Atari DOS 2.5: XF551 Owner's Manual page 55

Unlike the same function of the eartier DOS 2.0S, DUPLICATE
DISK in DOS 2.5 will format your destination diskette. However,
keep in mind that you cannot duplicate an enhanced density
diskette using an ATARI810 Disk Drive as your destination drive.
If your computer system includes both an XF551 and an 810 Disk
Drive, or if you have and use files originally created and stored
using DOS 2.0S, see Appendix H for detailed information on
managing your files and diskettes with DOS 2.5. See Appendix L
if you want to use files formatted with DOS 3.
The duplication process is a sector·by·sector copying technique.
This means that not only are all your files copied from the source
to the destination diskette , but they are also located in the same
sector number on both diskettes. The directory of the source
diskette is also copied onto the destination diskette. For this
reason , any files previously stored on the destination diskette will
have been destroyed when the duplication process is complete.
So if you use an old diskette for the destination diskette , be sure
that none of the files on it are valuable.
You should always save BASIC or assembly language programs
that are currently in RAM before attempting to duplicate a disk·
ette. There is no internal buffer for DUPLICATE DISK as there is
for the COPY FILE command, and MEM.SAV (if in use) will be
invalidated if you give DOS permission to proceed (and to use
the program area). The DUPLICATE DISK option always uses
the program area (where a RAM-resident BASIC program is
stored) as a buffer for moving the files on the source diskette to
the destination diskette.
Duplication Using a Single Disk Drive
In a single disk drive system, the source and destination drives
are both Drive 1 (see example).
Always write-protect your source diskette as a safety measure .
Then ,
if it
is accidentally inserted in place of the destination disk-
ette , the screen will display an ERROR·144, and your source
diskette will still be intact.
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