Abstract: A technique for use in an I/O channel to increase bus bandwidth during DMA data transfers between main system memory and a communication link is disclosed, including a pair of buffers, a plurality of counters adapted to selectively contain a count of data increments therein, and enhanced DMA control logic for monitoring buffer data content amount, and at a predetermined time during a given transfer initiating a bus arbitration so that it is completed simultaneously with the given transfer, thereby enabling the next data transfer from the buffer in use to immediately commence.

Abstract: A data processing system having an instruction execution circuit that executes a first type of instruction. Also included is a fetch circuit that fetches instructions from a memory and fetches data from the memory in response to a second type of instruction. An instruction decoder is included that decodes fetched instructions and dispatches instructions of the first type to an instruction queueing circuit. The instruction decoder further dispatches instructions of the second type to the fetching circuit. The instruction queueing circuit includes the capability to store decoded instructions of the first type while tagging these instructions when data required for the execution of these instructions has not been fetched. The instruction queueing circuit further clears these tags of these instructions of the first type when data that is required for the execution has been fetched. The instruction queueing circuit serially provides the untagged instructions of the first type to the instruction execution circuit.

Abstract: A method and apparatus are described for expanding the capability of an instruction prefetch buffer. The method and apparatus enables the instruction prefetch buffer to distinguish between old prefetches that occurred before a branch in an instruction stream and new prefetches which occurred after the branch in the instruction stream. A control tag is generated each time a request for an instruction is sent to a storage. The returning instruction has appended thereto the original control tag which is then compared to the current value of control tag in the instruction prefetch buffer. If the two values match, then this is an indication that a branch has not occurred and the instruction is still required. However, if the two values of the control tag are not equal, then this is an indication that a branch in the instruction stream has occurred and that the instruction being sent from storage to the buffer is no longer required.

Abstract: An interface circuit for providing an interface with the parallel data bus that transfers information in a multiple of formats. The interface includes a control circuit that receives or sends control signals from or to the parallel bus to regulate the data transfer and to specify one of the plurality of formats. An addressing circuit, connected to the control circuit, is provided for computing addresses for each of the data received or sent according to the specified format. An accessing circuit connected to the bus, control and address circuits is provided to store or retrieve data from or to the bus according to the computed data addresses. This interface provides a means to serialize data when, in one format, the first word of a data transfer is provided on one part of the data bus but, in a second format, the first data word is provided on another part of the data bus.

Abstract: A data processing system including at least one storage device for storing and retrieving data and connected to a storage device interface that controls the storing and retrieving of data from the storage device and further includes a data buffer for storing data retrieved from or being stored in the storage device. The data processing system includes a storage device driver that receives storage access commands from a processor, provides commands to the interface in response to these commands to the access commands from the processor and also provides commands for data not requested by the processor. The commands for data not requested by the processor provide for the temporary storage of data in the storage device interface data buffer. This data not requested by the processor is retrieved in anticipation of commands to be sent by the processor. The storage driver manages this buffer to optimize the amount of storage dedicated to the storage of data for these anticipatory commands.

Abstract: A mask generation circuit for generating a bit mask sequence of 2.sup.N bits including a first logic circuit having a single level of combinational logic for receiving an N bit indication of the bit mask sequence and for providing an output of 2.sup.q plus 2.sup.P signals to a second logic circuit that includes 2.sup.P identical logical units of not more than 2 levels of combinational logic each connected in parallel and each unit including 2.sup.q -1 repeating circuit sets. These units are connected to receive the signals from the first logic circuit and provide therefrom the ibt mask sequence. In one embodiment of the present invention, a bit mask generator is provided that includes a first edge generator circuit and a second edge generator circuit where each of the edge generator circuits are provided N bit indications indicating the binary digital sequence transition point.

