Ibm 3480 Magnetic Tape Subsystem Operating Mode - IBM 3480 User Reference

The tape drives can be assigned to specific channels by program action.
This assignment ability replaces the mechanical switching used for channel
assignment for earlier tape drives. For more information on channel
assignment, see IBM 3480 Magnetic Tape Subsystem Planning and
Migration Guide.
IBM 3480 Magnetic Tape Subsystem Operating Mode
In MVS systems, the 3480 subsystem can operate as a 3480 in full function
mode, or it can operate in 3420 compatibility mode. System generation
controls the mode in which the 3480 operates. Both the 3480 in full
function mode and the 3480 in 3420 compatibility mode cannot both be
generated at the same time on the same system. If you are generating
a 3480 in full function mode, you cannot generate compatibility mode for
any other 3480s on the system. However, catalog entries for both the 3480
and the 3420C are synonymous, and both entries can exist in the same
catalog. This allows you to share catalogs among systems or migrate to a
full function 3480 without changing catalog entries. Each system uses the
catalog entry appropriate to the 3480 device type that was generated on
that system. VM and VSE/SP support for the 3480 is comparable to that
provided in MVS compatibility mode.
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When the 3480 is operating in compatibility mode, the following 3480
features are supported:
• Tape write-immediate mode (OPT CD
=
W)
• Full error recovery (ERP) support
• Buffered read and write mode
• Hardware-initiated message display.
When the 3480 is operating in compatibility mode, the following 3480
features are not supported:
• High-speed search (block locate)
• Program-initiated message display (MSGDISP macro)
• Dynamic device reconfiguration (DDR)
• Processor assignment
• User-requested synchronization
• Automatic cartridge loader in System mode.
For more information on the functions of the 3480 in full function or
compatibility mode, see IBM 3480 Magnetic Tape Subsystem Introduction
and IBM 3480 Magnetic Tape Subsystem Planning and Migration Guide.
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IBM
3480
Magnetic Tape Subsystem User's Reference