Number System
When we type some letters or words, the computer translates them in numbers as computers can understand only numbers. A computer can understand the positional number system where there are only a few symbols called digits and these symbols represent different values depending on the position they occupy in the number.
The value of each digit in a number can be determined using −
The digit
The position of the digit in the number
The base of the number system (where the base is defined as the total number of digits available in the number system)
Decimal Number System
The number system that we use in our day-to-day life is the decimal number system. Decimal number system has base 10 as it uses 10 digits from 0 to 9. In decimal number system, the successive positions to the left of the decimal point represent units, tens, hundreds, thousands, and so on.
Each position represents a specific power of the base (10). For example, the decimal number 1234 consists of the digit 4 in the units position, 3 in the tens position, 2 in the hundreds position, and 1 in the thousands position. Its value can be written as
(1 x 1000)+ (2 x 100)+ (3 x 10)+ (4 x l) (1 x 103)+ (2 x 102)+ (3 x 101)+ (4 x l00) 1000 + 200 + 30 + 4 1234
As a computer programmer or an IT professional, you should understand the following number systems which are frequently used in computers.
| S.No. | Number System and Description |
|---|---|
| 1 | Binary Number System Base 2. Digits used : 0, 1 |
| 2 | Octal Number System Base 8. Digits used : 0 to 7 |
| 3 | Hexa Decimal Number System Base 16. Digits used: 0 to 9, Letters used : A- F |
Binary Number System
Characteristics of the binary number system are as follows −
Uses two digits, 0 and 1
Also called as base 2 number system
Each position in a binary number represents a 0 power of the base (2). Example 20
Last position in a binary number represents a x power of the base (2). Example 2x where x represents the last position - 1.
Example
Binary Number: 101012
Calculating Decimal Equivalent −
| Step | Binary Number | Decimal Number |
|---|---|---|
| Step 1 | 101012 | ((1 x 24) + (0 x 23) + (1 x 22) + (0 x 21) + (1 x 20))10 |
| Step 2 | 101012 | (16 + 0 + 4 + 0 + 1)10 |
| Step 3 | 101012 | 2110 |
Note − 101012 is normally written as 10101.
Octal Number System
Characteristics of the octal number system are as follows −
Uses eight digits, 0,1,2,3,4,5,6,7
Also called as base 8 number system
Each position in an octal number represents a 0 power of the base (8). Example 80
Last position in an octal number represents a x power of the base (8). Example 8x where x represents the last position - 1
Example
Octal Number: 125708
Calculating Decimal Equivalent −
| Step | Octal Number | Decimal Number |
|---|---|---|
| Step 1 | 125708 | ((1 x 84) + (2 x 83) + (5 x 82) + (7 x 81) + (0 x 80))10 |
| Step 2 | 125708 | (4096 + 1024 + 320 + 56 + 0)10 |
| Step 3 | 125708 | 549610 |
Note − 125708 is normally written as 12570.
Hexadecimal Number System
Characteristics of hexadecimal number system are as follows −
Uses 10 digits and 6 letters, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F
Letters represent the numbers starting from 10. A = 10. B = 11, C = 12, D = 13, E = 14, F = 15
Also called as base 16 number system
Each position in a hexadecimal number represents a 0 power of the base (16). Example, 160
Last position in a hexadecimal number represents a x power of the base (16). Example 16x where x represents the last position - 1
Example
Hexadecimal Number: 19FDE16
Calculating Decimal Equivalent −
| Step | Binary Number | Decimal Number |
|---|---|---|
| Step 1 | 19FDE16 | ((1 x 164) + (9 x 163) + (F x 162) + (D x 161) + (E x 160))10 |
| Step 2 | 19FDE16 | ((1 x 164) + (9 x 163) + (15 x 162) + (13 x 161) + (14 x 160))10 |
| Step 3 | 19FDE16 | (65536+ 36864 + 3840 + 208 + 14)10 |
| Step 4 | 19FDE16 | 10646210 |
Number Conversion
There are many methods or techniques which can be used to convert numbers from one base to another. In this chapter, we'll demonstrate the following −
- Decimal to Other Base System
- Other Base System to Decimal
- Other Base System to Non-Decimal
- Shortcut method - Binary to Octal
- Shortcut method - Octal to Binary
- Shortcut method - Binary to Hexadecimal
- Shortcut method - Hexadecimal to Binary
Decimal to Other Base System
Step 1 − Divide the decimal number to be converted by the value of the new base.
Step 2 − Get the remainder from Step 1 as the rightmost digit (least significant digit) of the new base number.
Step 3 − Divide the quotient of the previous divide by the new base.
Step 4 − Record the remainder from Step 3 as the next digit (to the left) of the new base number.
Repeat Steps 3 and 4, getting remainders from right to left, until the quotient becomes zero in Step 3.
The last remainder thus obtained will be the Most Significant Digit (MSD) of the new base number.
