Unit 1: Number System & Information Systems

February 21, 2026

Semester 2
BP205T

Introduction to Number System & Information Systems

Unit 1 introduces the fundamental language of computers – Number Systems. Computers operate in Binary (Base-2). You learn to convert between Binary, Octal, Decimal, and Hexadecimal, and perform Binary Arithmetic. This unit also introduces Information Systems and Software concepts.

Download PDF

Syllabus & Topics

  • 1Number Systems: Introduction and comparison of Binary, Decimal, Octal, and Hexadecimal.
  • 2Conversion: Decimal to Binary, Binary to Decimal.
  • 3Conversion: Decimal to Octal, Octal to Binary, and vice versa.
  • 4Conversion: Decimal to Hexadecimal, Hexadecimal to Binary, and vice versa.
  • 5Binary Arithmetic: Binary Addition.
  • 6Binary Arithmetic: Binary Subtraction using 1’s Complement method.
  • 7Binary Arithmetic: Binary Subtraction using 2’s Complement method.
  • 8Binary Arithmetic: Binary Multiplication and Binary Division.
  • 9Concept of Information Systems and Software: Definition and scope.
  • 10Information gathering, requirement and feasibility analysis.
  • 11Data Flow Diagrams (DFD): Levels of DFD, Symbols.
  • 12Process specifications, Input/Output design.
  • 13Process Life Cycle: Phases (Initiation, Analysis, Design, Implementation, Maintenance).
  • 14Planning and managing an IT project.

Learning Objectives

Convert Numbers: Convert 255 (Decimal) to Binary, Octal, and Hexadecimal.
Binary Subtraction: Subtract 0011 from 1001 using the 2’s complement method.
Draw a DFD: Draw a Level-0 (Context) Data Flow Diagram for a pharmacy billing system.
Explain SDLC: List the phases of the Software Development Life Cycle (SDLC).
Compare Number Systems: Explain why Binary is used inside computers instead of Decimal.

Frequently Asked Questions (FAQs)

Q1. Why do computers use Binary?

Electronic circuits have two stable states: ON (1) and OFF (0). Binary (Base-2) maps perfectly to these two states. Using decimal would require 10 stable voltage levels, which is impractical and unreliable in hardware implementation.

Q2. How to convert Decimal 42 to Binary?

Repeatedly divide by 2 and record the remainders:
42 ÷ 2 = 21 R0
21 ÷ 2 = 10 R1
10 ÷ 2 = 5 R0
5 ÷ 2 = 2 R1
2 ÷ 2 = 1 R0
1 ÷ 2 = 0 R1

Read the remainders from bottom to top → 101010

Q3. What is 2’s Complement?

2’s complement of a binary number = 1’s complement + 1.
It is used to represent negative numbers and to perform subtraction using addition circuits in digital systems.

Q4. What is a Data Flow Diagram (DFD)?

A DFD is a graphical representation that shows how data flows through an information system.
It uses four main symbols:

  • Circle → Process

  • Rectangle → External Entity

  • Arrow → Data Flow

  • Open Rectangle → Data Store

Q5. What are the phases of the Software Development Life Cycle (SDLC)?

The phases are:

  1. Planning

  2. Requirements Analysis

  3. System Design

  4. Implementation (Coding)

  5. Testing

  6. Deployment

  7. Maintenance