Abstract: A data processing system including a circuit for storing a sequence of instructions, a circuit for determining if the instruction sequence includes a branch instruction, a circuit for storing a sequence of branch target instructions in response to the determination of the existence of a branch instruction in the stored sequence of instructions, a circuit for dispatching instructions in sequence after the branch instruction to a processor to be executed on condition that a branch is to be taken before a determination of whether said branch will be taken and simultaneously for determining if the branch is to be taken, any circuit for directing the processor to execute the instructions in sequence after the branch if the branch is not taken, or, if the branch is to be taken, for dispatching the branch target instruction sequence to the processor for execution.

Abstract: A data processing system including a data cache with the capability to selectively zero the contents of the data cache. The invention includes a multiplexor arranged to provide a parallel data output that is greater than the parallel data input from either a central processing unit or from a memory that are each connected to access the data cache. This multiplexor is selectively controlled to provide a parallel data output of zeroes upon the decoding of a specific zeroing instruction.

Abstract: A clocking circuit connected to a processor for regulating processor operation and including a control circuit that produces a clock signal at a first frequency or for producing a clock signal at a designated one of a plurality of other selectable frequencies in response to a change signal from the processor. The control circuit is connected to a designating circuit that provides a signal to the control circuit to designate one of the selectable frequencies. In the preferred embodiment, the clocking circuit includes a register addressable by the processor and a frequency generator that generates several signals having unique frequencies. The processor may designate one of the frequencies as the clocking frequency by providing the appropriate data to the register. Upon the occurrence of an external event such as a DMA request or an interrupt, the control circuit will provide the clocking signal at a predetermined frequency.

Abstract: A data processing system including an instruction storage buffer for storing a sequence of instructions requiring an operation by at least two processors. The two processors are provided that execute instructions from the instruction storage buffer. An instruction dispatch circuit is provided that dispatches the instructions to the processors. At least one processor includes the capability to execute dispatched instructions before the execution of a preceding instruction in the instruction sequence by another processor. Also, at least one processor includes the capability to delay execution of an interruptable instruction until the instruction can be executed in its appropriate sequential order in the sequence. Also, upon the occurrence of the interrupt, the processors include the capability to purge the instruction storage buffer in order that the interrupt software instructions may be stored for execution.

Abstract: In a data processing system, a method for performing a series of operation sequence results and providing such results including the steps of (1) computing the results for each sequence of operations consecutively and (2) reading the results for the proceeding computations during the computation of a current operation result. This method further includes the use of registers for the temporary storage of the sequence results. During the computation of the operation sequence results, other registers are used in performing the sequence operations. The operations store parameters in a progressive fashion. In other words, the initial operations are performed in one set of registers while the final result from the sequence operation is stored in a different register. The result of a previous operation sequence computation is read from a register that is not being used during the computation of the current sequence operation.

Abstract: In accordance with the teachings of this invention a method for positioning components of input/output circuits is provided. These components are positioned on a semiconductor substrate. The semiconductor substrate includes other than input/output circuits. Each input/output circuit is provided for processing a single bit of information within a data word containing multiple bits. The method includes the step of (1) dividing each input/output circuit into groups containing similar functional subcomponents; (2) forming a vertical column of subcomponents for each input/output circuit and connecting these subcomponents to perform the function; (3) placing said columns in adjacency to form a plurality of columns with like subcomponents immediately adjacent to each other forming row groups of said like subcomponents; and (4) forming guard rings around the subcomponent row groups if required. Also in accordance with this invention, a group of input/output circuits is provided.

Abstract: The present invention is directed to a conventional data processing system having a CPU and at least one external unit such as the main storage unit acquiring data from or providing data to the CPU and I/O bus for the transfer of data between the CPU and the external unit. The apparatus of the present invention provides for transfers to and from this external unit, e.g., main storage being overlapped with a register to register data transfer routinely carried out in the CPU to implement various CPU operations and computation functions. The CPU includes apparatus for transferring data to or from said external unit over the I/O bus during synchronized time cycles. The CPU also includes local storage apparatus which comprise a plurality of registers as well as expedients for transferring data from register to register. Control apparatus controls the register to register data transfer so that such transfers are conducted during time cycles coincident with the transfer of data to or from the external storage unit.