Commodore PC 20 - Page 187

If you type Y, diskcomp prompts you to insert the proper disks
and does the next comparison. If you type N, diskcomp ends. If
the disk in the default drive does not contain MS-DOS and -you end
diskcomp, you'll receive the followiJ:~g message:
Insert disk with COMMAND.COM in drive A
and strike any key when ready
Diskcomp does not work on network drives, and you cannot use
it with assigned, joined, or substituted drives. If you attempt to
use the diskcomp command with these types of drives, it displays
an error message.
Note When comparing a disk with a backup disk that you made
with the copy command, you may receive the "Compare error"
message, even if the files on the disks are identical. This is
because
the copy command duplicates the information, but
doesn't necessarily place it in the same location on the target disk.
In this case, you should use the
FC utility to compare individual
files
on the disk. See Chapter 8, "File Comparison Utility (FC)."
MS-DOS Commands 491
When correctly written programs exit back to MS-DOS, they return Diskcomp exit codes
an exit code: 0 if no error occurred, or a value greater than zero
if there was a problem. This exit code can be tested in batch files,
and it allows batch programmers
to "branch" to an error-handling
routine in the batch file.
The
diskcomp command returns the following exit codes:
o Compared OK
The disks compared exactly.
1 Did not compare
The disks
were not the same.
2
CONTROL-C error
The user terminated with CONTROL-C.
3 Hard error
An unrecoverable read or write error occurred - did
not compare.
4 Initialization error
There is not enough memory - invalid drives or com-
mand line syntax.
You can use the batch processing if command to perform error
processing based on the en-orlevel returned by diskcomp_