Commodore 1541-II - Erasing Programs

If the disk copy of the program differs even a tiny bit from the copy in memory,
"VERIFY ERROR" will be displayed, to tell you that the copies differ. This in itself
doesn't mean either copy is bad, but if they were supposed to be identical, one or the other
has a problem.
Naturally, there's no point in trying to verify a disk copy of a program after the
original is no longer in memory. With nothing to compare to, an apparent error will
always be announced, even though the disk copy is always and automatically verified as it
is written to the disk.
FORMAT FOR THE VERIFY COMMAND:
VERIFY "drive #:pattern",device #, relocate flag
where "drive #:" is an optional drive number (0 on the 1541,) "pattern" is any string
expression that evaluates to a file name, with or without pattern-matching characters, and
"device #" is the disk device number, normally 8. If the relocate flag is present and
equals 1, the file will be verified where originally saved, rather than relocated into the
Basic text area.
A useful alternate form of the command is:
VERIFY "*",device#
It verifies the last file used without having to type its name or drive number. However, it
won't work properly after save-with-replace, because the last file used was the one
deleted, and the drive will try to compare the deleted file to the program in memory. No
harm will result, but "VERIFY ERROR" will always be announced. To use verify after
@SAVE, include at least part of the file name that is to be verified in the pattern.
One other note about Verify—when you Verify a relocated file, an error will nearly
always be announced, due to changes in the link pointers of Basic programs made during
relocation. It is best to only verify files saved from the same type of machine, and
identical memory size. For example, a Basic program saved from a VIC 20 can't easily be
verified using a Commodore 64, even when the program would work fine on both
machines (unless the program is re-saved). This shouldn't matter, as the only time you'll
be verifying files on machines other than the one which wrote them is when you are
comparing two disk files to see if they are the same. This is done by loading one and
verifying against the other, and as suggested, can only be done on the same machine and
memory size as the one on which the files were first created.
ERASING OLD PROGRAMS: BASIC 2
The Scratch command allows you to erase unwanted files, and free the space they
occupied for use by other files. It can be used to erase either a single file, or several files at
once via pattern-matching.
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