mme gefils
MME GEFILS switches primary and secondary logical units for a file code. If no secondary unit has been assigned, the peripheral device assigned to the primary logical unit is used.
After a call to MME GEFILS, the A and Q registers will be zero if the file was released or is a system file. Otherwise, the Q register contains the following:
Bits 0-5 Zero 5-11 Device Address 12-13 IOM/IOX/IMU/IOP number 14-15 Reserved for GCOS 16-23 Eight-bit channel address 24-35 Reserved for GCOSand the A register contains the following:
Bits 0-5 Device Code 6-8 Disposition Code: 000 Released 001 Dismount 010 Save 011 Continue 9-19 Reserved for GCOS 20-23 High density default from .CROPT 24-27 Low density default from .CROPT 28-31 Density from bits 0-3 from PAT word 3 32 Mode indicator for 1600-bpi tapes 33-34 Density history bits 35 Reserved for GCOSThe meaning of tape density values is given in "expl mme gefadd".
When files must be switched, the user program usually must issue mounting/dismounting instructions to the operator; however, with the File and Record Control function, the mounting/dismounting instructions are issued automatically.
The process of purging files is affected by MME GEFILS. If a file has alternate reels which are switched through MME GEFILS (or through a File and Record Control call to FORCE), the reels will not be purged. A multi-reel file using a single tape drive will only have the current reel purged.
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