Abstract: A first bank or a second bank of storage locations of a control store of a data processing system is enabled in response to one of a plurality of test signals received as parallel inputs by two multiplexer devices. Only one of the multiplexers is enabled at a given time in response to the polarity of one of the test signals selected from the inputs of the multiplexer devices.

Abstract: One or more queue structures in a data processing system may include a threaded list of frames which are enqueued or dequeued from the list in accordance with four instructions wherein each list is tied to a so-called lock or control frame with synchronization for multiple processing units. Multiple lock frames and accordingly multiple lists of frames may be coupled in the system for the purpose of accomplishing the various tasks necessary.

Abstract: The performance of a scientific ADD instruction is improved by storing the mantissas of both operands in each of two random access memories, selecting the mantissa with the smaller exponent, shifting that mantissa and performing the ADD operation of adding the mantissas in one machine cycle.

Abstract: Mantissa results of floating point operations are truncated to words of 24 bits each by storing the 64 bit mantissa result in a first address location of a random access memory, and storing binary ZEROs in the 48 least significant bit positions of a second address location of the random access memory. The mantissa result is truncated by addressing the high order 24 bits at the first address location and the 48 binary ZEROs at the second address location.

Abstract: In a system which includes a common bus to which a plurality of units are connected for the transfer of information, such as a data processing system, information may be transferred by the highest priority unit during an asynchronously generated bus transfer cycle. Logic is provided for enabling a first unit, such as a central processor, to make a multiple fetch request of a second unit, such as a memory, during a first transfer cycle. The multiple fetch request requests the second unit to transfer multiple parts of data to the first unit during multiple further transfer cycles, wherein one part of data is transferred in each further transfer cycle. Logic is provided in the second unit to enable the second unit to indicate to the first unit, except during the last further transfer cycle, that each further transfer cycle will be followed by another further transfer cycle.

Abstract: A control store coupled with a central processing unit to transfer information over a common electrical bus and coupled to transfer information over a private interface between the control store and unit. The control store includes firmware words for providing additional control of the unit, which also has a control memory for controlling the operation of the unit. The private interface is used to transfer addressed firmware words from the control store to the unit for use by the unit including generating the next address to be used by the control store, which next address is also provided from the unit to the control store over the private interface. Such private interface is also used to transfer the results of one or more tests performed by the unit, which results indicate which of at least two alternative addresses are to be used by the control store.

Abstract: A data processing unit's request to a data processing device for the transfer of control and processing of an operation in response to an instruction from the unit, is stalled by the device, dependent on the type of instruction, for a period of time, also dependent on the type of instruction, until the device is ready to process such operation. A shift register arrangement is used in the device, which, dependent on the indicia stored therein, which indicia are appropriately loaded in such register dependent on the type of instruction, is used to delay a response to the unit by requesting the unit to make another request to the device to process the operation called for by the instruction.

Abstract: A final effective address of an operand is generated in a microprogrammed data processing system by use of a base address register which may include an unindexed address, an index register which may include an indexed address value, an instruction register which may include an instruction word, which instruction word provides control over the addressing of a control store dependent upon the state of a selected one of a plurality of test conditions. One of the test conditions indicating whether some of the addressing values used in the generation of the effective address are in a short address format or in a long address format. The address control store word provides signals for controlling the operation of the system, including the branch in between such major operations as instruction fetching, addressing, reading, writing, and execution as well as branching between minor operations which are included in the major operations.

Abstract: A harnessing device formed by a locking head and an attached webbed strap. The head contains oppositely positioned locking tangs in a guide channel that receives the strap after encirclement of items to be harnessed. The tangs engage abutments of the webbed strap for adjustable retention of the harnessed items. The strap is advantageously molded of a stretch reorientable material. Stretching produces a relatively thin and strengthened web which resists penetration by the locking tangs and reduces the possibility of failure by fracture or reverse rotation. The inclusion of the relatively thin web also promotes homogeniety during molding and avoids imperfections that can cause failure in other types of straps.

