Epson 10020 - Manual (Page 190)

Write, Read Check
This check tests the ability of the hard disk drive to read and
write data. The test writes to and reads from each sector of the
innermost cylinder of the disk, using each head.
Note
This test destroys all data on the innermost cylinder of the
selected hard disk drive. This cylinder is reserved for
diagnostics, and is never used for storage by MS-DOS.
Therefore, data created by MS-DOS is not destroyed.
Select option 2 from the menu to start this test. You see these
messages:
The data on the highest physical cylinder
may be destroyed by this check.
Enter Y to start this check.
Enter N to return to the menu.
Press Y and then Enter to continue with the test. You do not
see a cylinder count during the test. If no errors occur, the
program returns to the menu.
If an error is reported, make a note of the code and message.
Then use the Non-destructive surface analysis (option 4 on the
HARD DISK FORMAT MENU) to check the condition of the
hard disk. If this analysis shows no other problems with the
disk, follow these steps:
1. Rack up all the files on your hard disk with the BACKUP
command, described in your MS-DOS Reference Manual.
2. Re-format the disk using option 2, Format hard disk, on the
OPERATION MENU. See Appendix E for instructions.
3. Prepare the hard disk for use with FDISK and SELECT. See
Appendix F for instructions.
Performing System Diagnostics D-33