Commodore PC - Page 342

270 MS-DOS User's Reference
Usually, you will want to recover by typing responses in this ^m0*^
order:
R (to try again) W
A (to terminate a program and try a new disk)
U
One other error message might be related to faulty disk reading
or writing:
File Allocation Table bad for drive v v—'
x
This message means that the copy in memory of one of the alloca-
tion tables points to nonexistent blocks. Possibly the disk was
incorrectly formatted or not formatted before use. If this error
persists after you format it, the disk is unusable.
u