Epson Y16499100301 - Manual (Page 124)

The pattern looks like this:
The text data includes all the characters commonly used by
programs that require foreign languages or graphic characters. If
your printer prints different characters than you see in the
illustration, you may need to take care with certain software.
The dot graphics data is sent to the printer using a command
(ESC K) compatible with Epson and IBM printers. If this
pattern is printed correctly, you can use the MS-DOS
GRAPHICS program to print our copies of graphics screens.
Note
Even if the test runs only for a short time, your printer may
store many characters in its buffer. To stop printing, set the
printer off-line.
Hard Disk Drive and Controller Check
Use this option to test the performance of the hard disk
drive installed in your computer. If any errors occur, have your
dealer check and service the drive. When you select option 17
from the DEVICE LIST, you see this menu:
HARD DISK DRIVE AND CONTROLLER CHECK MENU
1 - Seek check
2 - Write,
read check
3 - Error detection and correction check
4 - Read, verify check
5 - Run all above checks
0 - Exit
Enter selection number:
D-20
Performing System Diagnostics