Hewlett-Packard Company

Hewlett-Packard Development Company, L.p.

Other

Intel Corporation

Hewlett-Packard Corporation

Joel D Lamb

Ruby B Lee

Kevin Safford

Patrick Knebel

Donald Charles Soltis, Jr

Russell C Brockmann

Stephen R Undy

Charles R Dowdell

Leon Jacob Sigal

Christopher Allan Poirier

Russell W Mason

Kevin Liao

The present invention is a method for implementing two architectures on a single chip. The method uses a fetch engine to retrieve instructions. If the instructions are macroinstructions, then it decodes the macroinstructions into microinstructions, and then bundles those microinstructions using a bundler, within an emulation engine. The bundles are issued in parallel and dispatched to the execution engine and contain pre-decode bits so that the execution engine treats them as microinstructions. Before being transferred to the execution engine, the instructions may be held in a buffer. The method also selects between bundled microinstructions from the emulation engine and native microinstructions coming directly from the fetch engine, by using a multiplexer or other means. Both native microinstructions and bundled microinstructions may be held in the buffer. The method also sends additional information to the execution engine.

Method and apparatus for implementing two architectures in a chip

The present invention is a method for implementing two architectures on a single chip. The method uses a fetch engine to retrieve instructions. If the instructions are macroinstructions, then it decodes the macroinstructions into microinstructions, and then bundles those microinstructions using a bundler, within an emulation engine. The bundles are issued in parallel and dispatched to the execution engine and contain pre-decode bits so that the execution engine treats them as microinstructions. Before being transferred to the execution engine, the instructions may be held in a buffer. The method also selects between bundled microinstructions from the emulation engine and native microinstructions coming directly from the fetch engine, by using a multiplexor or other means. Both native microinstructions and bundled microinstructions may be held in the buffer. The method also sends additional information to the execution engine.

Method and apparatus for implementing two architectures in a chip using bundles that contain microinstructions and template information

An apparatus and method for determining register dependency in multiple architecture system. The system includes a microprocessor emulating an emulated instruction set using a native instruction set where the microprocessor contains at least one register. An execution engine provides the native instructions where each native instruction contains at least one register identifier. Flags are provided to each native instruction where each flag indicates whether a register identifier is valid. A bundler checks for dependency among the valid register identifiers in the native instructions.

Determining register dependency in multiple architecture systems

A method and apparatus are provided for sensing and temporarily latching data signals from memory cells. According to one embodiment, data signals are sensed from memory cells and temporarily latched on an output signal. During a first phase of a clock cycle, multiple input bit-lines are precharged. Subsequently, a discharged input bit-line is sensed during a second phase of the clock cycle. Responsive to the sensing step, the output signal is set to a first state and maintained for at least one clock cycle. According to another embodiment, a multiple input bit-line detecting circuit includes multiple input bit-lines, precharge logic, and output logic. The multiple input bit-lines are configured to be coupled to a bit-line hierarchy of a memory device. The precharge logic is coupled to each of the input bit-lines and is configured to precharge each of the input bit-lines during a first phase of a clock cycle. The output logic is operatively coupled to the multiple input bit-lines to set an output signal to a first state and maintain the first state on the output signal for at least one clock cycle in response to one or more of the input bit-lines being discharged.

Multiple input bit-line detection with phase stealing latch in a memory design

A N-bit by N-bit multiplication apparatus having the ability to select a part of the multiplication result for storage into a result register N-bits wide. A first embodiment of the invention allows a sequence of n-bits from the N-bit by N-bit multiply result to be stored into an N-bit wide register. N+1 to 1 multiplexors are utilized to select which of the multiply result bits are stored into the result register in response to a computer instruction. The second preferred embodiment utilizes multiplexors having fewer than N+1 inputs to select discrete subsets of the multiply result bits for storage into the N-bit wide result register. In this manner, less complex multiplexors are required which take less chip area to implement. The third preferred embodiment utilizes multiple sets of multiplexors to select multiple subresults generated by a parallel multiplication operation. The multiple subresults are stored in a single result register. By allowing subresults to be selected and stored as part of the multiply operation, a multiply apparatus according to the present invention is more time and instruction efficient than prior art devices.

Computer multiply instruction with a subresult selection option

A computer instruction and apparatus for performing a N-bit by N-bit multiplication and having the ability to select a part of the multiplication result for storage into a result register N-bits wide. A first embodiment of the invention allows a sequence of n-bits from the N-bit by N-bit multiply result to be stored into an N-bit wide register. N+1 to 1 multiplexors are utilized to select which of the multiply result bits are stored into the result register in response to a multiply and select computer instruction. The second preferred embodiment utilizes multiplexors having fewer than N+1 inputs to select discrete subsets of the multiply result bits for storage into the N-bit wide result register. In this manner, less complex multiplexors are required which take less chip area to implement. The third preferred embodiment utilizes multiple sets of multiplexors to select multiple subresults generated by a parallel multiplication operation. The multiple subresults are stored in a single result register. By allowing subresults to be selected and stored as part of the multiply operation, a multiply apparatus according to the present invention is more time and instruction efficient than prior art devices.

