Abstract: A three-dimensional (3-D) processor system includes a first processor chip and a second processor chip in a stacked configuration. The first processor chip includes a first processor having a first set of state registers. The second processor chip includes a second processor having a second set of state registers that corresponds to the first set of state registers. The first and second processors are connected through vertical connections between the first and second processor chips. A mode control circuit operates the processor system in one of a plurality of operating modes. In one mode of operation, the first processor is active and the second processor is inactive, and the first processor operates at a speed greater than a maximum safe speed of the first processor, and the first processor uses the second set of state registers of the second processor to checkpoint a state of the first processor.

Abstract: A three-dimensional (3-D) processor system includes a first processor chip and a second processor chip in a stacked configuration. The first processor chip includes a first processor having a first set of state registers. The second processor chip includes a second processor having a second set of state registers that corresponds to the first set of state registers. The first and second processors are connected through vertical connections between the first and second processor chips. A mode control circuit operates the processor system in one of a plurality of operating modes. In one mode of operation, the first processor is active and the second processor is inactive, and the first processor operates at a speed greater than a maximum safe speed of the first processor, and the first processor uses the second set of state registers of the second processor to checkpoint a state of the first processor.

Abstract: Three-dimensional (3-D) processor structures are provided which are constructed by connecting processors in a stacked configuration. For example, a processor system includes a first processor chip comprising a first processor, and a second processor chip comprising a second processor. The first and second processor chips are connected in a stacked configuration with the first and second processors connected through vertical connections between the first and second processor chips. The processor system further includes a mode control circuit to selectively configure the first and second processors of the first and second processor chips to operate in one of a plurality of operating modes, wherein the processors can be selectively configured to operate independently, to aggregate resources, to share resources, and/or be combined to form a single processor image.

Abstract: Three-dimensional (3-D) processor devices are provided, which are constructed by connecting processors in a stacked configuration. For instance, a processor system includes a first processor chip comprising a first processor and a second processor chip comprising a second processor. The first and second processor chips are connected in a stacked configuration with the first and second processors connected through vertical connections between the first and second processor chips. The processor system further includes a mode control circuit to selectively operate the processor system in one of a plurality of operating modes. For example, in a one mode of operation, the first and second processors are configured to implement a run-ahead function, wherein the first processor operates a primary thread of execution and the second processor operates a run-ahead thread of execution.

Abstract: Three-dimensional (3-D) processor structures are provided which are constructed by connecting processors in a stacked configuration. For example, a processor system includes a first processor chip comprising a first processor, and a second processor chip comprising a second processor. The first and second processor chips are connected in a stacked configuration with the first and second processors connected through vertical connections between the first and second processor chips. The processor system further includes a mode control circuit to selectively configure the first and second processors of the first and second processor chips to operate in one of a plurality of operating modes, wherein the processors can be selectively configured to operate independently, to aggregate resources, to share resources, and/or be combined to form a single processor image.

Abstract: Three-dimensional (3-D) processor devices are provided, which are constructed by connecting processors in a stacked configuration. For instance, a processor system includes a first processor chip comprising a first processor and a second processor chip comprising a second processor. The first and second processor chips are connected in a stacked configuration with the first and second processors connected through vertical connections between the first and second processor chips. The processor system further includes a mode control circuit to selectively operate the processor system in one of a plurality of operating modes. For example, in a one mode of operation, the first and second processors are configured to implement a run-ahead function, wherein the first processor operates a primary thread of execution and the second processor operates a run-ahead thread of execution.

Abstract: A method comprising receiving a branch instruction, decoding a branch address and the branch instruction, executing a branch action associated with the branch address, determining whether a branch associated with the branch action was taken, and saving an identifier of the branch instruction and in indicator that the branch action was taken in a prefetch history table responsive to determining that the branch associated with the branch action was taken.

Abstract: A method for branch prediction, the method comprising, receiving a load instruction including a first data location in a first memory area, retrieving data including a branch address and a target address from the first data location, and saving the data in a branch prediction memory, or receiving an unload instruction including the first data location in the first memory area, retrieving data including a branch address and a target address from the branch prediction memory, and saving the data in the first data location.

Abstract: A method comprising receiving a branch instruction, decoding a branch address and the branch instruction, executing a branch action associated with the branch address, determining whether a branch associated with the branch action was taken, and saving an identifier of the branch instruction and in indicator that the branch action was taken in a prefetch history table responsive to determining that the branch associated with the branch action was taken.

Abstract: A method for branch prediction, the method comprising, receiving a branch wrong guess instruction having a branch wrong guess instruction address and data including an opcode and a branch target address, determining whether the branch wrong guess instruction was predicted by a branch prediction mechanism, sending the branch wrong guess instruction to an execution unit responsive to determining that the branch wrong guess instruction was predicted by the branch prediction mechanism, and receiving and decoding instructions at the branch target address.

Abstract: A method for branch prediction, the method comprising, receiving a load instruction including a first data location in a first memory area, retrieving data including a branch address and a target address from the first data location data location, and saving the data in a branch prediction memory.

Abstract: A two level branch history table (TLBHT) is substantially improved by providing a mechanism to prefetch entries from the very large second level branch history table (L2 BHT) into the active (very fast) first level branch history table (L1 BHT) before the processor uses them in the branch prediction process and at the same time prefetch cache misses into the instruction cache. The mechanism prefetches entries from the very large L2 BHT into the very fast L1 BHT before the processor uses them in the branch prediction process. A TLBHT is successful because it can prefetch branch entries into the L1 BHT sufficiently ahead of the time the entry is needed. This feature of the TLBHT is also used to prefetch instructions into the cache ahead of their use. In fact, the timeliness of the prefetches produced by the TLBHT can be used to remove most of the cycle time penalty incurred by cache misses.

