Epson CW3S16 Operation Manual page 191

Figure E-10. Performing the Hard Disk Read/Verify Test
Check Test Cylinder Test
The last cylinder on the hard disk is the test cylinder. This
cylinder should be tested if a C:Drive or D:Drive error occurs
during the POST. A Read/Verify test is performed on all
sectors in the test cylinder. This test should pass in at least one
sector. If the test fails in all sectors, then one of two possible
problems has occurred. Either the test cylinder itself is faulty, or
too many cylinders were specified for the hard drive in the
CMOS Setup program.
To perform the Check Test Cylinder Test:
E-28 Advanced ROM Diagnostics