Commodore 1541-II - Page 47

closed file (splat file), indicated by an asterisk (*) next to its file type in the directory, that
diskette needs to be validated. In fact, but for the one exception below, it is a good idea to
validate diskettes whenever you are the least bit concerned about their integrity.
The exception is diskettes containing Direct Access files, as described in Chapter 7.
Most direct access (random) files do not allocate their sectors in a way the Validate
command can recognize. Thus, using Validate on such a diskette may result in un-
allocating all direct access files, with loss of all their contents when other files are added.
Unless specifically instructed otherwise, never use Validate on a diskette containing direct
access files. (Note: these are not the same as the relative files described in Chapter 6.
Validate may be used on relative files without difficulty.)
FORMAT FOR THE VALIDATE COMMAND
PRINT#15,"VALIDATE*)"
or abbreviated as
PRINT#15,"V0"
where "0" is the drive number (always 0 on the 1541.) As usual, it is assumed file 15 has
been opened to the command channel on the 1541.
EXAMPLE:
PRINT#15,"V0'
VALIDATING THE DISKETTE: BASIC 3.5
The Collect command in Basic 3.5 is the same as the Validate command in Basic 2.
It recalculates the Block Availability Map (BAM) of the current diskette, allocating only
those sectors still being used by valid, properly-closed files and programs. All other
sectors (blocks) are left unallocated and free for re-use, and all improperly-closed files are
automatically Scratched. However, this bare description of its workings doesn't indicate
either the power or the danger of the Collect command. Its power is in restoring to good
health many diskettes whose directories or block availability maps have become muddled.
Any time the blocks used by the files on a diskette plus the blocks shown as free don't add
up to the 664 available on a fresh diskette, Collect is needed (with one exception below.)
Similarly, any time a diskette contains an improperly-closed file (splat file), indicated by
an asterisk (*) next to its file type in the directory, that diskette needs to be collected. In
fact, but for the one exception below, it is a good idea to collect diskettes whenever you
are the least bit concerned about their integrity. Just note the number of blocks free in the
diskette's directory before and after using Collect, and if the totals differ, there was indeed
a problem, and the diskette should probably be copied onto a fresh diskette file by file,
using the Copy command described in the previous section, rather than using a backup
command or program..
The exception is diskettes containing Direct Access files, as described in Chapter 7.
Most direct access (random) files do not allocate their sectors in a way Collect can
recognize. Thus, collecting such a diskette may result in un-allocating all direct access
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