Abstract: Enables an I/O channel program to use IDAWs (indirect data address words) to control data transfers from/to an I/O (input/output) device to/from either or both of ES (expanded storage) and/or system MS (main storage), in which data moved to/from ES does not move through MS. ES and MS are plural electronic storage media in a data processing system, and the I/O device is any I/O device selectable by the system. Intermixing of data transfers between ES and MS may be controlled by a single IDAW list accessed by a channel control word (CCW) in a channel program in a data transfer direction indicated in the CCW without any channel mode change.

Abstract: Provides a dynamic execution link between an analyzer program and each hook instruction in a program. Special types of hook instructions are provided for use in a hooked program. The link causes the analyzer program to execute as part of a continuous uninterrupted execution for each hook instruction. The link uses hardware and/or internal code to access a hook control area which provides linkage information needed to invoke the execution of the analyzer program upon completion of the hook instruction and to continue the execution of the hooked program following the completion of the analyzer program. The linkage information includes the entry location into the analyzer program, and also locates the first hook work area (HWA) of a sequence of HWAs, from which an HWA is assigned to each current hook instruction. The assigned HWA stores a return point location in the hooked program at an instruction following the current hook instruction.

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: A method and apparatus for translating a large logical address as a large virtual address (LVA) when a dynamic address translation (DAT) mode is on. Each LVA is separated into three concatenated parts: 1. a highest-order part (ADEN) for indexing into an access directory (AD) to locate an entry (ADE) for locating one access list (AL); 2. an intermediate part (ALEN) for indexing into a selected AL to access an entry (ALE) that enables location of an associated conventional address translation table which represents a conventional size virtual address space; and 3. a low-order DAT virtual address (VA) part having the same size as a conventional type of virtual address. The low-order DAT VA part is translated by the associated conventional address translation table. If a carry signal is generated during the creation of the low-order DAT VA part, then a change in the selection of an ALE results.

Abstract: An improved DLAT structure distinguishes between address spaces and data spaces. The DLAT structure classifies data spaces by one or more space identifications which control assignment of virtual page addresses to DLAT rows. In one embodiment, a "private space bit" is used to select different DLAT addressing algorithms. In another embodiment, data spaces are sub-classified using space identification bits, and for each sub-class, a unique algorithm is selected based on the page address bits. An Exclusive OR function is used to generate the DLAT selection bits. This approach minimizes private space synonyms while maximizing common space synonyms. The result is improved performance since the former minimizes thrashing and the latter maximizes the value of the DLAT common bit.

Abstract: A single non-privileged instruction copies a page of data from a source virtual address in an electronic medium to a destination virtual address in the same or in a different electronic storage medium, and without the intervention of any supervisory program when each medium and the virtual addresses are previously determined. The instruction is not required to specify which medium it will use, does not require its user to know what backing medium it will access, does not require main storage (MS) to be its backing medium, and allows different types of physical addressing to be used by different media. The instruction can lock any page for use in a multi-processor (MP). No physical direction of data movement is provided within the non-privileged machine instruction, which only designates virtual direction of movement. The separation of virtual direction from physical direction is done by avoiding instruction control over selection of electronic media.

Abstract: A computer system has general purpose registers, control registers and access registers for containing information to allow address space capability. A linkage stack uses protected address space to store state information during program call and program return operations. The linkage stack contains information relating to state entries for the saved information and header and trailer entries to point to other linkage stack sections. A control register contains the pointer to the current linkage stack entry and is changed as the program call or return moves through the stack.

Abstract: A non-main storage data space (NMDS) is presented, whose virtual pages may be backed by expanded storage, by a combination of expanded and auxiliary storage, but not by main storage. Mechanisms are provided to prevent direct referencing of data in a NMDS by instructions, and to bring data into and out of NMDS's. The I/O mechanisms minimize physical I/O by exchanging pointers to backing pages in appropriate cases. Additionally, control is returned immediately to I/O-initiating applications, when I/O is required between an address space and a NMDS, without the need for synchronization by the application: the mechanism provides for synchronization by the system's page fault processing.

