Epson 10020 - Manual (Page 67)

You can enter an MS-DOS command whenever you see the
MS-DOS command prompt. Type the command name and any
necessary parameters and delimiters and then press Enter to
execute the command. MS-DOS does not execute your
command until you press Enter.
You can type command names and parameters in either
uppercase or lowercase letters. If you make a mistake when
typing a command and you notice it before you press Enter,
you can do either of two things:
Use the backspace key to back up to the error so you can
correct it
Press ESC to cancel the command line.
If you press Enter when a command line has an error in it, the
screen displays an error message. Usually, the command prompt
reappears so you can try again. Type the correct command and
press Enter.
Creating and Managing Files
All your data and programs are stored in files on disk. A data
file contains information, such as words, numbers, or pictures.
A program file contains instructions that the computer can
understand and execute.
The kind of file you create depends on the MS-DOS command
or application program you use to create it. In general, a data
file that you create using an application program is stored in a
special format. If you use a different application program to
read that file, you may encounter problems.
When you create a file, you need to give it a name. You must
name your files in a certain format required by MS-DOS.
3-8 Using MS-DOS With Your Computer