Computer Systems. Computer Systems COMP1208. Objectives of the Module. Course Assessment. Reading List. What will you need

Transcription

1 Computer Systems Computer Systems Lecturer: Ruth Coffey Room KE-4-027, Today s Lecture >> Module Overview Objectives of Module Course Assessment Reading List Introduction to Computer Systems Slide 1 Slide 2 Objectives of the Module On completion of this module, the learner will be able to: Identify the main elements of a computer system and describe their function Differentiate between different types of computer system. Describe the general structure of a computer system using block diagrams Use flowcharts to describe system processes Outline the function and operation of various types of transducers in simple control systems. Describe the function and operation of ADC s and DAC s in simple computer controlled systems. Develop C++ programs to interface simple data sources to a microcomputer Slide 3 Course Assessment Written examination 50% Laboratory continuous assessment 50% Examination: 2 hours duration Attempt ALL 3 questions Laboratory: 2 hour lab every week - continuous assessment Includes one formal element Slide 4 Recommended Texts Reading List Structured Computer Organization, S. Tanenbaum, Fourth Edition, Prentice-Hall, Inc 2000 Alan Evans, Kendall Martin and Mary Ann Poatsy, Technology in Action-Complete 2/e, Prentice Hall, 2005 Paul Kelly, A Guide to C++ Programming, Gill & MacMillan Ltd. (2001). Deitel & Deitel, C++ How To Program (3rd Edition.) What will you need Lectures Course notes are provided by lecturer Paper and pen for additional note taking Laboratory Lab exercise sheets - provided by lecturer Lab Folder Course notes Reference text Slide 5 Slide 6

2 What is a Computer? Computer A device capable of performing computations and making logical decisions Review Fundamentals from Semester 1 Computer programs Sets of instructions that control a computer s processing of data Hardware Overview of a Computer System Bits and Bytes Number Systems Various devices comprising a computer Examples: keyboard, screen, mouse, disks, memory, CD-ROM, and processing units Software Programs that run a computer Slide 7 Computer System Organisation Slide 8 Computer System - main elements Microcomputer System Secondary Storage Main Memory (ROM and RAM) Central Processing Unit (CPU) - data processing and control Main Memory (primary storage) - stores data Secondary Storage - stores permanent data Input and Output (I/O) devices - moves data between the computer and its external environment System interconnection - provides mechanism for communication among various components Output Devices Printer Microprocessor (ALU + CU) Input Devices Output to printer -Tape -Disc -Teleprinter -Data from transducers I/O Unit Output to VDU Input from keyboard Visual Display Unit (VDU) Keyboard Slide 9 Computer Hardware Input Devices Input devices System unit Output devices Storage devices Enter data to be processed Text Images Sound D A C B The ra Slide 10 in in S pain Slide 11 Slide 12 2

3 System Unit Output Devices Processes data into usable information Enable us to see or hear the processed information System Unit Speaker CPU Motherboard Memory Module Monitor Printer Slide 13 Storage Devices Slide 14 Types of Computers Enable us to store data or information to be accessed again Floppy Disk Drive Hard Disk Drive CD / DVD Drive Type Example Application Disposable computer Greeting cards Microcontroller Watches, cars, appliances Game Computer Home Video games Personal Computer (PC) Desktop or notebook computer Server Network server Collection of Workstations Departmental mini-supercomputer Mainframe Batch data processing in a bank Flash Drive Slide 15 Specialty Computers Slide 16 System software Server PDA Server Mainframe Supercomputer PDA System software contains programs that perform tasks essential to the efficient functioning of Application Software computer hardware. System Software Computer Hardware Mainframe Supercomputer Slide 17 Slide 18 3

4 Computer Software Computer Platforms: PCs and Macs Programs that enable the computer to perform different tasks System software Application software PC CPU Intel, AMD Operating system Microsoft Windows Mac CPU Motorola Operating system Apple Mac OS Slide 19 Slide 20 System Software The Operating System controls the computer s use of its hardware resources such as memory and disk storage space. Utilities are designed to augment the operating system by providing a way for a computer user to control the allocation and use of hardware resources. Disk Drivers used to control the peripheral devices Computer Programming Languages allow the user to write his/her own software programs to perform specific tasks. Bits and Bytes The language of computers!! Slide 21 Slide 22 Bit Binary digit 0 or 1 Byte Eight bits Bits and Bytes: Microchip Switch OFF ON Represent letters, numbers, and special characters 01 MSB and LSB MSB -> most significant bit LSB -> least significant bit = ASCII code for 4 MSB LSB = ASCII code for A 0 Slide 23 Slide 24

