Abstract: A method and system for controlling references to system storage. Milli-code mode provides a flexible technique for overriding storage controls associated with referencing system storage of a data processing system. The storage controls to be overridden are not replaced and therefore, a restore of the previous contents of those controls is not necessary. This allows for an increase in system performance and an increase in the efficiency and flexibility of the system. In addition to the above, a system request instruction is provided, which enables flexibility in the manner in which system requests are executed. The flexibility of the system request instruction reduces the number of instructions needed to perform system requests.

Abstract: Asynchronously transfers blocks of data (called pages) between two different electronic media of a data processing system. The different media may be a system main storage and a system expanded storage or a non-volatile external type of storage, either of which use different addressing than the main storage. All of these storages may be made of DRAM or SRAM technology with battery backup when necessary. The invention splits the involvement of a program requesting a page transfer into a pair of instructions per page transfer executing on one or more central processors. The first instruction of a pair starts another processor that controls the asynchronous page transfer, and the second instruction of the pair enables the communication of the end of the page transfer to the program. Neither instruction in the pair interrupts the program for the page transfer. A processor executing the starting instruction is immediately free to execute any other available instructions.

Abstract: An improved error recovery system in which all operations which the Central Processor performs are categorized into one of a plurality of recovery types. The determination of category is made based on which architected and machine dependent facilities they manipulate and the manner in which the facilities are manipulated. This classification of instructions into types allows for the amount of checkpoint data to be minimized while allowing recovery to be generalized into broad algorithms instead of handling each operation independently. Furthermore, by applying this classification technique to various phases of execution (recovery windows) of instructions which modify system facilities before they complete, these instructions can also be retried with a minimum of hardware and algorithms.

Abstract: A CPU interface recognizing a large very number of I/O interruption queues in a logically partitioned data processing system. Different partitions may contain different guest operating systems. The CPU interface controls how plural CPUs respond to I/O interruptions put on numerous hardware-controlled queues. A host hypervisor program dispatches the guest operating systems. The guests use the I/O interruptions in controlling the dispatching of their programs on the CPUs in a system. The invention allows the number of guest partitions in the system to exceed the number of I/O interruption subclasses (ISCs) architected in the system, and enables the dispatching controls of each guest operating system to be sensitive to different priorities for plural programs operating under a respective guest. The invention provides CPU controls that support alerting the host to enabled I/O interruptions, and provides CPU controlled pass-through for enabling direct guest handling of the guests I/O interruptions.

Abstract: The embodiment discloses a method and means for partitioning the resources in a data processing system into a plurality of logical partitions. Host control code may be embodied in programming, microcode, or by special hardware to enable highly efficient operation of a plurality of preferred guest programming systems in the different partitions of the system. The main storage, expanded storage, the channel, and subchannel resources of a system are assigned to the different logical partitions in the system to enable a plurality of preferred guest programming systems to run simultaneously in the different partitions. This invention automatically relocates the absolute addresses of the I/O channel and subchannel resources in the system to their assigned partitions. Also the absolute and virtual addresses of the different guest programming systems are relocated into, as well as page addresses for any expanded storage, their assigned partitions.