Chapter 1: Introduction to Computers, Problem Solving, and Programming Abstraction, and Design using C++ 6e by Frank L. Friedman and Elliot B. Koffman

Algorithms C++ Linux Codewarrior

Early Computers Late 1930’s, John Atanasoff, Clifford Berry ENIAC 1946 University of Pennsylvania J. Presper Eckert and John Mauchley John von Neumann, stored-program concept

Categories of Computers Supercomputers Mainframe Minicomputers Microcomputers

Figure 1.2 (a) Notebook Computer (HP Pavilion dv5©, Courtesy of Hewlett-Packard).   (b) Palmtop Computer (iPhone 3G©, Courtesy of Apple, Inc.) (c) Desktop Computer (iMac©, Courtesy of Apple, Inc.)

Computer Hardware CPU - central processing unit Main Memory Where decisions are made, computations are performed, and input/output requests are delegated Main Memory Stores information being processed by the CPU Secondary Memory (Mass Storage) Stores data and programs

Computer Hardware Input devices Output devices Network connection Allow people to supply information to computers Output devices Allow people to receive information from computers Network connection Modems Ethernet interface

Figure 1.3 Components of a Computer

Memory Stores Types Composed of bits, which are combined into bytes programs operating system applications data Types RAM - volatile ROM Composed of bits, which are combined into bytes

Memory Cells Address Contents -27.2 1 2 354 3 4 0.005 5 6 -26 . . . 1 2 3 4 5 6 . . . 999 -27.2 354 0.005 -26 H RTV 001 . . . X 75.62

Figure 1.5 Relationship Between a Byte and a Bit

Secondary Memory Semi permanent data-storage capability Magnetic Hard disk Floppy disk Tape Non-magnetic CD or DVD memory stick, flash drive Secondary memory usually has much more storage capacity than main memory

Figure 1.6 Secondary Storage Media

CPU “Brains” of the computer Arithmetic calculations are performed using the Arithmetic/Logical Unit or ALU Control unit decodes and executes instructions Registers hold information and instructions for CPU to process Arithmetic operations are performed using binary number system

Figure 1.1 The Intel Atom processor chip contains the full circuitry of a central processing unit in an integrated circuit whose small size and low power requirements make it suitable for use in mobile internet devices. (Intel Corporation Pressroom Photo Archives)

Input / Output Devices Accessories that allow computer to perform specific tasks Receiving information for processing Return the results of processing Common input and output devices Keyboard Joystick Scanner Printer Monitor Speaker

Computer Networks Allows multiple computers to connect together to share resources and/or data LAN - Local area network Organizational WAN - Wide area network Internet Requires additional hardware modem network interface

Figure 1.7 Local Area Network

Figure 1.8 A Wide Area Network with Satellite Relays of Microwave Signals

World Wide Web Introduced 1989 Developed by CERN Web browser European Laboratory for Particle Physics Web browser GUI Netscape IE

1.3 Computer Software Operating system Other system software utilities programming language systems Applications

Operating System E.g. Windows®, Unix® Controls the interaction of system with the user hardware interactions Part is usually stored on ROM, rest on hard drive This arrangement requires booting the system

Some OS Responsibilities Communicating with the user; receiving user commands Managing allocation of memory, processor time, file system, and other resources Collecting input from keyboard, mouse, etc. Conveying output to screen, printer, etc. Writing data to secondary storage devices

Figure 1.9 Entering a UNIX Command for Directory Display

Figure 1.10 Accessing Secondary Storage Devices through Windows

Application Software Does the “real” work Common application software Word processors Desktop publishing programs Spreadsheets Presentation managers Drawing programs

Programming Languages Machine Language Most fundamental language of the computer Unique for each processor type Binary 0s and 1s that specify what to do 0010 0000 0000 0100 1000 0000 0000 0101 0011 0000 0000 0110

Table 1.2 A Program in Machine and Assembly Language

High - Level Languages Resemble human language C++, C, Pascal, FORTRAN, Ada a = a + b; More compact and human understandable than machine language Must be translated into machine language

Object Oriented Programming C++ derived from C by Bjarne Stroustrup Popular because of reuse Classes Objects Methods Organized in a Hierarchy Super Classes Sub Classes

Object Oriented Design Abstraction Extract the relevant properties of an object while ignoring inessential details Encapsulation Breaking down an object into parts, hiding and protecting its essential information, and supplying an interface to modify the information in a controlled and useful manner

1.4 Processing a High-Level Language Program Set of programs used to develop software A key component is a translator Compiler Examples g++, Borland C++®, Microsoft Visual C++® Other programs needed Editor Linker Loader

Processing a Program Editor used to enter the program Like minimal word processor Creates source program file Compiler translates the source program Displays syntax errors Creates (usually) temporary object code file Linker/Loader to combine object file with other object files and execute program Creates final executable program

Executing a Program CPU Special instructions used to examines each program instruction in memory sends out command signals required to carry out the instruction Special instructions used to input data into memory for the program to use output data to display or printer (or other device)

Figure 1.11 Entering, Translating, and Running a High-Level Language Program

Figure 1.12 Flow of Information During Program Execution

1.5 Software Development Method Problem Analysis Identify data objects Determine Input / Output data Constraints on the problem Design Decompose into smaller problems Top-down design (divide and conquer) Develop Algorithm (Desk check) Algorithm refinement

Software Development Method Implementation Converting the algorithm into programming language Testing Verify the program meets requirements System and Unit test Maintenance All programs undergo change over time

1.6 Applying the Software Development Method Case Study: Converting Miles to Kilometers Problem  Your summer surveying job requires you to study some maps that give distances in kilometers and some that use miles. You and your coworkers prefer to deal in metric measurements. Write a program that performs the necessary conversion.

Case Study Analysis  The first step in solving this problem is to determine what you are asked to do. You must convert from one system of measurement to another, but are you supposed to convert from kilometers to miles, or vice versa? The problem states that you prefer to deal in metric measurements, so you must convert distance measurements in miles to kilometers.

Data Requirements Problem Input miles distance in miles Problem Output kms the distance in kilometers Relevant Formula 1 mile = 1.609 kilometers

Design Formulate the algorithm that solves the problem. Algorithm 1. Get the distance in miles. 2. Convert the distance to kilometers. 3. Display the distance in kilometers. Algorithm Refinement 2.1 The distance in kilometers is 1.609 the distance in miles Desk check!

Listing 1.2 Miles to kilometers

Implementation #include <iostream> using namespace std; int main( ) { const float KM_PER_MILE = 1.609; float miles, kms; cout << “Enter the distance in miles: “; cin >> miles; kms = KM_PER_MILE * miles; cout << “The distance in kilometers is “ << kms << endl; return 0; }

Testing Test with input data for which you can easily determine the expected results E.g. 10 miles should convert to 16.09 kilometers

1.7 Professional Ethics for Computer Programmers Privacy and Misuse of Data Computer Hacking Plagiarism and Software Piracy Misuse of a Computer Resource