CS 121 - Chapter 1

Chapter 1: Overview of Computers and Programming Languages

Introduction

Software is crucial for the functionality of computers; without it, computers are essentially non-functional tools that cannot perform any tasks. Software can be classified as system software and application software, each serving distinct roles in computer operation.C++ is a versatile and powerful programming language widely used for various applications ranging from system software to game development, making it a fundamental skill for aspiring programmers.

Objectives 1 of 2

• Understand the different types of computers, including categories such as mainframe, microcomputers, and embedded systems, each tailored for specific tasks and performance needs.

• Explore the hardware and software components of a computer system to understand their interactions and contributions to overall performance.

• Learn the fundamental programming languages of computers to gain insights into how software communicates with hardware.

• Trace the evolution of programming languages from machine languages through assembly languages to high-level languages, noting key milestones and developments.

• Examine high-level programming languages such as Python, Java, and their role in modern computing environments.

• Discover the role of compilers as translators of high-level programming languages into machine code, facilitating the execution of software on hardware.

Objectives 2 of 2

• Analyze the structure and syntax of a C++ program, including components such as variables, data types, control structures, and functions.

• Investigate how C++ programs are processed, covering the compilation, linking, and execution phases of program development.

• Understand algorithms and problem-solving techniques, emphasizing the importance of logical thinking and structured approaches to programming challenges.

• Get acquainted with structured programming and object-oriented programming methodologies, including concepts like classes, objects, inheritance, encapsulation, and polymorphism.

• Familiarize with current C++ standards, including Standard C++, ANSI/ISO Standard C++, C++11, C++14, and their features that enhance programming capabilities and efficiency.

A Brief Overview of the History of Computers

Early Calculation Devices

Historical devices such as the Abacus, Pascaline, and the Leibniz device represent the dawn of computational devices, laying the groundwork for future innovations.Charles Babbage's design of the difference engine and analytic engine symbolizes early concepts of modern computing, introducing programmable functions.

Early Computer-like Machines

Computers such as the Mark I and ENIAC mark significant steps towards modern computing systems. Their design utilized the Von Neumann architecture, which established a foundational blueprint for computer organization. The development of transistors and microprocessors revolutionized computational power and efficiency, leading to the miniaturization of hardware components.

Categories of Computers

Computers are classified into categories based on their capabilities and intended usage:

• Mainframe Computers: Large, powerful systems used primarily by large organizations for bulk data processing.

• Midsize Computers: Often referred to as minicomputers, these systems are smaller than mainframes and are used in more modest tasks, often in academic and research environments.

• Microcomputers (PCs): Standard personal computers designed for individual use, encompassing desktops, laptops, and tablets.

Elements of a Computer System

Main Components:

1. Hardware: Physical components of the computer system.

2. Software: Programs and applications that instruct the hardware what to do.

Hardware Overview

Key Components:

• Central Processing Unit (CPU): The 'brain' of the computer. It performs arithmetic calculations and logical decision-making, acting as the highest cost driver in computer systems due to its complexity and performance capability.

• Main Memory (RAM): Short-term, volatile storage that temporarily holds data and programs during active processing, allowing for fast access by the CPU.

• Secondary Storage: Non-volatile, long-term storage options such as hard drives, SSDs, and flash drives that retain data even when powered off.

• Input/Output Devices: Interfaces that facilitate interaction with the computer, including keyboards, mice, monitors, and printers.

Central Processing Unit and Main Memory

The CPU operates as the central hub, executing instructions and processing data. All data must reside in RAM during manipulation, holding data temporarily, thus risking loss upon poweroff.Main memory consists of sequential memory cells, each uniquely addressable to facilitate organization and retrieval.

Secondary Storage

Definition: Provides permanent data and program storage essential for long-term data retention.Examples: Hard disks, SSDs, USB drives, and optical disks like CD-ROMs, which serve various roles in data storage and accessibility.

Input/Output Devices

Input Devices: Include peripherals like keyboards, mice, scanners, and cameras, which allow users to input data into the computer.Output Devices: Include monitors, printers, and secondary storage options that provide users with the results of processing tasks.

Understanding Software

Types of Software:

• System Programs: Facilitate hardware management and system functionality, including operating systems like Windows, macOS, and Linux.

• Application Programs: Software designed to perform specific user-based tasks such as word processing, spreadsheets, and graphic design applications.

The Language of a Computer

Types of Signals

• Analog Signals: Represents information as continuously varying signals.

• Digital Signals: Represents information as discrete binary values (0s and 1s), which form the basis of digital computing.

Machine Language

The lowest level of programming; machine language consists purely of binary code that the CPU executes directly.Bit: The fundamental unit of data represented as either 0 or 1.Byte: Consists of 8 bits and serves as a basic unit for data storage measurement.

Number Systems

• Binary System: The primary numeral system used by computers, composed entirely of 0s and 1s.

• Decimal System: The numeral system used in everyday life, based on base 10, incorporating numbers from 0 to 9.

The Evolution of Programming Languages

Early Programming

The initial programming involved writing in machine language, which is complex and error-prone. The introduction of assembly language, utilizing mnemonic codes, simplified programming to a degree by allowing programmers to use symbolic representations for operations and addresses.

High-Level Languages

High-level languages like C, C++, and Java emerged, allowing developers to write more readable and maintainable code. These languages require compilers that translate the high-level instructions into machine-readable code, enabling execution.

Processing a C++ Program

Creating a C++ program involves using text editors to draft source code containing preprocessor directives to manage the development process. The compilation process verifies the code for correctness and translates it into machine code, preparing it for execution. Integrated Development Environments (IDEs) streamline this process by combining editing, compiling, and debugging in one platform.

Programming Methodologies

Structured Programming

An approach that divides problems into smaller, manageable parts, often employing top-down design principles and stepwise refinement for clarity and efficiency.

Object-Oriented Programming (OOD)

A paradigm that centers on identifying and modeling objects and their interactions within a system. Objects encapsulate data and functions, facilitating code reuse and modularity. C++ is designed specifically for supporting OOD principles, enabling a more modern and scalable approach to software development.

Quick Review

A computer functions as an electronic device capable of executing arithmetic and logical operations, significantly enhanced by both hardware and software components. The CPU serves as the central processing unit or 'brain,' working in conjunction with volatile primary storage (RAM) and stable secondary storage solutions (hard disks, SSDs).Algorithms provide a structured approach to problem-solving, with structured design techniques breaking down challenges into subproblems, while object-oriented design focuses on the interactions among objects and classes within the software framework.