Abstract: A linear data set is mapped to one or more non-main storage virtual data spaces. Portions of this data space are then selectively mapped to a "window" in an address space in which an application is executing, and changes made in this "window" are temporarily saved in the data space. After completion of processing, the application may permanently save changed data from the data space to the linear data set.The technique for mapping the data space to the address space may be used to map between two address spaces, and may be extended to encompass third and subsequent spaces, so that a reference to a mapped address in the first space will ultimately be interpreted as a reference to an address in the last mapped space.

Abstract: A program authorization mechanism for authorizing access to an address space in the main memory of a computer system by a program being run under a multiple address space facility. An access-list entry is associated with each address space, each access-list entry being designated by an access-list-entry token contained in an access register. Each access-list entry includes a private indicator which indicates if the associated address space can be accessed by all programs from this access-list entry or if the associated address space can only be accessed by an authorized program. For program to be authorized, an extended authorization index in a control register must match an access-list extended authorization index in the access-list entry, or the extended authorization index value must be authorized in an authority table associated with the address space. An instruction for testing a given extended authorization index for a given access-list-entry is also disclosed.

Abstract: Within a data processing system, a control mechanism for supporting a data space without common segments in addition to traditional address spaces containing common segments. Logic for eliminating duplication of lookaside table entries for virtual addresses within shared segments, but not for identical virtual addresses within data address spaces is provided, as well as for overriding low address protection for store operations into data spaces. Thus, the entire virtual addressing range is available to programs wishing to use such data spaces for data isolation and data sharing.

Abstract: A method and apparatus is provided to translate the contents of access registers into information for use in performing addressing functions for multiple virtual address spaces. The access registers represent the full addressing capability of the system but do not directly contain the addressing information. The system has a plurality of general purpose registers, a plurality of access registers associated with the general registers, an access list having access list entries which is addressed by the contents of the access register, memory storage for holding address space number second table entries (ASTE), where the contents of the access list entry locate the ASTE and where the ASTE contains the addressing information needed to translate a virtual address when combined with the contents of a general purpose register. Access register translation (ART) consists of the process of determining addressing information by using the access list entry and the ASTE.

Abstract: The disclosure provides a general purpose register (GR) mask which associates predesignated address spaces with respective GRs assigned to contain a base value for calculating logical addresses within the address spaces. An address space mask register has a plurality of digit positions which receive the respective digit values comprising a particular GR mask. A respective digit position is selected by a base GR address signal provided by a storage address request from a CPU instruction decoder. The particular value of the selected digit in the mask register controls the selection among a plurality of STO registers, which designate a plurality of simultaneously available address spaces. The selected base GR is used in a System/370 B, D or X, B, D type of logical storage address representation. A base GR explicitly contains an intra-address-space base value.

Abstract: The embodiment provides an independent data bus path between a random access page storage (PS), and a main storage (MS), wherein this independent data bus does not pass through any channel processor (CH) or central processor (CP). Page data transfers on the independent data bus can be controlled either (1) asynchronously by a channel processor (independently of any central processor instruction stream), or (2) synchronously by a CP (independently of any CH operation). Novel CP instructions enable the CP to synchronously control the transfer of pages in either direction on the independent data bus.A channel program for controlling the page transfer may be initiated by a start I/O (SIO) or start subchannel (SSCH) instruction in the CPU, and it accesses a special field in a channel address word (CAW) that designates the use of the page storage. Novel PS channel command words (CCWs) in the channel program enable CH to control page transfers on the independent data bus.

Abstract: The detailed embodiment associates access registers (AR's) with the general purpose registers (GPR's) in a data processor. The AR's are each loaded with a unique STD (segment table descriptor). The STD comprises a segment table address in main storage and a segment table length field. There are 15 AR's associated respectively with 15 GPR's in a processor to define a subset of up to 15 data address spaces. The STD in an AR is selected for address translation when the associated GPR is selected as a storage operand base register, such as being the GPR selected by the B-field in an IBM System/370 instruction. The invention allows each AR to specify that it does not use the STD in its associated AR to define its data address space, but instead uses the STD in the program address space AR.