The Disk Operating System

The Disk Operation System (DOS) has been around since the early 1980′s.   This was before GUI’s (IE Apple Macintosh 1984).  It is an example of an operating system that has a command line interface.  There are no icons to click and in fact no mouse to use.  The DOS environment is similar to the command line Unix/Linux interface.   We will use DOS as a stepping stone to Linux, an operating system that is heavily used in industry and universities.   Once you become familiar with  DOS, switching to Unix/Linux will be very easy.

All operating systems, whether they are command line or GUI or both, are responsible for managing the resources of a computer system.  (Resources include things like disk drives, Jump drives, memory , files, monitors, processors etc) .  It is in control of these so consequently the user is required to ask the OS to access/modify the resource for him/her.  You may ask the system to delete a file or print a file or run a program.  In a CMI (command line interface) you type a command and hit return.  The OS then executes the command.  The main thing to pay attention to is the format of the command.  You must know it syntax (how it is typed) and its semantics (the meaning of the command, IE what is supposed to occur).

Lets now start up DOS and get started.  It is YOUR responsibility to practice the following procedures until you become proficient in the given DOS commands. You should be able to start up the DOS window by clicking START, then run and then typing in cmd. This works with Windows XP. If you are using Windows Vista then your must click START, click all programs, click Accessories and then click run and type cmd. The GUI for XP and Windows 7 are different. I know, this is a pain, but we must do what we must do. In Windows 7 the START has been replaced with a windows circle icon,Lower left corner, just click that and type cmd.

You can right click on the top bar of the DOS window that appears in order to modify its properties such as the window size, font size, etc.  Try it.   Just right click on the bar and select properties at the bottom.

In general you should be able to move around the DOS directory trees using the following commands.

  1. [dir] List the directory that you are presently at. Know the meaning of the data presented on each line of the directory
  2. D: Just typing the drive letter will move you to that drive.
  3. [cd ..] move to the parent of the directory that you are presently viewing
  4. [cd name] After you dir the directory you can change to the directory name using this command.
  5. [cd \] This will move you to the top of the directory tree. This is called the root directory.
  6. [notepad] This will execute the notepad editor, allowing your to create and save files. This is not the same editor as notepad++. You cannot execute notepad++ from the command line!
  7. [del filename] This will delete a file named filename. Do a dir command to make sure the file is there before you delete it.
  8. [type filename] This will list, ie type out, the contents of the file your have just saved with notepad. If you want to work in the DOS window while your notepad editor is still open you first need to click once in the DOS window. You can then work in that window. If you desire to go back to the notepad window just click there once you you are back in notepad. Note that this is not notepad++. Notepad++ is a much better version of notepad.
  9. [Attrib  filename]  Display or modify the access rights etc of a file.
  10. Know the difference between an absolute path name and a relative path name. ( See Sibels discussion above)

Practice the above, moving around in DOS, creating and saving file in notepad (notepad++ later on) and then finding these files in DOS and typing them. Also review the meaning of a text file and the ASCII (American Standard Code for Information Interchange) code table.

Here are the usual names for referring to size of Files, Memory or devices etc.

8 bits = 1 Byte

1024 Bytes = 1 Kilobyte (KB)

1,048,576 Bytes = 1 Megabyte (MB)

1,043,741,824 Bytes = 1 Gigabyte (GB)

1,099,511,627,776 Bytes = 1 Terabyte (TB

If you have problems with any of the above see myself or my assistant. We will continue on monday with this type of thing looking closer at the files we create using notepad. We will also look at binary and hex number formats.

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