Epson Equity 286 PLUS - Manual (Page 213)

Check Test Cylinder
This test checks the test cylinder, which is the last cylinder on
the hard disk. You should perform this test if you receive a hard
disk error when you boot the system.
Force Bad Tracks
Use this test to mark bad tracks on the hard disk without
formatting it.
Caution
The Force bad tracks test destroys any data on your hard disk.
Hard Disk Error Messages
The diagnostics program displays two types of error messages
while testing the hard disk: messages the program generates and
those the controller generates.
The following message appears if you try to run the Performance
Test with less than 128KB of available memory:
Insufficient memory for data transfer
Minimum memory required is - 128KB
performing System Diagnostics C-29