c64 guru: save a file again

From: Cameron Kaiser <spectre_at_floodgap.com>
Date: Tue Mar 9 21:24:37 2004

> It seems I can't save a file twice with the same name
>
> ... write basic program ...
> save "program",8
> ... edit basic program ...
> save "program",8
> (light on floppy blinks - error )

This is a "feature" of Commodore DOS (the error is 63, FILE EXISTS, 00, 00).
You can handle this in two ways.

1. Save-with-replace:

SAVE"_at_0:PROGRAM",8

This has a notorious bug on 1541 disk drives that tends to strike when
the disk is very near capacity, since both copies of the program must
exist on the disk at once. A safer approach is to

2. Scratch first, save later.

OPEN15,8,15,"S0:PROGRAM":CLOSE15
SAVE"PROGRAM",8

This is the safest approach as it has the least chance to go berserk unseen.

Many disk wedges like Epyx FastLoad and DOS WEDGE 5.1 reduce the OPEN
statement to _at_S0:PROGRAM or >S0:PROGRAM or some such variant. Alternatively,
have a block in your program like this:

63998 END
63999 OPEN15,8,15,"S0:PROGRAM":CLOSE15:SAVE"PROGRAM",8

then RUN 63999 whenever you want to save-and-replace.

-- 
---------------------------------- personal: http://www.armory.com/~spectre/ --
 Cameron Kaiser, Floodgap Systems Ltd * So. Calif., USA * ckaiser_at_floodgap.com
-- Backup not found. Abort, Retry, Vomit, Panic, Write Resume File? -----------
Received on Tue Mar 09 2004 - 21:24:37 GMT

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