Example
Decimal Number: 2910
Calculating Binary Equivalent −
| Step | Operation | Result | Remainder |
|---|---|---|---|
| Step 1 | 29 / 2 | 14 | 1 |
| Step 2 | 14 / 2 | 7 | 0 |
| Step 3 | 7 / 2 | 3 | 1 |
| Step 4 | 3 / 2 | 1 | 1 |
| Step 5 | 1 / 2 | 0 | 1 |
As mentioned in Steps 2 and 4, the remainders have to be arranged in the reverse order so that the first remainder becomes the Least Significant Digit (LSD) and the last remainder becomes the Most Significant Digit (MSD).
Decimal Number : 2910 = Binary Number : 111012.
Other Base System to Decimal System
Step 1 − Determine the column (positional) value of each digit (this depends on the position of the digit and the base of the number system).
Step 2 − Multiply the obtained column values (in Step 1) by the digits in the corresponding columns.
Step 3 − Sum the products calculated in Step 2. The total is the equivalent value in decimal.
Example
Binary Number: 111012
Calculating Decimal Equivalent −
| Step | Binary Number | Decimal Number |
|---|---|---|
| Step 1 | 111012 | ((1 x 24) + (1 x 23) + (1 x 22) + (0 x 21) + (1 x 20))10 |
| Step 2 | 111012 | (16 + 8 + 4 + 0 + 1)10 |
| Step 3 | 111012 | 2910 |
Binary Number : 111012 = Decimal Number : 2910
Other Base System to Non-Decimal System
Step 1 − Convert the original number to a decimal number (base 10).
Step 2 − Convert the decimal number so obtained to the new base number.
Example
Octal Number : 258
Calculating Binary Equivalent −
Step 1 - Convert to Decimal
| Step | Octal Number | Decimal Number |
|---|---|---|
| Step 1 | 258 | ((2 x 81) + (5 x 80))10 |
| Step 2 | 258 | (16 + 5)10 |
| Step 3 | 258 | 2110 |
Octal Number : 258 = Decimal Number : 2110
Step 2 - Convert Decimal to Binary
| Step | Operation | Result | Remainder |
|---|---|---|---|
| Step 1 | 21 / 2 | 10 | 1 |
| Step 2 | 10 / 2 | 5 | 0 |
| Step 3 | 5 / 2 | 2 | 1 |
| Step 4 | 2 / 2 | 1 | 0 |
| Step 5 | 1 / 2 | 0 | 1 |
Decimal Number : 2110 = Binary Number : 101012
Octal Number : 258 = Binary Number : 101012
Shortcut Method ─ Binary to Octal
Step 1 − Divide the binary digits into groups of three (starting from the right).
Step 2 − Convert each group of three binary digits to one octal digit.
Example
Binary Number : 101012
Calculating Octal Equivalent −
| Step | Binary Number | Octal Number |
|---|---|---|
| Step 1 | 101012 | 010 101 |
| Step 2 | 101012 | 28 58 |
| Step 3 | 101012 | 258 |
Binary Number : 101012 = Octal Number : 258
Shortcut Method ─ Octal to Binary
Step 1 − Convert each octal digit to a 3-digit binary number (the octal digits may be treated as decimal for this conversion).
Step 2 − Combine all the resulting binary groups (of 3 digits each) into a single binary number.
Example
Octal Number : 258
Calculating Binary Equivalent −
| Step | Octal Number | Binary Number |
|---|---|---|
| Step 1 | 258 | 210 510 |
| Step 2 | 258 | 0102 1012 |
| Step 3 | 258 | 0101012 |
Octal Number : 258 = Binary Number : 101012
Shortcut Method ─ Binary to Hexadecimal
Step 1 − Divide the binary digits into groups of four (starting from the right).
Step 2 − Convert each group of four binary digits to one hexadecimal symbol.
Example
Binary Number : 101012
Calculating hexadecimal Equivalent −
| Step | Binary Number | Hexadecimal Number |
|---|---|---|
| Step 1 | 101012 | 0001 0101 |
| Step 2 | 101012 | 110 510 |
| Step 3 | 101012 | 1516 |
Binary Number : 101012 = Hexadecimal Number : 1516
Shortcut Method - Hexadecimal to Binary
Step 1 − Convert each hexadecimal digit to a 4-digit binary number (the hexadecimal digits may be treated as decimal for this conversion).
Step 2 − Combine all the resulting binary groups (of 4 digits each) into a single binary number.
Example
Hexadecimal Number : 1516
Calculating Binary Equivalent −
| Step | Hexadecimal Number | Binary Number |
|---|---|---|
| Step 1 | 1516 | 110 510 |
| Step 2 | 1516 | 00012 01012 |
| Step 3 | 1516 | 000101012 |
Hexadecimal Number : 1516 = Binary Number : 101012
Information system
Information systems (IS)
are formal, sociotechnical, organizational systems designed to collect, process, store, and distribute information. In a sociotechnical perspective, information systems are composed by four components: task, people, structure (or roles), and technology.
The six components that must
come together in order to produce an information system are: (Information systems are organizational procedures and do not need a
computer or software, this data is erroneous)
1.
