Chapter1: Intro to Software Development

COSC 1010 Intro to Software Development

Course Information

  • Instructor: Dr. Md. Tahmidul Islam Molla

  • Department: Computer Science

  • University: Marquette University

  • Copyright: Pearson Education, Inc., 2021, 2018, 2015. All Rights Reserved.

Chapter 1: Introduction to Computers and Programming

Topics Covered

  • Introduction to Computers and Programming

  • Hardware and Software

  • How Computers Store Data

  • How a Program Works

  • Using Python

Introduction

  • Definition of Computers:

    • Computers can be programmed to perform any job as dictated by a program.

  • Definition of Program:

    • A program is defined as a set of instructions that a computer follows to complete a task; commonly known as software.

  • Role of a Programmer:

    • A programmer is an individual who can design, create, and test computer programs; also referred to as a software developer.

How a Program Works

  • CPU and Machine Language:

    • A computer's CPU (Central Processing Unit) can only understand instructions in machine language, which makes it challenging for humans to write entire programs directly in that form.

  • CPU as the Computer's Brain:

    • While commonly referred to as the brain of the computer, the CPU is an electronic device designed to perform specific functions and is not inherently intelligent.

  • Operations Performed by the CPU:

    • Reading data from main memory

    • Performing arithmetic operations:

    • Addition

    • Subtraction

    • Multiplication

    • Division

    • Moving data between memory locations

    • Comparing values (e.g., equality checks)

  • Instruction Role in Computation:

    • The CPU requires a set of instructions (a program) to perform operations.

Hardware and Software

  • Definition of Hardware:

    • Hardware refers to the physical devices that constitute a computer.

  • Components of a Computer System:

    • Central Processing Unit (CPU)

    • Main Memory (RAM): Temporary storage for data and programs during processing.

    • Secondary Storage Devices: Devices where data is held long-term.

    • Input and Output Devices: Components that allow user interaction and display results, respectively.

The CPU

  • Role of the CPU:

    • The CPU is the essential component that runs programs; without it, no software can function.

  • Microprocessors:

    • Modern CPUs, known as microprocessors, are integrated onto small chips, making them compact compared to earlier models.

  • Historical Context:

    • ENIAC: Considered the world’s first programmable electronic computer, built in 1945.

    • It measured 8 feet tall, 100 feet long, and weighed 30 tons, primarily consisting of a large CPU.

Main Memory

  • Definition of Main Memory:

    • Main memory is where a computer stores the active program and the data that the program is manipulating during execution.

  • Terminology:

    • Often referred to as Random Access Memory (RAM).

    • Characteristics of RAM:

    • Quick access for the CPU

    • Volatile (data erased when power is off)

Secondary Storage Devices

  • Definition and Function:

    • Secondary storage retains data for prolonged periods and supplies it to main memory as needed.

  • Types of Secondary Storage:

    • Disk Drives: Use magnetic encoding to store data on circular disks.

    • Solid State Drives (SSD): Faster than disk drives with no moving parts, using solid-state memory.

    • Flash Memory: Portable storage that does not utilize a physical disk.

Input and Output Devices

  • Input Devices:

    • Collect data from users or other devices.

    • Examples: keyboard, mouse, touchscreen, scanner, camera.

    • Disk drives function as input devices by loading programs into RAM.

  • Output Devices:

    • Present data processed by the computer to users or devices.

    • Examples: video displays, printers.

    • Disk drives and USB drives may also function as output devices when saving data.

Software Overview

  • Role of Software:

    • All computer operations are controlled by software, which is divided into two primary categories.

  • Types of Software:

    • Application Software:

    • Software designed for performing everyday tasks such as word processing, email, gaming, and web browsing.

    • System Software:

    • Software that manages basic operations of the computer.

    • Includes operating systems (control of hardware operations), utility programs (perform specific tasks), and software development tools (for creating and testing programs).

How Computers Store Data

  • Binary Numbering System:

    • Fundamental to how electronic machines represent information with clear, unambiguous data storage.

    • Base-10 and Base-2:

    • Humans typically use base-10 (decimal system).

    • Computers utilize base-2 (binary system), which represents data in sequences of 0s and 1s.

Binary Numbering Specifics

  • Representation of Data:

    • Binary principles are characterized as On/Off, Yes/No, True/False, and Positive/Negative, essential for computational reliability.

    • Contents are interpreted by computers to display information in human-readable form.

  • Positional System Comparisons:

    • Base-Ten Example:

    • The decimal number 1,943 can be expressed as:
      (1 imes 10^3) + (9 imes 10^2) + (4 imes 10^1) + (3 imes 10^0)

    • Base-Two Example:

    • The binary number 1101 can be expressed as:
      (1 imes 2^3) + (1 imes 2^2) + (0 imes 2^1) + (1 imes 2^0) = 13

Storing Data Formats

  • Byte Representation:

    • A byte stores memory equivalent to a letter or small number, consisting of eight bits.

