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Basics of Computer Systems

Learn the fundamentals of computer systems, including hardware and software components, different types of software, operating systems, mainframe and personal computers, and the birth of the internet.

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Basics of Computer Systems

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  1. Chapter 1 Information Technology Basics

  2. Computer Systems • A computer system consists of hardware and software components. • Hardware is the physical equipment such as the case, floppy disk drives, keyboard, monitor, cables, speakers, and printers. • The term software describes the programs that are used to operate the computer system. Computer software, also called programs, instructs the computer on how to operate. These operations may include identifying, accessing, and processing information.

  3. Computer Software • There are two types of software: operating systems and applications. • Application software accepts input from the user and then manipulates it to achieve a result, known as the output. Examples of applications include word processors, database programs, spreadsheets, web browsers, web development tools, and graphic design tools. • An Operating System (OS) is a program that manages all the other programs in a computer. It also provides the operating environment with the applications that are used to access resources on the computer.

  4. Operating Systems • Examples of Operating Systems • The Disk Operating System (DOS) • Windows 98 • Windows 2000 • Windows NT • Linux • Mac OS X • DEC VMS • IBM OS/400

  5. Computer Types • Mainframes - The mainframe model consists of centralized computers, usually housed in secure climate controlled computer rooms. End users interface with the computers via "dumb terminals." These dumb terminals are low cost devices that usually consist of a monitor, keyboard, and a communication port to talk to the mainframe.

  6. Mainframe Computers • There are several advantages of mainframes: • Scalability, the ability to add more users as the need arises • Centralized management • Centralized backup • Low cost desktop devices (dumb terminals) • High level of security

  7. Mainframe Computers • There are several disadvantages of mainframes: • Character based applications • Lack of vendor operating system standards and interoperability in multi-vendor environments • Expensive, with a high cost for set up, maintenance, and initial equipment • Potential single point of failure (non-fault tolerant configurations) • Timesharing systems, which means that there is a potential for a bottleneck

  8. Personal Computers • There are several advantages of PC computing: • Standardized hardware • Standardized, highly interoperable operating systems • GUI interface • Low cost devices (when compared to mainframes), low cost of entry • Distributed computing • User flexibility • High productivity applications

  9. Personal Computers • There are several disadvantages of PC computing: • Desktop computers cost, on average, five times as much as dumb terminals, according to some industry estimates • No centralized backup • No centralized management • Security risks can be greater (physical, data access, and virus security) • High management and maintenance costs, although they are generally cheaper to maintain than mainframes

  10. Birth of the Internet • 1960’s - The U.S. Department of Defense (DoD) recognized the need to establish communications links between major U.S. military installations. The primary motivation was to maintain communications if a nuclear war resulted in the mass destruction and breakdown of traditional communications channels. • 1970’s - When the Advanced Research Projects Agency Network (ARPANET) project began, no one anticipated that the network would grow to the extent that it did. Throughout the 1970s, more nodes or access points were added, both domestically and abroad.

  11. Birth of the Internet • 1980’s - The Domain Name System (DNS) was introduced in 1984, providing a way to map "friendly" host names to IP addresses. It was much more efficient and convenient than previous methods. • 1990’s - ARPANET evolved into the Internet, with the U.S. government getting involved in pushing the development of the so-called information superhighway. • Today, there are millions of sites that exist on the World Wide Web, with millions of host computers participating in this great linking.

  12. Birth of the Internet

  13. Starting and Restarting a Computer • Starting a computer is also referred to as booting the system. • A "cold boot" is performed when the PC is turned on using the power button. • Restarting a PC that has already been powered up is referred to as a "warm boot." This can be achieved by pressing the reset button on the front panel.

  14. Shutting Down a Computer • Three ways to shutdown a computer • To shutdown the computer, click on the Start button on the lower left corner of the Windows Taskbar and select Shut Down. • Pressing Ctrl+Alt+Delete, and click Shut Down from the menu that displays. • Pressing Alt+F4 at the desktop, and selecting Shut Down from the menu that displays. • Note: It is extremely important not to power off the computer with the power switch. Most operating systems like Macintosh and Windows have a specific method for turning the system off. 

  15. The Desktop • The main display screen in Windows is known as the desktop. • Some of the icons on the desktop, such as My Computer, Network Neighborhood (or My Network Places), Recycle Bin, and My Documents, are shortcuts to those directories

  16. The Desktop • Located at the bottom of the desktop is the taskbar. • The taskbar contains the Start button, quick launch buttons, system tray, and the clock. • The Start button, displays the Start menu. This menu allows access to virtually every program and function on the PC. • Quick launch buttons are shortcuts to applications.

