Commodore Plus 4 - Page 346

334 Using Peripheral Devices
Validating a Diskette
Whenever a file is added to a diskette, the DOS updates the directory and the
BAM. Occasionally the two do not match, when, for example, a file was opened
but never closed. The COLLECT or validate command must be used to remedy
this situation. Never SCRATCH an unclosed file. (Unclosed files are denoted
with an asterisk in the directory listing.) Do not COLLECT a diskette that has
had sectors written to it with the direct-access commands described in the next
section. The COLLECT command syntax is
COLLECT Ddrive, ON Uunit
; where drive is the optional drive number (which is not needed for the 1541) and
unit is the disk drive's device number. If omitted, the unit is assumed to be 8.
To collect a diskette by direct command to the DOS, use
PRINT# filenumber,"V"
where filenumber is the logical file number of the previously opened command
channel.
Deleting Files on a Diskette
To delete a properly closed file from the diskette, the SCRATCH command is
used. Its syntax is
SCRATCH filename,'Ddrive,'Uviiit
where filename is the name of the file to be deleted, drive is the optional drive
number (which is not needed on the 1541), and unit is the disk drive's device
number, which is assumed to be 8 if not specified. Do not SCRATCH an
unclosed file. Instead, use the COLLECT command described previously. Wild
cards may be used in the file name for a SCRATCH to delete every file with a
matching file name, but caution is advised because one can easily delete large
numbers of files by using them.
To delete a file by direct command to the DOS, use
PRI1TT# filenumber,"S:filename"
where filenumber is the logical file number of the previously opened command
channel and filename is the name of the file to be deleted.
Note: If you inadvertently SCRATCH a valuable file, you may be able to
recover it. For more information, see the direct-access programming section.