Abstract: A mechanism is described that predicts the usefulness of a prefetching instruction during the instruction's decode cycle. Prefetching instructions that are predicted as useful (prefetch useful data) are sent to an execution unit of the processor for execution, while instructions that are predicted as not useful are discarded. The prediction regarding the usefulness of a prefetching instructions is performed utilizing a branch prediction mask contained in the branch history mechanism. This mask is compared to information contained in the prefetching instruction that records the branch path between the prefetching instruction and actual use of the data. Both instructions and data can be prefetched using this mechanism.

Abstract: A two level branch history table (TLBHT) is substantially improved by providing a mechanism to prefetch entries from the very large second level branch history table (L2 BHT) into the active (very fast) first level branch history table (L1 BHT) before the processor uses them in the branch prediction process and at the same time prefetch cache misses into the instruction cache. The mechanism prefetches entries from the very large L2 BHT into the very fast L1 BHT before the processor uses them in the branch prediction process. A TLBHT is successful because it can prefetch branch entries into the L1 BHT sufficiently ahead of the time the entry is needed. This feature of the TLBHT is also used to prefetch instructions into the cache ahead of their use. In fact, the timeliness of the prefetches produced by the TLBHT can be used to remove most of the cycle time penalty incurred by cache misses.

Abstract: A mechanism is described that prefetches instructions and data into the cache using a branch instruction as a prefetch trigger. The prefetch is initiated if the predicted execution path after the branch instruction matches the previously seen execution path. This match of the execution paths is determined using a branch history queue that records the branch outcomes (taken/not taken) of the branches in the program. For each branch in this queue, a branch history mask records the outcomes of the next N branches and serves as an encoding of the execution path following the branch instruction. The branch instruction along with the mask is associated with a prefetch address (instruction or data address) and is used for triggering prefetches in the future when the branch is executed again. A mechanism is also described to improve the timeliness of a prefetch by suitably adjusting the value of N after observing the usefulness of the prefetched instructions or data.

Abstract: A floating gate is inserted into the gate stack of an EEPROM cell. For an N channel EEPROM device, the floating gate is composed of a material having a conduction band edge (or fermi energy in the case of a metal or composite that includes a metal) at least one and preferably several kT electron volts below the conduction band edge of the channel region. The floating gate material thus has a larger electron affinity than the material of the channel region. This allows the insulator separating the floating gate and the channel to be made suitable thin (less than 100 angstroms) to reduce the writing voltage and to increase the number of write cycles that can be done without failure, without having charge stored on the floating gate tunnel back out to the channel region during read operations.

Abstract: An artificial neural synapse (10) is constructed to function as a modifiable excitatory synapse. In accordance with an embodiment of the invention the synapse is fabricated as a silicon MOSFET that is modified to have ions within a gate oxide. The ions, such as lithium, sodium, potassium or fluoride ions, are selected for their ability to drift within the gate oxide under the influence of an applied electric field. In response to a positive voltage applied to a gate terminal of the device, positively charged ions, such as sodium or potassium ions, drift to a silicon/silicon dioxide interface, causing an increase in current flow through the device. The invention also pertains to assemblages of such devices that are interconnected to form an artificial neuron and to assemblages of such artificial neurons that form an artificial neural network.

Abstract: A neural network utilizing the threshold characteristics of a semiconductor device as the various memory elements of the network. Each memory element comprises a complementary pair of MOSFETs in which the threshold voltage is adjusted as a function of the input voltage to the element. The network is able to learn by example using a local learning algorithm. The network includes a series of output amplifiers in which the output is provided by the sum of the outputs of a series of learning elements coupled to the amplifier. The output of each learning element is the difference between the input signal to each learning element and an individual learning threshold at each input. The learning is accomplished by charge trapping in the insulator of each individual input MOSFET pair. The thresholds of each transistor automatically adjust to both the input and output voltages to learn the desired state.

Abstract: Covering metal test pads of a passivated integrated circuit process intermediate wafer or completed integrated circuit chip-to-test, with a thin conductive overlayer, and then accessing the test pads through the passivation layer and conductive overlayer, by a pulsed laser to provide voltage-modulated photon-assisted tunneling through the insulation layer, to the conductive overlayer as an electron current, and detecting the resulting electron current, provides a nondestructive test of integrated circuits. The passivation, normally present to protect the integrated circuit, also lowers the threshold for photoelectron emission. The conductive overlayer acts as a photoelectron collector for the detector. A chip-to-test which is properly designed for photon assisted tunneling testing has test sites accessible to laser photons even though passivated.

Abstract: In a transistor structure a buried gate positioned in the layer above a conduction channel and below a broad gate which overlaps the source and drain, when the voltages applied to the buried gate and the overlapping gate are varied independently, a potential well between two barriers can be established which permits conduction by the physical mechanism of resonant transmission. The potential well between two barriers required for the resonant transmission mechanism is achieved in one structure by a buried gate under an overlapping gate with both width and separation dimension control and in a second structure using split-buried gate under an overlapping gate that is embossed in the region of the split gate. With gate and separation dimensions of the order of 1000 .ANG. switching speeds of the order of 10.sup.-12 seconds are achieved.