  17. Windows Explorer (Windows 2000) • To create a shortcut (icon), right-click the program or file (in Windows Explorer) and select Create Shortcut. • Explorer can be accessed in Windows 2000 by choosing Start > Programs > Accessories > Windows Explorer, from the Windows desktop.

  18. Windows Explorer (Windows 9x) • To create a shortcut (icon), right-click the program or file (in Windows Explorer) and select Create Shortcut. • With Windows 9x (95, 98, and Millennium), choose Start > Programs > Windows Explorer from the menu that displays.

  19. Switching Between Windows • When more than one window is open, the user can switch between windows by pressing Alt +Tab. While holding down the Alt button, keep pressing Tab to find the desired window. • Document windows can also be selected by clicking the desired document on the desktop taskbar, which displays at the bottom of the screen.

  20. Viewing Basic System Information • To view information about the system, go to the Start menu and choose Programs > Accessories > System Tools > System Information. Here you can view information such as the type of operating system, the processor type, and the type and amount of Random-Access Memory (RAM) that is installed.

  21. Adjusting the Screen Display • To adjust the screen display, first minimize all windows that are open. • Right-click on empty space on the desktop and choose Properties to open the Display Properties window. • Alternatively, from the Start menu choose Settings > Control Panel > Display.

  22. Start Menu Options

  23. Start Menu Options • The Help feature provides tips and instructions on how to use Windows, along with an index and search function so information can be found easily.

  24. Start Menu Options • Find/Search  • In Windows 95, 98, and Windows NT, Find is used to locate files, folders, and network connections to other computers and peripherals. • In Windows 2000, Find has been renamed Search. • Programs  • The Programs menu lists all of the programs that are installed on the computer.

  25. Start Menu Options • Documents  • The Documents menu shows a list of the most recent documents that have been accessed or created. • Run  • The Run feature is another method of starting a program, instead of clicking the program's shortcut icon on the desktop or on the list of programs within the Programs directory.

  26. Application Software • There are several types of application software: • Word Processor - an application that creates, edits, stores, and prints documents. • Spreadsheet - numerical data is stored in cells that are arranged on a grid. • Database - a collection of data that is organized so that its contents can be easily accessed, managed, and updated. • Graphics applications - used to create or modify graphical images. • Presentation applications - permit the organizing, design, and delivery of presentations in the form of slide shows and reports. • Web browser - an application that is used to locate and display pages from the World Wide Web.

  27. Measurement-related Terminology • Bit – The smallest unit of data in a computer. A bit can take the value of either one or zero, and it is the binary format in which data is processed by computers.  • Byte – A byte is a unit of measure used to describe the size of a data file, the amount of space on a disk or other storage medium, or the amount of data being sent over a network. One byte consists of eight bits of data.  • Nibble – A nibble is half a byte or four bits. 

  28. Measurement-related Terminology • Kilobyte (KB) – A kilobyte is 1,024 (or approximately 1,000) bytes.  • Kilobit (Kb) – A kilobit is 1,024 (or approximately 1,000) bits. • Megabyte (MB) – A megabyte is 1,048,576 bytes (or approximately 1,000,000 bytes).  • Note that a capital B indicates bytes while a lower case b indicates bits.

  29. Measurement-related Terminology • The following terms are standard measurements of the amount of data transferred over a network connection. • Kilobits per second (Kbps) –Kbps is a data transfer rate of approximately 1,000 bits per second.  • Megabytes per second (MBps) –MBps is a data transfer rate of approximately 1,000,000 bytes per second.  • Megabits per second (Mbps) –Mbps is a data transfer rate of approximately 1,000,000 bits per second.

  30. Measurement-related Terminology • Hertz (Hz) – Is a unit of measurement of frequency. It is the rate of change in the state or cycle in a sound wave, alternating current, or other cyclical waveform. • Common measurement of the speed of a processing chip. • Megahertz (MHz) – One million cycles per second. common measurement of the speed of a processing chip.  • Gigahertz (GHz) – One billion (1,000,000,000) cycles per second.

  31. Boolean Logic Gates • Computers are built from various types of electronic circuits. These circuits depend on what are called AND, OR, NOT, and NOR logic "gates." • These gates are characterized by how they respond to input signals.

