Epson Equity 320SX PLUS - Manual (Page 177)

Caution
The hard disk format procedure destroys any data on your
hard disk.
You may want to reformat a hard disk if you have a serious
problem with the drive. However, before formatting a disk
with data on it, try every other recovery procedure described
in your MS-DOS manuals. Then back up all the data on the
disk before you begin.
Note
If you do not enter a bad track list before you format the
disk, the format program analyzes the surface of the hard
disk to determine the bad tracks.
Media Analysis
This test identifies the bad tracks on the hard disk by
analyzing the surface of the disk to find them. The program
uses three different bit patterns; formatting the disk, marking
the bad tracks, and displaying the bad track list.
Caution
The Media analysis test destroys any data on your hard
disk.
Performing System Diagnostics B-17