Hardware: The term hardware refers to machinery. This
category includes the computer
itself, which is often referred to as the central processing unit (CPU),
and all of its support
equipment. Among the support, equipment
are input and output devices, storage
devices and communications devices.
2. Software: The term software
refers to computer programs and the manuals (if any) that support
them. Computer programs
are machine-readable instructions that direct the circuitry within
the hardware parts of
the system to function
in ways that produce useful information from data. Programs are generally
stored on some input/output medium,
often a disk or tape.
3.
Data: Data are facts that are used by programs to
produce useful information. Like programs, data are generally stored in machine-
readable form on disk or tape until the computer needs them.
4.
Procedures: Procedures are the policies that govern the
operation of a computer system.
“Procedures are to people
what software is to hardware” is a common
analogy that is used to illustrate the role of procedures in a system.
5.
People: Every system needs people if it is to be
useful. Often the most overlooked element
of the system are the people, probably
the component that
most influence the success or failure of information systems. This
includes “not only the users, but
those who operate and service the computers, those who maintain the data, and those
who support the network
of computers.”
6.
Feedback: it is another component of the IS, that defines
that an IS may be provided with a feedback
Data is the bridge between
hardware and people. This means that the data we collect is only data until we involve people.
At that point,
data is now information.
Types of information system
Some examples of such systems
are:
·
enterprise resource planning
·
geographic information system
Systems Development Life Cycle
An effective
System Development Life Cycle (SDLC) should result in a high quality
system that meets customer expectations, reaches completion within
time and cost
evaluations, and works effectively and efficiently in the current
and planned Information Technology infrastructure.
System Development Life Cycle (SDLC) is a conceptual model which includes policies
and procedures for developing or altering systems
throughout their life cycles.
SDLC is used by analysts to develop an information system.
SDLC includes the following activities –
·
requirements
·
design
·
implementation
·
testing
·
deployment
·
operations
maintenance
Components Of Information System
An Information system is a combination of hardware and software and telecommunication networks that people
build to collect, create and distribute useful
data, typically in an organisational, It defines the flow of information
within the system. The objective of
an information system is to provide appropriate information to the user, to gather the data,
processing of the data and communicate information to the user of the system.
1. Computer Hardware:
Physical equipment used for
input, output and processing. What hardware to use it depends upon the type and size of the organisation. It consists
of input, an output device, operating system, processor, and media devices.
This also includes
computer peripheral devices.
2.
Computer Software:
The programs/
application program used to control and coordinate the hardware components. It is used for analysing and
processing of the data. These programs include a set of instruction used for processing information.
Software
is further classified into 3 types:
1.
System Software
2.
Application Software
3.
Procedures
3. Databases:
Data are the raw facts
and figures that are unorganised that are and later processed
to generate information.
Softwares are used for organising and serving data to the user, managing physical storage of media and virtual resources. As the hardwarecan’twork withoutsoftwarethesameas software needs data for processing. Data are managed
using Database management system.
Database software is used for efficient
access for required
data, and to manage knowledge bases.
4.
Network:
·
Networks resources refer to the telecommunication networks like the
intranet, extranetand the internet.
·
These resources facilitate the flow of information in the organisation.
·
Networks consists of both the physicals devises such
as networks cards, routers, hubs and cables and software
such as operating systems, web servers, data servers and application
servers.
·
Telecommunications networks consist
of computers, communications processors, and other devices interconnected by communications
media and controlled by software.
·
Networks include communication media, and Network
Support.
1. Human Resources:
It is associated with the manpower
required to run and manage the system.
People are the end user of the information system,
end-user use information produced for their own purpose,
the main purpose
of the information system is to benefit the end user.
The end user can be accountants, engineers, salespersons, customers, clerks, or managers etc. People are also responsible to develop and operate information systems. They include systems analysts, computer operators, programmers, and other clerical IS personnel, and managerial techniques
Project management
Project management is the application of processes, methods, skills,
knowledge and experience to achieve specific
project objectives according to the project
acceptance criteria within agreed parameters.
What is a project?
A project is a unique, transient
endeavour, undertaken to achieve planned objectives, which could be defined in terms of outputs, outcomes
or benefits. A project is usually deemed to be a success if it achieves
the objectives according to their acceptance
criteria, within an agreed timescale and budget. Time, cost and quality
are the building blocks
of every project.
Time: scheduling is a collection of techniques used to develop and present schedules that show when work will be performed.
Cost: how are necessary funds acquired and finances managed?
Quality: how will fitness for purpose of the deliverables and management processes
be assured?
The core components of project
management are:
·
defining the reason
why a project is necessary;
·
capturing project requirements, specifying quality of the deliverables, estimating resources and timescales;
·
preparing a business
case to justify
the investment;
·
securing corporate agreement
and funding;
·
developing and implementing a management plan for the project;
·
leading and motivating the project delivery
team;
·
managing the risks, issues and changes on the project;
·
monitoring progress against plan;
·
managing the project
budget;
·
maintaining communications with stakeholders and the project
organisation;
·
provider management;
·
closing the project
in a controlled fashion when appropriate
