmitted use their ASCII values
for the same, which are quite different from their numeric values. Thus,
whenever arithmetic operations have to performed, the numbers have to be
converted to their actual numeric values. The process of conversion is quite
slow when using these codes. To eliminate this problem, IBM developed a code
which assigned hexadecimal values and was very fast in arithmetic operations.
EBCDIC Code: (pronounced
as eb-si-dic) is an eight bit code, known as Extended Binary Coded Decimal
Interchange Code and is widely used. An 8 – bit code permits 256 unique codes
Electronic Data
Processing
Data
processing means transformation of data into more meaningful results for
carrying out scientific, business activities. The result of data processing is
called “information”. The transformation of data consist of a sequence of
operations. The sequence is called “procedure”.
Input ->
Processing -> Output
Data
processing is a system which takes data as an input, carries out the required
processing on the data and produces the information. The system is called
“MANUAL” when processing is performed by human beings and “AUTOMATIC” when
machines are used. When computers are used for data processing the system is
called “Electronic Data Processing”.
Elements of
EDP
There are
five basic elements in a processing system which uses a computer for processing
data. These are hardware, software, user program, procedure and personnels.
1. HARDWARE:
All the physical parts which makes up a computer system called hardware i.e.
all the devices or peripherals which performs the data processing operations.
2. SOFTWARE:
Software consists of programs and routines whose purpose is to make the
computer useable for the user. These software normally supplied by computer
manufacturers or software manufacturers.
3. USER
PROGRAM: A program consist of a related instructions to perform operations. A
data processing job may require a number of programs.
4. PROCEDURE:
The operations of data processing system requires procedure for use, in
preparing data, for operating the computer and distributing the output after
processing.
5.
PERSONNELS: E.D.P basically needs three kinds of skilled personnels.
a) System
Analyst
b) Progammer
c) Operator
a) SYSTEM
ANALYST: System Analyst studies information needs and data processing
requirements, design a data processing system and prepare specification.
b)
PROGRAMMER: A Programmer writes a programmer on specification by System Analyst.
c) OPERATOR:
An Operator is a person who operates the computer system.