Computer Fundamentals

  1. Hardware Fundamentals
    1. Input Devices (keyboard), Output Devices (monitor) and the CPU

      2.  A model expression for computer operation is the following:
      INPUT - PROCESS - OUTPUT This means that information is delivered (input) to the computer, the computer processes the information and then sends (outputs) processed information to the user.
      Thus, a computer is composed of hardware that performs these three functions, input, process, output.

      The most common imput devices are the keyboard and the mouse although many other input devices exist. For example, a computer may monitor a hospital patient's heartbeart via contacts placed on the patients chest. The contacts are an input device.

      The most common output devices are the monitor and printer. These enable the computer to present information in a format that humans can understand.

      The CPU (Central Processing Unit) has primary responsibility for processing data. All the complex processing that a computer performs, no matter how sophisticated, can be done with three simple functions (instructions). These are 1) add two numbers, 2) move a number from one location to another and 3) compare two numbers and act upon the result of the comparison.

      For example we might instruct the computer to do the following.

      IF X < Y THEN A = A + 1 ELSE B = B + 1

      This instructs the computer to increase the number A by one if X is less than Y, otherwise increase the number B by one.
      Of course far more complex circuitry is normally built into most modern computers for speed and convenience reasons. However, the three simple instructions listed above are all a computer needs to function.

    2. Primary Memory/RAM
      In order for a computer to store and move information it needs some place to put it. Information that is currently being accessed (used) by the CPU is stored in Primary Memory, also called Main Memory or RAM.
      For example, if we are using a word processing program to write a letter then the letter is stored in Primary Memory. In fact the word processing program itself is stored in Primary Memory as well.

      Primary Memory is necessary because the CPU can not access data directly from disk. The data must first be copied from disk to Primary Memory to make it accessible to the CPU.

      Primary Memory is volatile. This means that if power is cut-off to the computer the information in Primary Memory is lost. That is why it is important to save our work to disk frequently when using a computer application such as a word processor or a spreadsheet.

    3. Disks and Disk Drives

      4. Since Primary Memory is volatile we need a device on which we can permanently store information. That device is called a Disk. A Disk is very similar in many respects to a CD except that whereas we cannot record onto an ordinary CD, information can be written to or read from disks. Like a CD a disk needs a device on which to "play" it. This device for computer disks is called a disk drive. Computer disks come in many sizes, speeds and price ranges and hold from one million to hundreds of billions of "bytes" of information. A byte is equivalent to one character where a character may be a digit, a letter or some other special character such as !, @ #, $, etc.

      1. Hard Drives

        2. "Hard" Disk Drives are mounted (semi-)permanently in the system box (the enclosure that holds the computer's internals). They consist of many "platters" and may hold from one billion to several hundred billion bytes of information.

      2. Diskettes

        3. Diskettes (sometimes called floppy disks) normally may hold only about 1.4 million bytes. Diskettes are removeable so they may be transported from one computer to another. They are a very common means of moving data from one computer to another. Their low capacity, however, limits their usefulness for this purpose.

      3. Network Drives
        Computers may have access to disk drives that reside on other computers if the computers are connected via a network. A network is simply a "wired" connection between computers. The connection does not even have to be permanent. For example, people may use their phone line to temporarity connect to the grandest netowrk of them all, the Internet. Also, with today's wireless technologies, "wired" can refer to a connection made via microwave or satellite.

        At Lynchburg College students have their own private directories on a special server computer whose name is erin. Since erin is always active and connected to the Internet students can access information they have placed on erin from almost anywhere in the world at any time of day or night.

      4. Other - CDs, ZIP, etc.

        5. As technology has advanced many other types of disk drives have and will continue to appear. The ZIP drive is similar to a diskette in appearance and functionality yet holds more than 100 times as much data. The newest CDs can be written to with a special CD drive and hold over 500 million bytes of data. It is likely these will become standard equipment because of the CD's universal acceptance as a media.

    4. Other Secondary Storage Devices
      There is still a place in today's computing world for non-disk mass storage devices. The tape drive has been with us from almost the beginning of computing time and still retains a useful, if diminished, role in many computer operations. Tapes and similar devices will continue to have a role as long as there is a need for large amounts of inexpensive storage.

    5. Interface Boards, Power Supplies, etc.

      6. It is beyond the scope of this course to delve into much detail on many of the other components that inhabit the system box of modern computers. However, we would be remiss if we did not mention the power supply. Internally, computers must use, relatively, low-voltage DC (Direct Current) power. Usually 5 - 12 volts DC is what is required. The electric receptacles that populate the walls of our offices and homes, however, dispense 115 volt AC (Alternating Current) power. A computer power supply accepts the 115 volt AC household current and converts it into 5 - 12 volt DC current for the computer's internal components.

      There are many devices that do not come as standard equipment on most equipment. One that may soon become standard is the network card. The network card consists of computer circuits placed onto a circuit board. The purpose of the network card is to enable a computer to communicate with other computers on a network. Circuit boards like this plug into special slots that are mounted on the computer's "mother board" or "system board". The system board is the basic platform upon which all the major internal electronic components are mounted. Special cards/boards like network cards are plugged into slots on the system board so that other components like the CPU or Primary Memory may have access to them.

  2. What is an Operating System?

    3. Computers function with "bits" of information in the form of electrons or magnetic charges or pulses of light. They do think or communicate in the same manner that humans do. The Operating System is a computer program that acts as an intermediary between the computer's internal components and the human who wishes to operate the computer. Basically, an Operating System makes the components of a computer accessible to the user. Operating systems such as Windows or Unix may also present a "user interface" to the persons operating the computer. The user interface is, basically, what we see on the monitor outside of a particular application such as a word processor or a spreadsheet program.