Abstract: Interrupt service is enabled for either a real-time clock or watchdog timer time out condition. A mode register is provided to effectively enable or disable the interrupt apparatus and if enabled is coupled to enable a service register in response to repetitively occurring clock pulses. Each time the service register is enabled, a counter is changed in value until a predetermined value is indicated at which time interrupt service is enabled at an interrupt level specified by the operator. Further, facilities are provided for presetting the value of the counter in an expeditious manner.

Abstract: A data processing system for providing word, byte or bit addressing. A word location in a memory device may be addressed based upon the contents of a base address register. Indirect addressing may be provided to another word location based upon a word index value in an index register. Effective byte or bit addressing of the addressed word is provided in response to byte and bit index values which are produced by means of the index register. An instruction word indicates the type of addressing and directs the use of different control words included in a control storage device in order to implement the desired operation.

Abstract: A plurality of trap save areas are linked to form a pool of such areas from which an area may be loaded with context from various sources in response to a trap condition, such as the addressing of unuseable memory, the loaded area unlinked from the pool, and various pointers changed to reflect such unlinking. The unlinked area is associated with the process which was executing at the time of the occurrence of the trap condition by effectively being coupled to the interrupt level of such process. Independent of the interrupt level, a trap handler routine, specific to the nature of the trap condition, is executed following which the unlinked area is returned to the pool and the various pointers changed to reflect such return.

Abstract: Disclosed is a magnetic disc cartridge of the type in which a magnetic disc assembly is supported for rotation within cartridge covers. Various improvements in the disc cartridge facilitate the manufacture and use thereof. For example, the cartridge inside cover is permanently secured to the cartridge top cover by a series of integral hooks on the inside cover and mating hook anchors on the top cover; a simplified release lever serves to draw the magnetic disc assembly away from the bottom cover when removal of the bottom cover from the remainder of the cartridge is desired; an improved snubber assembly is provided for inhibiting rotation of the disc assembly when the release lever is actuated; and an improved design of the hub which forms a part of the magnetic disc assembly permits the distortion-free operation of the hub, even when made from a synthetic plastic material.

Abstract: A final effective address of an operand is generated in a microprogrammed data processing system by use of a base address register which may include an unindexed address, an index register which may include an index address value, an instruction register which may include an instruction word, which instruction word provides control over the addressing of a control store dependent upon the state of a selected one of a plurality of test conditions. The addressed control store word provides signals for controlling the operation of the system, including the branching between such major operations as instruction fetching, addressing, reading, writing, and execution as well as branching between minor operations which are included in the major operations.

Abstract: In a data processing system, interrupt service is provided for any one of a plurality of interrupt sources which presents an interrupt signal which has a higher interrupt level than that of the currently active source. Interrupt flags are provided for each potential interrupt source, which flags are activated in response to the receipt of an interrupt signal from the interrupt source associated therewith. A scan for the highest interrupt level is made and interrupt service is provided for the interrupt source associated therewith.

Abstract: In a data processing system having a plurality of units coupled for the transfer of information therebetween over a common electrical bus during asynchronously generated information bus transfer cycles, the units are coupled in a priority network and depending upon their respective priority may gain access to the bus before a lower priority unit is so enabled. Each one of the units includes apparatus for responding to a request for the transfer of information from another unit by providing any one of up to three signal responses including a positive acknowledge signal indicating an immediate response, a negative acknowledge signal indicating that the unit will most likely be busy for a relatively extended period of time and a quasi-negative response indicating that the unit will probably be ready during the next asynchronously generated bus transfer cycle.

Abstract: A data processing system having a plurality of interrupt sources coupled to provide interrupt handling of a process currently executing at a specified interrupt level. A level change signal which may be generated by the process itself may change the specified level of such process to another level which may make such process less interruptable to other interrupt sources. The level change provided takes place without interrupting the execution of such process.