    • Bit Definition:

    • A bit is an electrical component that can hold a positive or negative charge – essentially functioning as an on/off switch.

  • Character Encoding:

    • Data characters converted to numeric codes, primarily through ASCII, which encodes a total of 256 characters via 8-bit numbers.

    • Example representations:

    • +5 = 0101, -5 = 1101 using sign/magnitude notation.

  • Unicode Standard:

    • An extensive encoding scheme capable of representing characters from various languages, using a minimum 16-bit system, accommodating 65,536 unique characters.

Advanced Number Storage Techniques

  • Negative Numbers Encoding:

    • Negative integers are represented using two's complement notation.

  • Real Numbers Encoding:

    • Real numbers use floating-point notation for storage.

Other Types of Data Representation

  • Digital Data:

    • Digital devices store information as binary numbers.

    • Images are composed of pixels, and each pixel's color is encoded as a binary number.

    • Audio is represented in sections called samples, also encoded in binary.

Comparisons of Data Storage Requirements

  • Text vs. Audio vs. Images:

    • A typical 300-page novel may contain approximately 4 million bits (based on an estimate of 100,000 words x 5 chars/word x 8 bits/char).

    • Comparatively, 1 minute of audio encoded in MP3 format:

    • (44,100 ext{ samples/sec} imes 16 ext{ bits/sample} imes 60 ext{ sec/minute}) = 42 ext{ million bits}

    • Storage for a single photograph may be:

    • (5,000,000 ext{ pixels/photograph} imes 24 ext{ bits/pixel}) = 120 ext{ million bits}

Hexadecimal Notation

  • Function and Usage:

    • Hexadecimal notation is shorthand for handling long bit patterns, grouping them into four bits for brevity.

    • Example conversion:

    • The binary pattern 10110101 becomes 0xB5 in hexadecimal.

Program Execution Overview

  • Program Flow:

    • The CPU executes programs by fetching instructions from memory, decoding them, and executing relevant operations through a cycle.

  • Fetch-Decode-Execute Cycle:

    • Fetch: Retrieves the next instruction from memory.

    • Decode: Interprets the instruction to determine the required operation.

    • Execute: Carries out the specified operation.

Machine Language to Assembly Language

  • Assembly Language Definition:

    • Assembly language provides mnemonics for instructions, simplifying programming compared to binary.

    • Example syntax:

    • MOV eax, 3

    • MOV ebx, 4

    • ADD eax, ebx

  • Assembler's Role:

    • An assembler converts assembly language into machine language for CPU execution.

High-Level Programming Languages

  • Definition:

    • High-level programming languages allow for simpler and more powerful program creation, requiring minimal knowledge of CPU workings.

    • Example: Python programming language exemplifies high-level language characteristics.

Compilers and Interpreters

  • Compiler Function:

    • A compiler translates high-level language programs into machine code, allowing for execution at any time.

  • Interpreter Function:

    • An interpreter performs real-time translation of high-level instructions, executing one at a time without generating separate machine code.

    • Python employs an interpreter for this purpose.

Programming Basics in Python

  • Installation and Configuration Required:

    • Python must be properly installed, including the Python interpreter.

  • Modes of Operation:

    • Interactive Mode: Users can enter statements directly via command-line input.

    • Script Mode: Users save statements in a file with a .py extension, running it from the operating system command line using python filename.

The IDLE Programming Environment

  • IDLE Definition:

    • Integrated Development Environment (IDLE): An essential tool for writing, executing, and testing Python programs, automatically installed with Python.

  • Interactive Features:

    • Built-in text editor designed to assist in Python programming.

Summary of Chapter 1

  • Main hardware components of computers

  • Types of software

  • Methods for data storage

  • Basic operations of the CPU and machine language

  • The fetch-decode-execute cycle

  • Translation of complex languages to machine code

  • Installation procedures for Python and interpreter modes.

Practice Problems

  1. A(n) _ is a set of instructions that a computer follows to perform a task.

    • a. compiler

    • b. program

    • c. interpreter

    • d. programming language

  2. The physical devices that a computer is made of are referred to as _.

    • a. hardware

    • b. software

    • c. the operating system

    • d. tools

  3. The part of a computer that runs programs is called _.

    • a. RAM

    • b. secondary storage

    • c. main memory

    • d. the CPU

  4. The computer stores a program while the program is running, as well as the data that the program is working with, in _.

    • a. secondary storage

    • b. the CPU

    • c. main memory

    • d. the microprocessor

  5. A byte is made up of eight _.

    • a. CPUs

    • b. instructions

    • c. variables

    • d. bits