Restoring MS-DOS System Files
The MS-DOS files COMMAND.COM, IO.SYS, and MSDOS.SYS are necessary for the
operation of your computer. If any of these files are accidentally deleted or modified, your
computer will not function. This appendix describes the procedure for restoring these
files without affecting the applications and data files that may be on your hard disk.
Note: IO.SYS and MSDOS.SYS are hidden files. You will not see these files if you view
a directory of drive C using the DIR command.

If COMMAND.COM is Missing

If COMMAND.COM is missing from your hard disk, the screen displays this message
during the boot process:
Bad or missing Command Interpreter
The computer then becomes inactive. Complete the steps in the next section to restore
COMMAND.COM to your hard disk.

If IO.SYS or MSDOS.SYS is Missing

If the IO.SYS and/or the MS-DOS.SYS files are missing from your hard disk, the screen
displays the following message during the boot process:
Non-System disk or disk error Replace and press any key when ready
This message is repeated when any key is pressed. Complete the following steps to restore
IO.SYS or MSDOS.SYS to your hard disk.
1. Turn off the computer and insert the 3.5-inch MS-DOS 4.01 SHELL
floppy into the floppy drive.
2. Turn on the computer and when the computer prompts you for date and
time, press the Enter key.
E-10 Troubleshooting