Commodore 1541 - Appendix F: VIC-1541 vs. 1541 Drives; General Differences Overview; Reference Designator Mapping; Theory of Operation Differences

CLOSE
it is extremely important that you properly CLOSE files once you are finished
using them. Closing the file causes the DOS to properly allocate blocks in the BAM
and to finish the entry in the directory. If you don't CLOSE ihe file, all your data will
be lost!
FORMAT FOR CLOSE STATEMENT:
CLOSE file*
You should also be careful not to CLOSE ihe error channel (channel* 15) before
CLOSEing your data channels. The error channel should be OPENed first and
CLOSEd last of all your files! That will keep your programs out of trouble.
If you close the error channel while other files are OPEN, the disk drive will
CLOSE them for you, but BASIC will still think they are open (unless you CLOSE
them properly), and let you to try to write to them.
NOTE: If your BASIC program leads you into an error condition, all Tiles are
CLOSEd in BASIC, without CLOSEing them on your disk drive! This is a very
dangerous condition. You should immediately type the statement OPEN 15, 8, 15,
"I". This will re-initialize your drive and make all your files safe,
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