When you load MS-DOS from the hard disk, the operating system is copied to the computer’s memory; however, all the MS-DOS programs remain only on drive C and are not copied to memory. When you turn off the hard disk, the computer no longer has a drive C. This means that if you type a command such as DISKCOPY, the operating system will not be able to find it because there is no drive C.

This may not matter if you are using an application program (such as a word processing or spreadsheet program) because once it is loaded, you will use the commands provided by the program. However, if you want to store data on the hard disk, you need to turn it back on.

Note

Some application programs have overlays which must be on the current drive. For these types of programs, you need to run them from drive A.

The following example shows the proper procedure for turning the hard disk off while the computer is on.

1.Suppose you turn on the computer with the hard disk switch on. MS-DOS loads from the hard disk.

2.Next type A: and press Enter to log on to drive A.

3.If you want to load an application program from the hard disk, do it now. Be sure to type C: and the pathname of any subdirectories, as necessary, in front of the name of the application program.

You must to do this before you turn off the hard disk. You may also want to copy any files you will be using from drive C to drive A.

Note

If you are still logged on to drive C when you turn off the hard disk, the next time you enter a command, the screen displays an error message. If this happens, turn the hard disk back on and then log on drive A.

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