Epson 20 - Manual (Page 172)

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 occurs, 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. Back up all the files on your hard disk.
2. Re-format the disk using option 2, Format hard disk, on the
OPERATION MENU.
3. Recreate the MS-DOS partition with FDISK and format it with
SELECT (See Chapter 3.)
4. Restore your files.
Read, Verify Check
This test reads and verifies data from all tracks of the disk, checking
each cylinder and using all read/write heads.
Select option 3 from the menu to start this test. The program displays
the number of each cylinder it finds. For example, with a hard disk,
the first message you see is:
Current cylinder is nnn
C-28 Performing
System Diagnostics