5 Representing Data in Binary Information is encoded in bit strings 2 n different strings possible, where n is the length of string such information includes characters, numbers, images, sound, machine language instructions, etc 4-Byte Word -> 4 x 8 bits = 32 bit word e.g, NAME Byte Kilobyte Megabyte Gigabyte Terabyte Petabyte MB GB TB PB How Much is a Byte? ABBREVIATION B KB NUMBER OF BYTES 1 byte 1,024 bytes 1,048,576 bytes 1,073,741,824 bytes 1,099,511,627,776 bytes 1,125,899,906,842,62 4 bytes RELATIVE SIZE Can hold one character of data. Can hold 1,024 characters or about half of a typewritten page doublespaced. A floppy disk holds approximately 1.4 MB of data, or approximately 768 pages of typed text. Approximately 786,432 pages of text. Since 500 sheets of paper is approximately 2 inches, this represents a stack of paper 262 feet high. This represents a stack of typewritten pages almost 51 miles high. The stack of pages is now 52,000 miles high, or about one-fourth the distance from the Earth to the moon. Slide 25 Slide 26 NUMBER SYSTEMS Most Common Decimal (10 digits) Binary (2 digits) Hexadecimal (16 digits) Less frequently used Octal (8 digits) Trinary (3 digits) For example: Example = (4/10) + (5/100) = (1 * 10 2 ) + (2 * 10 1 ) + (3 * 10 0 ) + (4 * 10-1 ) + (5 * 10-2 ) Note, a number with a subscript of 10 (i.e. Base 10) indicates that this is a decimal number. However, decimal is the default number system, so usually the subscript is not included for decimal numbers. Slide 27 Slide 28 Binary Number System Binary system has 2 symbols: 0 and 1 Subscript 2 is used to indicate that a number is binary,for example, 10 2 Binary digits are weighted like the decimal system according to their position 2 n n Binary point Slide 29 Decimal Binary Table COUNT DECIMAL BINARY zero 0 02 one 1 12 two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen With n-bits => can count from 0 to 2 n -1 3 bits -> 0 to => 0 to 7 4 bits -> 0 to => 0 to 15 Slide 30

6 C++ Bitwise Operators Bit Masking AND (&) result is 1 only if both inputs are 1 0 & 0 = 0 0 & 1 = 0 1 & 0 = 0 1 & 1 = 1 OR ( ) result is 1 only if ANY inputs are = = = = 1 XOR (^) result is 1 if inputs are different 0 ^ 0 = 0 0 ^ 1 = 1 1 ^ 0 = 1 1 ^ 1 = 0 Can set one or more bits in a data item to the value one using the logical OR operator. To set a bit, first a mask is used where the mask has a bit set to 1 in the same position as the bit in the data item we require to be set, all other bits are zero Similarly it is possible to clear a bit, i.e. set it to zero, using the logical AND operator. To clear a bit, a MASK is used in where the mask has a bit set to 0 in the same position as the bit the data that is to be cleared, all other bits in the mask are set to 1. XOR can be used to invert selected bits using a mask Slide 31 Slide 32 1 s Complement of Binary Numbers The 1 s Complement of Binary Numbers is found by changing all 1s to 0s and all 0s to 1s: For example 1: Binary Number s complement For example 2: Binary Number s complement 2 s Complement of a Binary Number 2 s Complement of Binary Numbers is found by adding 1 to the LSB of the 1 s complement: 2 s complement = 1 s complement + 1 For Example: Binary Number s complement Add s complement Slide 33 Slide 34 Hexadecimal Numbers COUNT DECIMAL BINARY HEXADECIMAL. zero one two three four five six seven eight nine ten A 16 eleven B16 twelve C16 thirteen D16 fourteen E16 fifteen F 16 Based on sixteen symbols: (0,1,2,3,4,5,6,7,8,9,,A,B,C,D,E,F) Convenient way of expressing binary number and codes and is frequently used in conjunction with microprocessors and computers. The subscript 16 is used to indicate that a number is Hexadecimal, for example, In C++ programming the prefix 0x is used to indicate that a number is Hexadecimal, for example 0xFF is the hexadecimal of 255. Slide 35 Hex! Binary Binary to Hexadecimal conversion Convert the binary number to Hex =39816 Hexadecimal to Binary conversion Convert the Hexadecimal number D2E 16 to a binary number. D 2 E D2E16 = Break into groups of 4 bits Work out from the binary point Convert each decimal digit to equivalent 4 bits in binary Slide 36

7 Hex to Decimal conversion Convert the Hexadecimal number B2F816 to a Decimal number. 2 0 Hexadecimal (HEX) B 2 F 816 Decimal equivalent HEX Weight * 16 0 = 8 15 * 16 1 = * 16 2 = * 16 3 = Sum = B2F816 = Decimal to Hex Convert the Decimal number 650 into a Hexadecimal number )650 Hex remainder r = A LSD (least significant digit) 2 16) r = )2 0 2 r = 2 MSD (most significant digit) = 28A16 Slide 37 Slide 38 C++ Code Examples: Display Hex int number=0; cout << "Please enter a number between 0 and 255: "; cin >> number; cout << "The number in decimal is " << number <<endl; cout << "The number in hexadecimal is 0x" << hex << number << endl; C++ Code Examples: Input Hex int number=0; cout << "Please enter a hex number: "; cin >> hex >> number; cout << "The number in decimal is " << number <<endl; Slide 39 Slide 40 Bitwise AND (& operator) result is 1 only if both inputs are 1 0 & 0 = 0 0 & 1 = 0 1 & 0 = 0 1 & 1 = 1 Example Use to check if a bit is set int b = 50; // 50 = 0x32 = b if ( b & 0x01 ) // 0x01 = b cout << "Bit0 is set" << endl; else cout << "Bit0 is not set" << endl; Bitwise OR ( operator) result is 1 only if ANY inputs are = = = = 1 Example Use to ensure a bit is set int b = 50; // 50 = 0x32 = b int c = b 0x04 ) // 0x04 = b cout << "c = " << c << endl; // c = 0x32 0x04 = b bit2 is now set Slide 41 Slide 42

8 Bitwise XOR (^ operator) result is 1 if inputs are different 0 ^ 0 = 0 0 ^ 1 = 1 1 ^ 0 = 1 1 ^ 1 = 0 Example Use to toggle certain bits int b = 50; // 50 = 0x32 = b cout << "b = " << b << endl; b = b ^ 0x18 // 0x18 = b cout << "b = " << b << endl; // 0x32 ^ 0x18 = b //(bit3 and bit4 toggled) Slide 43