Epson Apex 20020 - Manual (Page 68)

Chapter 1 describes how to use DISKCOPY to copy your
MS-DOS and Reference diskettes. To make backups of other
diskettes, use the DISKCOPY command or the MENU
program. See Chapter 4 for more instructions on using
DISKCOPY and MENU.
It is best to put most of the programs and data files you use
regularly on the hard disk. Keep backup copies of all your
program files on diskettes, however, and regularly copy
important data files to diskettes as well. For more information,
see “Backing Up Data” in Chapter 4 and check your MS-DOS
Reference Manual.
Using a Single Diskette Drive
The operating system expects the computer to have at least
two diskette drives, and it displays prompts and messages
accordingly. If the computer has only one diskette drive,
MS-DOS treats the one drive like two logical drives. This helps
you perform operations that normally require two diskette
drives.
Usually, MS-DOS recognizes the first diskette drive (the top
drive) as drive A and the second diskette drive as drive B. If
you have only one diskette drive, MS-DOS recognizes it as
both A and B.
For example, if you give a command to copy from A to B,
MS-DOS copies data from the diskette you place in the single
drive (A) to the computer’s memory. Then MS-DOS
automatically prompts you to insert another diskette in the
same drive, which it now identifies as drive B. It copies the
data from memory to the new diskette. When the copying is
complete, MS-DOS identifies the drive as drive A again, and
you see a prompt to insert the original diskette into drive A.
You can load the operating system and application programs
from the hard disk, create and store your data there, and use
the diskette drive just for copying data to and from diskettes.