Integer multiply instructions incorporating a subresult selection option

A computer system provides handling of positive and negative overflow. A first arithmetic operation is performed on a first n-bit unsigned binary operand and a second n-bit signed binary operand to produce an n-bit unsigned binary result. Overflow detection logic circuitry within the arithmetic logic unit detects positive overflow or negative overflow resulting from the arithmetic operation. When there is a positive overflow, saturation logic replaces the output of the two's complement adder with a value of 2.sup.n-1. When there is a negative overflow, the saturation logic replaces the output of the two's complement adder with a value of 0. In an alternate embodiment, a first arithmetic operation is performed on a first n-bit signed binary operand and a second n-bit signed binary operand to produce an n-bit positive signed binary result. For example the arithmetic operation is an addition or subtraction performed by a two's complement adder. In the alternate embodiment, overflow detection logic circuitry within the arithmetic logic unit detects positive overflow or negative overflow resulting from the arithmetic operation. When there is a positive overflow, saturation logic replaces the output of the two's complement adder with a value of 2.sup.n-1 -1. When there is a negative overflow, the saturation logic replaces the output of the two's complement adder with a value of 0.

Efficient hardware handling of positive and negative overflow resulting

An apparatus for combining the contents of an X register, shifted by m places, with the contents of a Y register to generate a result Z. The functional unit can also be configured to perform parallel operations on sub-operands in the X and Y registers. The division of the apparatus into sub-operands is controlled by a mask which specifies the boundary of the sub-operands. The shifting operation is accomplished by multiplexers that connect the p.sup.th bit of the X register to the adder stage that operates on bit Y.sub.p-m of the Y register. Circuitry is provided at the boundary of the sub-operands to prevent the bit signals corresponding to the X register from being routed across a sub-operand boundary. Similarly, circuitry is provided for preventing the carry output of an adder stage that operates on one sub-operand from being propagated to an adder stage that operates on another sub-operand.

Parallel shift and add circuit and method

A clocking methodology for VLSI chips which uses global overlapping clocks, locally or remotely generated non-overlapping clocks, combined with pipeline control signals to generate signals which control the transfer gates of registers in a pipeline. The signals which control the transfer gates of the registers in a pipeline maintain the important timing relationships of the non-overlapping clock signals combined with the control signals. The global overlapping clocks are used where possible to provide timing advantages, while the non-overlapping clocks are used to eliminate race conditions as data propagates down a pipeline of transparent registers. Overlapping clock signals are used whenever such race conditions can be avoided, as at the ends of the registered pipeline, with the resultant performance improvement.

Qualified non-overlapping clock generator to provide control lines with

In a lookahead adder of the type wherein carry signals for successive stages of the adder are derived by a pyramid of hierarchically-arranged logic circuits, supplemented by carry signals from intermediate ones of the adder stages. The need to rely on such intermediate carry signals is dispensed with by additional non-hierarchically-arranged logic circuits whose outputs provide the information previously derived from intermediate carry outputs.

Lookahead adder

A clocking methodology for VLSI chips which uses global overlapping clocks plus locally or remotely generated non-overlapping clocks. Two overlapping clocks and two non-overlapping clocks are thus available in each block of a chip for use as timing edges. The global overlapping clocks are used where possible to provide timing advantages, while the non-overlapping clocks are used to eliminate race conditions as data propagates down a pipeline of transparent registers. Generally, one non-overlapping clock has an edge which must fall before a clock edge of the other non-overlapping clock rises and an edge which must rise after a clock edge of the other non-overlapping clock falls. These signals may be applied to adjacent stages to prevent race conditions; however, the 'dead' time between the falling of one clock edge and the rising of the other clock edge has performance costs. Overlapping clocks are used whenever such race conditions can be avoided, as at the ends of the register pipeline, with the resultant performance improvement. The non-overlapping clock signals are preferably derived from the overlapping clock signals inside each block rather than globally so that it is easier to control the skew between phases of the non-overlapping clock signals. Such use of local non-overlapping clock generators in each block also reduces the amount of capacitive loading on the global overlapping clock network, thereby allowing faster edges and smaller skews on the global overlapping clock which further improves the performance of critical timing paths which use the global overlapping clock.

VLSI clocking system using both overlapping and non-overlapping clocks

A lookahead adder with identical logic gates in all but the first of its lookahead sections. All such identical gates implement the logic function M=X+Y.Z.

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Fort Collins, CO, United States of America

Joel D Lamb