Epson Apex 20020 - Manual (Page 163)

Hard Disk Controller and Hard Disk Check
The computer next checks the hard disk controller and drive
unit. If a malfunction is found in the hard disk controller card,
you see this error number and message:
1782-Disk controller failure
If an error is found in the hard disk drive unit, the screen
displays one of these error messages:
178n-Disk n error
179n-Disk n error
where
n
is 0 or 1, and represents the drive number of the hard
disk. Drive C is number 0, and drive D is number 1.
Power-On Diagnostics B-5