so, the ACF indexes down the magazine until it finds the first cell with a cartridge in the import position. The ACF sets the cell-status indicator LED for that cell to in-use (steady green) and moves the cartridge from the cell to the device.

2.If the ACF is disabled and in Automatic mode and a cartridge is placed in the import position of the priority cell, the ACF is enabled. It then loads the cartridge in the device, and sets the cell-status indicator LED to in-use (steady green) for the priority cell.

3.If a cartridge is placed in the priority cell while the ACF is enabled and in Automatic mode, the ACF sets the cell-status to in-use. The in-use indicator LED of the priority cell is (steady green). When the ACF completes its current operation, it automatically loads the priority cell as described in step 2.

4.When a cartridge that was loaded while in Automatic mode is unloaded, it is returned to its original cell, if possible. The in-use indicator LED for that cell is then turned off. The ACF then searches the magazine for the next cell in the import position and loads it in the device. This process repeats until the ACF cannot find another cartridge to load.

System Mode

System mode provides the operator an additional mechanism to keep the drive continually loaded with cartridges from the magazine. When the ACF is enabled, and the first cartridge loaded, subsequent load commands are under the control of the attaching host. The ACF loads one cartridge in response to each of these system commands until all the cartridges in the magazine are processed.

System mode does not preclude specific mount requests from the attaching host. The operator can supply specific cartridges to an application by inserting the cartridge in the priority cell. The priority cell cartridge is automatically the next cartridge to be loaded in the device, provided a load operation is not currently in progress. When the specific cartridge is complete, the ACF automatically resumes processing cartridges from the magazine under system control.

Processed cartridges can be removed from the magazine, and unprocessed cartridges can be added, without disturbing the ACF. The ACF locates each unprocessed cartridge.

When the ACF is in System mode, the following applies (see also “ACF Notes” on page 56):

vInitial conditions

– System mode must be selected from the SET ACF MODE menu.

Chapter 4. Automatic Cartridge Facility (ACF) and Magazine 61

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IBM 3590 manual System Mode