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AM-64x DAT High Capacity Tape Drives
PDI-00649-00, A01
DAT Drive Compatibility
By default, AM-648 and AM-649 DAT drives write data in compressed mode. This compressed data
cannot be read by the AM-647 DAT drive. However, by using the TMODE command with standard
DDS/DDS-1 tapes, you can force the AM-648 and AM-649 drives to write in standard DDS (non-
compressed) mode. Data written in standard DDS mode can be read by AM-647, AM-648 and AM-649
drives.
The AM-649-01 (8GB) DAT uses higher density 120mm DDS-2 tape cartridges to achieve its
larger storage capacity. The drive defaults to DDS-2-DC high compression mode whenever a
DDS-2 tape is used, or to the DDS-DC compression mode whenever a DDS-1 tape is used. This
is the only DAT drive currently offered by Alpha Micro that supports the DDS-2 tape format.
Additionally, you cannot write in DDS or DDS-DC format on a DDS-2 tape. However, by using
a DDS-1 tape with the TMODE command (as explained below) you can force the drive to
operate in DDS non-compressed mode. Tapes created in non-compressed DDS mode can be
interchanged between other Alpha Micro 4mm DAT drives.
The TMODE command allows you to switch between compressed and non-compressed write modes.
The program will display the currently set data format and the available write options when you enter the
TMODE command with the device name. For example:
TMODE DAT0:
RETURN
Recording format: DDS-DC (compression)
Options for this drive:
DDS - standard 2GB format
DDS-DC - compressed 4GB format
DDS-2 - standard DDS-2 format
DDS-2-DC - compressed DDS-2 format
Older versions of the 647DVR.DVR will neither display nor support the DDS-2 options! Also, if
you select a DDS-2 option you must have a DDS-2 tape installed, or the selection will be
disregarded.
To force an AM-648 or AM-649 drive to write in standard DDS (non-compressed) mode, enter this
command at the AMOS prompt:
TMODE DAT0: DDS
RETURN
To set DDS-DC compressed data mode, enter this command:
TMODE DAT0: DDS-DC
RETURN
In addition to tapes written in standard DDS mode, the AM-648 and AM-649 DAT drives can
interchange tapes created in DDS-DC compression mode. However, the AM-649-01 (8GB) drive
will only operate in DDS-2 or DDS-2-DC mode when DDS-2 tapes are used.
