Epson EQUITY 386SX/16 PLUS - Manual (Page 205)

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 Reference Manual. 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 C-17