    I have given, above, a rather crude yet, hopefully, functional definition of an operating system. The reader should be aware that the term probably cannot be accurately defined. In fact the dispute between the U. S. Department of Justice and Microsoft Corp. is, in part, over what actually constitutes an operating system.

    Probably the most important function of the operating system is the management of files. Files are, arguably, the most important concept a competent computer user needs to master. All information and all programs on a computer are stored in files. We will discuss files more fully later in this module.

  3. Windows and Unix

    4. The two most prevalent operating systems are Microsoft Windows and Unix. In the earlier days of computers every computer had its own operating system. It soon became clear that this was not practical or desirable. Windows runs on almost all models of PCs and on DEC Alpha computers. Unix runs on dozens of different computers including PCs. In fact, Unix was designed, in part, to be portable. In saying Unix is portable we mean that Unix will run on most computers.

    As with all operating systems Windows and Unix have their strong points and weak points. For each there is an environment for which it is most suitable. We will not settle the operating system controversy (i.e., which is better) in this course but you should know that such a controversy exists.

  4. Booting the system, handling diskettes, etc.

    1. The Boot or Bootstrap Process
      The process of starting or restarting a computer by loading and executing (running) its operating system is called "booting" the computer. The process of starting a computer is not like starting most other "household appliances". There is a dilemma . Ordinary computer programs like text editors are loaded from disk into primary memory by the operating system at the user's request. Recall that the operating is also a computer program. So how can the operating system itself be loaded from disk if there is no active operating system to load it. This is a classic chicken and egg situation (i.e., which must come first?). The answer is that a special program is embedded in the computer hardware. This program resides in a non-volatile ROM (Read Only Memory) chip called the "boot ROM". Since the boot ROM is non-volatile it retains its contents when power is removed from the computer.

      The computer is constructed (hard-wired) so that when the computer is restarted by turning on the power switch the program on the boot ROM chip automatically runs. The sole purpose of the program on the boot ROM is to load the operating system into primary memory and cause it to begin running. The program on the boot ROM chip is called the bootstrap program. The process of restarting the computer is called booting or bootstrapping the computer because the computer is compared to the person who pulls him/herself up by his/her own bootstraps (an old saying that younger generations may not be familiar with.)

    2. When should I reboot/restart the computer?

    3. Handling Diskettes

    4. Backups are IMPORTANT!

    5. Computer Viruses

  5. Introduction to the Command Language

    6. Although both Windows and Unix (through XWindows) are able to present a "graphical user interface" to the user both also have a more fundamental mode of operation. MS-DOS, the core of the Windows operating system, has a special set of english-like commands called the DOS command language. Unix has a similar set of commands. Since we have better access to PCs than to Unix computers here on campus we will focus on MS-DOS's command language rather than Unix's.

    To access the MS-DOS command language one must either "boot" (restart) the computer in MS-DOS mode or run MS-DOS in "shell" mode (i.e., as if it were an application running under Windows). Once in MS-DOS mode we will see a system prompt. The system prompt lets us know that DOS is ready to accept commands. Once in DOS mode we no longer have the Windows graphical user interface so the mouse becomes non-functional unless we run a DOS program that allows us to use the mouse. We will discuss in detail many of the DOS commands during the course. I will only give a few here.

      A Few DOS Commands
    • CHKDSK - Check a disk for errors.
    • DATE - Display the date and, optionally, allow the user to set the computer's calendar.
    • FORMAT - Format a disk to make it ready to accept data.
      (NOTES: FORMAT destroys all data on a disk. A disk only needs to be formatted once.)
    • TIME - Display the time and, optionally, allow the user to set the computer's clock.
    • VER - Display the current version of DOS in use on this computer.

  6. Files and File Management Commands

    1. ASCII vs. Binary Files

    2. Programs and other specialized files.

    3. File Management Commands
        A Few DOS File Management Commands
      • CD - Change directory. I.e., move to another directory.
      • COPY - Make a copy of a file and, optionally, give the copy a new name.
      • DEL - Deletes (removes) a file.
      • DIR - Display a list of the names of files in the current directory.
      • MD - Make a new directory.
      • PRINT - Send a file to the printer.
        (NOTE: Only works for ordinary ASCII files or special printer files.)
      • REN - Change the name of a file.
      • RMDIR - Remove a directory.
      • TYPE - Display the contents of a file on the monitor.
        (NOTE: Only works for ordinary ASCII files.)

  7. Network Commands and Programs You Should be Able to Use
    • IPConfig/all
    • WinIPCfg/all
    • Net Config
    • Net Time
    • NetStat (Note that this is all one word - no space)
    • Ping (host name or IP address)
    • Telnet (host name or IP address)
    • TraceRt (host name or IP address)

  8. Directories and Subdirectories/Folders


  9. Using a Text Editor (Word Pad)
    1. Launching Word Pad

    2. Locating a File in a Directory

    3. Opening a File

    4. Different File Types

    5. Using the Editor to Create Text

    6. Saving a File
      The most universal format for saving a file is ASCII text. This is sometimes called DOS text. ASCII stands for American Standard Code for Information Interchange. Homework files created in this class will be either standard ASCII text files or HTML files (web pages). We will not be using word processing files such as Microsoft WORD or Wordperfect in this class.



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