Epson EQUITY 386/33 PLUS - Manual (Page 90)

Choosing the Correct Drive Buy
Your computer has two horizontal drive bays and one vertical
mounting position which hold up to three drives, as shown
below.
vertical
mounting
horizontal drive bays
Your computer may have come with a hard disk drive already
installed in the vertical mounting position. If not, you can
install one 3½-inch hard disk drive in this position.
If you are installing your first hard disk drive, it is best to install
it in the vertical mounting position. If you add a second hard
disk drive or diskette drive, use the lower horizontal drive bay.
5-2 Installing and Removing Drives