Controlling asynchronously operating peripherals

In a method of operating a peripheral subsystem having a plurality of addressable peripheral devices and a programmed control unit commonly connected to the peripheral devices;

• the steps of:
• grouping some of the peripheral devices into redundant device groups;
• making one of the peripheral devices in each of the groups a primary device and all the rest of the peripheral devices in each group secondary devices;
• removing the capability of all secondary devices from being addressable by addresses received by the subsystem from outside the subsystem and within the subsystem making all of the secondary devices addressable through the primary device in the same group;
• retentively storing identification and status information of all said groups and peripheral devices assigned to each said group;
• receiving into the subsystem a command for a primary device requesting the address of said secondary devices within the group;
• and
• for all of the secondary devices within the group, sending an untagged interrupt to outside the system with the respective address of the secondary devices for indicating that the secondary devices are in the group with the primary device receiving said command.

For use in a programmable host processor having addressable storage locations for storing program indicia and control data indicia and means for addressing the addressable storage locations and for controlling asynchronous operations of a connected peripheral subsystem, a set of program indicia having program steps and associated control data structures, including in combination;

• vector table indicia containing first and second host processor addresses for first and second control data indicia and being located at a given one of the addressable storage locations;
• configuration table indicia at the first address and containing a third address in a plurality of control data entries respectively for a plurality of peripheral subsystems with a first entry being for a first peripheral subsystem having a first subsystem identification (SSID) and being located at a given address offset within the configuration table indicia;
• a plurality of subsystems control block indicia located at the third address with subsystem control block indicia for the first peripheral subsystem and containing a fourth address pointer;
• a plurality of device table indicia with one device table for each device attached to a host processor within the first peripheral subsystem and having fifth and sixth address pointers, the device table indicia being located at said fourth address;
• a plurality of unit control blocks (UCB), one for each device attached to the host processor and each UCB having the second address and entry offset for the peripheral subsystem in which the respective device exists;
• each of the control blocks being located at said fifth address for a respective one of the device table indicia, said sixth addresses having a same range of addressability for the UCB's as said fifth addresses, predetermined ones of the device tables having a fifth and sixth address with the fifth and sixth address in each of the respective device tables pointing to a different UCB and others of the device tables only having a fifth address;
• IOS program indicia for communicating with a subsystem and being coupled to said vector table indicia and having program indicia for receiving SSID signals with interruption signals from a subsystem, and said coupling to the vector table indicia including means for passing the SSID signals thereto;
• and
• AOM program indicia coupled to the IOS program indicia and to all of the control data indicia and having indicia for accessing the vector table indicia for reading the SSID signals, then for selecting a subsystem control block based on the SSID signals and accessing a device table indicia for accessing a fifth and sixth address for identifying a group of UCB's addressable by both fifth and sixth addresses whereby a group of devices in the subsystem can be identified.