  32. Boolean Logic Gates • AND • The AND gate acts as follows: if either input is off, the output is off. • AND is like multiplication Truth Table

  33. Boolean Logic Gates • OR • An OR gate acts as follows: if either input is on, the output is on. • OR is like addition Truth Table

  34. Boolean Logic Gates • NOT • A NOT gate acts as follows: if the input is on, the output is off, and vice versa. • NOT is the opposite of the input Truth Table

  35. Boolean Logic Gates • NOR • The NOR gate is a combination of the OR and NOT gates and should not be presented as a primary gate. A NOR gate acts as follows: if either input is on, the output is off. Truth Table First perform the OR operation, then perform the NOT operation.

  36. Numbering Systems Decimal (base 10) uses 10 symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 Binary (base 2) uses 2 symbols 0, 1 Hexadecimal (base 16) uses 16 symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F

  37. Base 2 Base 16 Numbering Systems Base 10

  38. 0 13 1 14 2 15 3 16 4 17 5 18 6 19 7 20 8 21 9 22 10 23 11 24 12 25 Binary Binary Decimal Decimal Binary Counting 0 1101 1 1110 10 1111 11 10000 100 10001 101 10010 110 10011 111 10100 1000 10101 1001 10110 1010 10111 1011 11000 1100 11001

  39. Convert the decimal number 192 into a binary number. 192/2 = 96 with a remainder of 0 96/2 = 48 with a remainder of 0 48/2 = 24 with a remainder of 0 24/2 = 12 with a remainder of 0 12/2 = 6 with a remainder of 0 6/2 = 3 with a remainder of 0 3/2 = 1 with a remainder of 1 1/2 = 0 with a remainder of 1 Write down all the remainders, backwards, and you have the binary number 11000000. Decimal to Binary ConversionMethod 1

  40. Convert the decimal number 192 into a binary number. First find the largest number that is a power of 2 that you can subtract from the original number. Repeat the process until there is nothing left to subtract. 192-128 = 64 128’s used 1 64-64 = 0 64’s used 1 32’s used 0 16’s used 0 8’s used 0 4’s used 0 2’s used 0 1’s used 0 Write down the 0s & 1s from top to bottom, and you have the binary number 11000000. Decimal to Binary ConversionMethod 2

  41. Convert the decimal number 213 into a binary number. First find the largest number that is a power of 2 that you can subtract from the original number. Repeat the process until there is nothing left to subtract. 213-128 = 85 128’s used 1 85-64 = 21 64’s used 1 *(32 cannot be subtracted from 21) 32’s used 0 21-16 = 5 16’s used 1 *(8 cannot be subtracted from 5) 8’s used 0 5-4 = 1 4’s used 1 *(2 cannot be subtracted from 1) 2’s used 0 1-1 = 0 1’s used 1 Write down the 0s & 1s from top to bottom, and you have the binary number 11010101. Decimal to Binary ConversionMethod 2

  42. 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 1 1 0 1 1 0 1 0 1 Binary to Decimal ConversionMethod 1 From right to left, write the values of the powers of 2 above each binary number. Then add up the values where a 1 exist. 128 + 32 + 16 + 4 + 1 = 181

  43. 128 64 32 16 8 4 2 1 1 1 0 1 Binary place value Binary number Conversion Binary to Decimal ConversionMethod 2 • Start from the left with the first 1 in the binary number. Write down a 1 below it. • Then look at the next number to the right • if it is a 0, double the previous number and write it down • if it is a 1, double the previous number and add 1 to it, then write it down • Continue this until you reach the last 0 or 1 in the binary number. • The last number you write down is the decimal equivalent of the binary number. 1 3 6 13

  44. Base 16 Hexadecimal to Decimal Conversion • Each number place represents a power of 16 • Given the hexadecimal number 12A • 1 X 256 = 256 • 2 X 16 = 32 • A X 1 = +10 (A = 10 in hex) • 298

  45. Hexadecimal to Binary Conversion To convert a hex number to a binary number, each hex bit represents 4 binary digits Given the hex number A 3 A is the decimal number 10 10 in binary is 1 0 1 0 8 4 2 1(binary number places - 4 bits) 1 0 1 0 3 is the decimal number 3 3 in binary is 0 0 1 1 8 4 2 1(binary number places - 4 bits) 0 0 1 1 hex A 3 = 1 0 1 0 0 0 1 1 in binary

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