Abstract: Apparatus and techniques for performing JTAG testing on production devices and systems through industry standard interfaces. The devices employ processors configured to receive packetized test input data from a tester over a standard communication interface such as a USB or Ethernet port and perform associated testing operations defined by the test input data, such as JTAG-compliant testing. This is facilitated, in part, via use of a bridge and one or more DFx handlers, with the bridge operating as an interface between the DFx handlers and a bus and/or interconnect over which test input and result data is transferred via the standard communication interface. The techniques enable testing such as JTAG testing to be performed on fully-assembled devices and systems without requiring the use of dedicated test or debug ports.

Abstract: Apparatus and techniques for performing JTAG testing on production devices and systems through industry standard interfaces. The devices employ processors configured to receive packetized test input data from a tester over a standard communication interface such as a USB or Ethernet port and perform associated testing operations defined by the test input data, such as JTAG-compliant testing. This is facilitated, in part, via use of a bridge and one or more DFx handlers, with the bridge operating as an interface between the DFx handlers and a bus and/or interconnect over which test input and result data is transferred via the standard communication interface. The techniques enable testing such as JTAG testing to be performed on fully-assembled devices and systems without requiring the use of dedicated test or debug ports.

Abstract: A computing system performs non-restoring division. Quotient selection logic selects quotient digits that are used to produce a final quotient. The quotient digits are selected according to a predetermined relationship among certain bits of the divisor and the partial remainder. Only non-zero quotient digits are selected. A quotient accumulator combines each selected quotient digit with a current partial quotient concurrently while each quotient digit is selected. The quotient digits are selected and combined until the final quotient is produced.

Abstract: A cache coherency scheme in a multiprocessor computer system allows data sharing between caches at a fast rate. A new cache coherency state is introduced which allows a processor pair to more effectively share data and eliminate bus transfers thereby improving system throughput. The transfer of data is accomplished by the returning a portion of a preselected data block pursuant to either a read or a read for ownership request by a first one of the processors of the processor pair by the second processor of the processor pair. The ownership of the portion of the preselected data block is shared by the processor pair. Both processors set an indicator to denote that the preselected data block is an incomplete data block.

Abstract: The set-prediction cache memory system comprises an extension of a set-associative cache memory system which operates in parallel to the set-associative structure to increase the overall speed of the cache memory while maintaining its performance. The set prediction cache memory system includes a plurality of data RAMs and a plurality of tag RAMs to store data and data tags, respectively. Also included in the system are tag store comparators to compare the tag data contained in a specific tag RAM location with a second index comprising a predetermined second portion of a main memory address.

Abstract: A master-slave processor interface protocol transfers a plurality of instructions from a master processor to a slave processor. Each instruction has an opcode and a set of operands. The interface includes a micro-engine which sends the opcode for each of the instructions to be executed to the slave processor and stores the opcode in a first buffer in the slave processor. A second micro-engine operates the master processor to fetch and process the set of operands for each of the instructions to be executed by the slave processor in the order of the opcode delivery to the first buffer. A third micro-engine delivers a signal to the slave processor when the master processor is ready to deliver the operands for an instruction. The opcode associated with the operands ready to be delivered is then moved from the first buffer to a second buffer upon receiving the signal from the master processor. The processed set of operands are then sent to the second buffer and the instruction is executed.

Abstract: An apparatus for performing high performance multiplication in a computer central processor unit which implements a sliced design configuration. Each slice changes its "personality" by virtue of receiving consecutive bits of the multiplicand. The receipt of consecutive bits by each slice eliminates the need for the interconnection of successive slices in separate chips. Thus, the apparatus allows the avoidance of significant timing delays, inherent in such interchip connections, which diminish computer system multiplication performance, and allows the multiply cycle time to be as fast as a latch-to-latch transfer across chips. Each slice may include a binary multiplier for forming a product of two numbers on an iterative basis, an accumulator connected to the multiplier for adding the products from the multiplier, and a carry-out register connected to the accumulator for storing carry-out data.

Abstract: A high performance adder is provided including a predicted carry look ahead coupled between a lower order adder and a higher order adder of the high performance adder. The predicted carry look ahead provides as an input to the carry input of the adder a prediction of a carry bit produced by the adding of lower order bits of two addends by the lower order adder. By this arrangement, the highest order adder can operate on the highest order bits of two addends with a predicted carry and without having to wait for the results of the carries that occur in the lower order bits.

Abstract: A method and apparatus for performing high performance multiplication in a computer central processor unit which implements a sliced design configuration. Each slice changes its "personality" by virtue of receiving consecutive bits of the multiplicand. The receipt of consecutive bits by each slice eliminates the need for the interconnection of successive slices in separate chips. Thus, the apparatus allows the avoidance of significant timing delays, inherent in such interchip connections, which diminish computer system multiplication performance, and allows the multiply cycle time to be as fast as a latch-to-latch transfer across chips.

Abstract: The invention is directed to an apparatus and method for predicting the number of bits which must be taken into account to normalize the result of a floating point addition or subtraction. The apparatus and method employ: a low precision floating point adder/subtractor, a priority encoder that determines the position of the most significant non-zero bit to generate the normalization amount and preround logic which pre-shifts a rounding bit in the opposite direction of normalization. The method and apparatus operate in parallel with a full precision floating point adder to eliminate the need for a full-precision floating point normalization calculation and rounding computation in most circumstances. The normalization amount for successful low-precision floating-point addition/subtraction is calculated by the time the full-precision floating-point addition/subtraction stage occurs.