Abstract: A progressive addition power lens having base and add spherical regions for providing refractive power correction for distance and near vision includes a central corridor characterized by a power curve expressed as a polynomial of at least the 11th degree. The surface contour of the intermediate corridor is defined by the surfaces of an ordered sequence of osculating spheres. The curvature of the surface of the intermediate region spreads away from the principal meridian in accordance with a spreading function having substantially circular level curves. Visual astigmatism is corrected over a substantial fraction of the base and add spheres by superposition of an aspheric function to the sag of the lens surface as defined by the polynomial and the spreading function.

Abstract: A mechanism for communicating messages, each including a command and a response, in a network having central processing complexes (CPCs) and one or more coupling facilities. Each coupling facility has a central processor for executing instructions and a main storage. Messages are sent from a message control block in the main storage of the CPC sending the message, and the response to the message is received in a message response block of the CPC without an interrupt to the program being executed by the central processor of the CPC. Each message from a CPC to the coupling facility may include a command and an indicator bit which instructs the coupling facility to execute the command either in synchronism with or asynchronously to the execution of the sending processor. The coupling facility executes the command and returns a response which is received in a message response block of the main storage of the sending CPC without an interrupt to any program being executed by the central processor of that CPC.

Abstract: A method for controlling coherence of data elements sharable among a plurality of independently-operating CPCs (central processing complexes) in a multi-system complex (called a parallel sysplex) which contains sysplex DASDds (direct access storage devices) and a high-speed SES (shared electronic storage) facility. Sysplex shared data elements are stored in the sysplex DASD under a unique sysplex data element name, which is used for sysplex coherence control. Any CPC may copy any sysplex data element into a local cache buffers (LCB) in the CPC's main storage, where it has an associated sysplex validity bit. The copying CPC executes a sysplex coherence registration command which requests a SES processor to verify that the data element name already exists in the SES cache, and to store the name of the data element in a SES cache entry if found in the SES cache. Importantly, the registration command communicates to SES the CPC location of the validity bit for the LCB containing that data element copy.

Abstract: A message path mechanism in a network having central processing complexes (CPCs) joined by message paths to a coupling facility. The coupling facility locates message paths for sending messages from one CPC to another and for sending messages between the coupling facility and one or more of the CPCs. A message path status table is provided having an entry for each of the message paths. Each entry has an indicator indicating whether its message path is active or inactive. multiple connections between the coupling facility and systems in the CPCs are registered in the coupling facility. Also provided is a mechanism for validating that each message path is connected properly such that if a message path is disconnected and then reconnected to a CPC, the validation mechanism insures that the message path has been reconnected correctly.

Abstract: In a multi-system complex having central processing complexes (CPCs) and subsystems, a hardware facility for prompt interdicting I/O and message operations. A CPC or subsystem failure causes as interruption in the availability of the data bases to the attached network of terminals. Often such networks have thousands of terminals. Even a short loss of data is detrimental. Therefore the CPC or subsystem takeover must be accomplished as quickly as possible and the I/O attached to the failing CPC or subsystem must be interdicting to release it for use to the rest of the complex. The disclosed hardware facility provides a mechanism which is program initiated and controlled and which guarantees the prompt completion of the interdiction function.

Abstract: A shared coupling facility contains system lock management (SLM) means for supporting a distributed locking protocol used by a plurality of sharing lock managers each executing on a processor having access to the shared memory and to any other processors in the processor complex. A request to lock a resource shared among the lock managers is first checked against a local hash table and then, if necessary, forwarded to the system lock management means in the shared memory for synchronous or asynchronous processing. List structures are maintained in the shared coupling facility to support the protocol, and are used by the system lock management means to record data recovery status. The sharing lock managers interact with the SLM means to control/manage lock contention, waiter queueing, and compatibility processing.

Abstract: A Structured External Storage (SES) device/processor is connected to two or more DP systems, thereby loosely coupling the systems. The SES is capable of holding data objects of two distinct types (List objects and Cache objects), and communicates commands and command responses with the systems using a message protocol. A support facility within a processor on which a system is executing receives status indications from the SES without interrupting mainline system execution. Within the SES, a serialization mechanism allows more than one command to execute in parallel without loss of data object integrity, or command consistency. A forward completion mechanism sends to systems early notification of completion of certain commands, without permitting results inconsistent with this notification to be obtained by the systems. And a restart mechanism permits interrupted commands to be restarted by the initiating system or, in certain cases, by another system.