Commodore 1541 - Save and Replace

SAVE
To SAVE a program to the diskette, all that is needed is to add the device number
after the program name. Just like the SAVE command for the tape deck, the device
number can be followed by a command number, to prevent the automatic re-location
on LOADing (sec the section on the LOAD command, above).
FORMAT FOR THE SAVE COMMAND:
SAVE namel, device*, command//
See the LOAD command (page 10) for an explanation of the parameters device^
and command^.
When you tell the disk drive 10 SAVE a program, the DOS must take several
steps. First, it looks at the directory to see if a program with thai name already exists.
Next it checks to see that there is a directory entry available for the name. Then it
checks [he BAM to see if there are enough blocks in which to store the program. If
everything is OK up to this point, the program is stored. If not, the error light wilJ
flash.
SAVE AND REPLACE
If a program already exists on the disk, it is often necessary to make a change and
re-SAVE it onto the disk. In this case, it would be inconvenient to have 10 erase the old
version of the program and then SAVE it.
If the first characters of the program name are the M@" sign followed by a 0 and
a colon (:), the DOS knows to replace any old program that has thai name with the
program that is now in the computer's memory, The drive checks the directory to find
the old program, then it marks thai entry as deleted, and it next creates a new entry
with the same name. Finally, the program is stored normally.
FORMAT FOR SAVE WITH REPLACE:
SAVE "@0:" + nameS, device*, command*
For example, if a file was called TEST, the SAVE and replace command would be
SAVE "@0: TEST'\8. If the name is in AS, the command is SAVE AS + "@0:
TEST", 8.
The reason for the 0: is to keep compatibility with other Commodore disk
drive units which have more than one drive built in. In that case, the number 0
or 1 is used to specify which drive is being used.