Abstract: A peripheral subsystem accepts and responds to a plurality of supervisory channel commands which alter the operation of the subsystem; i.e., logically partition, break the logical partition, adjust or amend the logical partition, ignore the logical partition, give operator controls for loading and unloading a record cartridge, suspending multipath reconnection and the like. These supervisory commands can be located anywhere in a I/O chaining sequence. Some of the supervisory commands will result in changes in the subsystem operation for the duration of the instant channel program or CCW chain while others persist for as long as the subsystem is operating or until a subsequent supervisory command overrides the previous supervisory command. One of the supervisory commands can selectively inhibit subsequent supervisory commands only within a given I/O chain. This selective inhibit provides subsystem integrity. At the end of the chain, the inhibition is removed.

Abstract: A peripheral device subsystem enables its peripheral devices to operate asynchronously with respect to attaches hosts through the use of managed buffers, new multiple data transfer modes, control and error recovery operations. In a preferred first or buffer mode of operation, all data of each record being transferred can be resident in a buffer before transfer to either a host or device. For a host to device write transfer, receipt of such a record by the buffer results in the subsystem signaling to the host a completion of a transfer to an addressed device even though the device has received none or only part of the data. In a second or tape write mode, recording data in a peripheral device, such as a tape recorder, completion of recording is not signaled until after the buffer has transferred the data to the recorder.

Abstract: In a storage subsystem employing removable record media such as contained in a cartridge, each storage recorder has a multidigit alphanumeric display located immediately above a cartridge receiver. The symbols on the display are arranged to be aligned with the symbols on the cartridge when inserted into recorder so that visual correlation is facilitated. Each recorder has a microprocessor which controls the display in response to host supplied LOAD DISPLAY commands. Each command includes a cartridge identification field for displaying on the display for such verification as well as orders for setting up display modes and display sequencing. The recorder microprocessor will display status of the recorder in response to a control field of the LOAD DISPLAY message at predetermined drive states, display a cartridge number after a cartridge has been removed from the recorder (i.e., the number of the cartridge to be inserted), inhibit a recorder status message or error message until the recorder is READY, i.e.

Abstract: A peripheral device subsystem enables its peripheral devices to operate asynchronously with respect to attaches hosts through the use of managed buffers, new multiple data transfer modes, control and error recovery operations. In a preferred first or buffer mode of operation, all data of each record being transferred can be resident in a buffer before transfer to either a host or device. For a host to device write transfer, receipt of such a record by the buffer results in the subsystem signaling to the host a completion of a transfer to an addressed device even though the device has received none or only part of the data. In a second or tape write mode, recording data in a peripheral device, such as a tape recorder, completion of recording is not signaled until after the buffer has transferred the data to the recorder.

Abstract: A data-processing system is connected to a peripheral system by a plurality of channel paths. These channel paths are named as members of path groups. Each path group has one or more channel paths. Within each path group, communications between the data-processing system and the peripheral system are multipathed among the paths in such path groups. Devices within the peripheral system are selectively assignable to access groups for exclusive use within one or more of such path groups; a given path group selectively provides communication paths for each device in an access group. Each access group includes one or more path groups. Temporary suspension and reassignment facilities are disclosed. Both devices and channel paths can be either in a grouped or ungrouped state. The assignment function to access groups is particularly useful in interleaved channel transfers for ensuring subsystem integrity.

Abstract: A peripheral subsystem, such as a tape storage subsystem, assigns logical and physical values to blocks of signals received from a host. A host can retrieve such values for use later to locate the blocks of signals and for error recovery purposes. In a buffered peripheral subsystem, such values define current signal transfer status of the buffer.