COBOL Manual for TNS and TNS/R Programs

Tape Input and Output
HP COBOL Manual for TNS and TNS/R Programs—522555-006
27-25
Mount Messages
Topics:
•
Unlabeled Tapes
•
Labeled Tapes
Unlabeled Tapes
Without labels, the operating environment cannot use automatic volume recognition to
locate the tape, so the mount message from the HP COBOL run-time routine specifies
the tape drive on which to mount the tape—the tape drive specified by the DEVICE
attribute of the file’s DEFINE.
If the mount message appears on a terminal display, you can specify a different tape
drive on which to mount the tape. Respond to the mount message by typing the device
name of the new tape drive after the colon:
TYPE RETURN OR $DEVICE (OR 'NO' TO END INPUT): $TAPE
HP COBOL opens the tape drive you specify.
If a DEFINE exists for the tape file and you specify a different device in response to an
HP COBOL mount message, the HP COBOL run-time library alters the DEVICE
attribute of the file’s DEFINE.
If no DEFINE exists for the tape file, the HP COBOL run-time library creates a DEFINE
with the required attributes (including the DEVICE attribute).
The new DEVICE attribute value or the new DEFINE remains active until one of these
occurs:
•
The HP COBOL process terminates.
•
The HP COBOL process uses a DEFINE procedure to change the value of the
DEVICE attribute or to delete the DEFINE.
•
The HP COBOL run-time library changes the value of the DEVICE attribute when
you specify a different device for the file in response to another HP COBOL mount
message.
Labeled Tapes
A mount message from the labeled-tape processing software usually does not specify
a device on which to mount the tape. The labeled-tape processing software uses
automatic volume recognition to find a tape volume on one of the system’s tape drives,
so you or the operator can mount the tape on any available tape drive. For a
continuation reel of a multitape file, however, a mount message from the labeled-tape
processing software specifies the same device as the first reel.