IBM System/7 Functional Characteristics - All about the IBM 1130 ...

Operator ControlsThe following operator controls are located on the front of the disk storage module.FILE WRITE SwitchThe setting of this switch determines if data can be written on the disk in the module. Whenthe switch is in the normal position, both reading and writing can be performed. Whenthe switch is in the write inhibit position, only read commands are accepted by the diskstorage module.IPL SwitchThis switch is operable only on models 1 and 2 of the disk storage module. It selects theupper or lower disk in the module that will be used in an initial program load (IPL) operationfor the System/7.DRIVE SwitchThis switch turns power on or off to the disk drive in the module if system power is on.The drive must be turned off in order to change disk cartridges.FILE READY IndicatorThis indicator turns on when the disk file can be used by the System/7 program. It remainson until the disk file is turned off or a file not ready condition occurs. A file notready condition is caused by errors detected in the disk storage module. For details ofthese error conditions, see "Error and Status Conditions" in this chapter.Data SecurityData stored on the 5022 Disk Storage Module can be given additional security by use ofthe file write switch located on the front of the module. Data on the disk(s) cannot bechanged by a program if the file write switch is set to prevent writing on the file, asdescribed previously under "Operator Controls."IBM 5022 Disk Storage Module 15-3