Epson 486SX - Manual (Page 83)

Reassigning the Diskette Drives
If your system has two diskette drives, they are connected
inside your computer so that the top drive is A and the bottom
drive is B. Because drive A is
the
boot drive, whenever you want
to load the operating system or a bootable program from a
diskette, you must insert the diskette into drive A.
If both of your drives are the same 1.44MB
capacity, for example-you never need to reassign the drives. If
your two drives are different types, however, you may need to
change the drive letter assignments so you can boot the
computer from drive B. For example, you may have a
program disk which you need to use to boot the computer. Or
you may have an application program that requires you to
leave the key disk in drive A while you run the
program.
For these situations, you can reverse the drive assignments to
make the top drive B and the bottom drive A. There are two
ways to do this:
Insert the diskette in drive B and turn
on
the computer.
The drive automatically becomes drive A.
Run the AFDD program to reassign the drive. See “Using
the AFDD Program,” below, for instructions.
Your assignments remain in effect until you press the
RESET
button or turn off the computer, or until you reassign the drives
to their original assignments. The reassignment remains in
effect if you reset the computer from your hard disk by
entering the command.
Enhancing System Operations 4 - 7