Abstract: A variable logic circuit comprises a memory cell, a transistor which turns on or off depending on data stored in the memory cell, a transistor which is connected in series to the above-mentioned transistor and is turned on or off by an input signal, a transistor which produces a voltage depending on the conduction states of the above-mentioned transistors, and transfer means which conducts or does not conduct the produced voltage to the output terminal depending on a select signal.

Abstract: A data transmission method exchanges data between at least first and second electronic devices which are coupled via a plurality of bus lines, where each of the bus lines is terminated via a terminating resistor having one end coupled to a bus line and another end applied with a terminating voltage. The data transmission method includes the steps of (a) setting a high logic level of data to a voltage higher than the terminating voltage and setting a low logic level of the data to a voltage lower than the terminating voltage, and (b) continuously outputting the data from the first electronic device to at least one bus line at a timing determined by a first clock signal by alternately repeating a state where the data is output to the one bus line and a state where an impedance between the first electronic device and the one bus line is set to a high impedance.

Abstract: A programmable logic circuit includes a programmable logic array which generates a plurality of output signals for output from a single port on the programmable logic circuit, and which processes a plurality of input signals received from a single port on the programmable logic circuit. The programmable logic circuit also includes multiplexing means for receiving the plurality of output signals generated by the programmable logic array and for multiplexing the plurality of output signals. An output port outputs, from the programmable logic circuit, the multiplexed plurality of output signals generated by the programmable logic array. An input port receives a multiplexed plurality of input signals, and a demultiplexing means demultiplexes the multiplexed plurality of input signals and configurably communicates the demultiplexed plurality of input signals to the programmable logic array.

Abstract: A pipeline-able asynchronous logic circuit is provided that implements a subfunction of a logic function that is distributed into multiple sequential subfunctions. Each subsequent subfunction is applied to a result of an immediately preceding subfunction of the sequence. The asynchronous logic circuit has an output node and a differential logic circuit connected to the output node via a first path. The differential logic circuit applies a particular subfunction to an inputted signal to produce a result signal. The asynchronous logic circuit also has a sense amplifier that is connected to the output node via a second path which is distinct from the first path. The sense amplifier, in response to being enabled, amplifies the result signal produced by the differential logic circuit. The sense amplifier outputs the amplified result signal onto the output node.

Abstract: A logic block comprised of several transistors is provided. The logic block has several inputs and an output for communicating the result of its logic operation. A precharge device having a clock input is connected to the output of the logic block. The precharge device periodically allows the output of the logic block to become valid. This is accomplished by holding the output of the logic block at a fixed voltage level when the clock input is at a first voltage level, and when the clock input changes to a second voltage level, the precharge device allows the result of the logic function performed by the logic block to appear at the output of the logic block. Also, a charge redistribution prevention device is connected to at least one of the transistors included in the logic block. The charge redistribution prevention device prevents charge redistribution by applying a voltage to at least one of the transistors in the logic block.

Abstract: A logic block comprised of several transistors is provided. The logic block has several inputs and an output for communicating the result of its logic operation. A precharge device having a clock input is connected to the output of the logic block. The precharge device periodically allows the output of the logic block to become valid. This is accomplished by holding the output of the logic block at a fixed voltage level when the clock input is at a first voltage level, and when the clock input changes to a second voltage level, the precharge device allows the result of the logic function performed by the logic block to appear at the output of the logic block. Also, a charge redistribution prevention device is connected to at least one of the transistors included in the logic block. The charge redistribution prevention device prevents charge redistribution by applying a voltage to at least one of the transistors in the logic block.

Abstract: An apparatus and method for decreasing the amount of time necessary to load configuration data into Field Programmable Gate Arrays (FPGAs) or other integrated circuit devices. In a preferred embodiment, serially arrayed FPGAs receive a concatenated stream of data from a common data bus. As a first FPGA reaches a loading-complete state, an enabling token is passed from the first FPGA to an enabling input on the next FPGA. The process repeats until all devices are completely loaded or fully configured.

Abstract: To judge whether or not the number of high-level bits among N (N.ltoreq.2) bits of an input signal is greater than a predetermined number M (1.ltoreq.M<N), a judging circuit has a differential amplifier, N primary MISFETs, M secondary MISFETs, and primary and secondary resistors having the same resistance. Sources of the primary MISFETs are connected to the ground in common. Drains of the primary MISFETs are connected to one end of the primary resistor in common. The other end of the primary resistor is supplied with a power-supply voltage. Gates of the primary MISFETs are supplied with the N bits, respectively. The primary MISFETs have on-currents, respectively, which are equal to one another. An inverted input terminal of the amplifier is connected to the above-mentioned one end of the primary resistor. Sources of the secondary MISFETs are connected to the ground in common. Drains of the secondary MISFETs are connected to one end of the-secondary resistor in common.

Abstract: An input buffer capable of operating at a first power supply voltage level or a second power supply voltage level with the operating voltage level selectable during manufacture. At least one shortable transistor is disposed between the power supply voltage input and a buffer circuit which is connected between an input and an output of the buffer circuit. When the first voltage is the intended operating voltage the at least one shortable transistor is shorted. The first operating voltage level meets the requirements of a CMOS device and the second operating voltage level meets the requirements of a TTL device. The shortable transistor can be either a p-channel or an n-channel transistor and the short can be done by a metal layer short, a polysilicon short, a depletion implant, or with vias during manufacture.

Abstract: A technique for configuring arrays of programmable logic cells, including those associated with FPGA devices, through a novel DRAM-based configuration control structure that enables not only "on-the-fly" alterable chip and similar device reconfigurations, but, where desired, self-modifying reconfigurations for differing functionalities of the devices, eliminating current serious reconfigurability limitations and related problems, while providing significantly enhanced system performance at low cost. A large amount of memory is available internal to the FPGA and is accessed with a small number of pins such that the reconfiguration time is, for example, four orders of magnitude faster than the traditional approaches and at notably low cost.

Abstract: A mixed-mode, overvoltage tolerant input buffer for interfacing to a tristate bus line is disclosed, the input buffer having a bus hold feature for maintaining the state of the input buffer output and bus line when the bus line enters into the tristate mode, the input buffer being capable of suppressing leakage currents from the bus input through the bus hold circuit to the input buffer power supply during overvoltage conditions. The bus hold circuit has a feedback inverter coupled between the output and the bus input for providing a stabilizing feedback signal to the bus input, the inverter being powered by a source voltage which is selectively coupled to the input buffer power supply, the source voltage being isolated from the input buffer power supply during overvoltage conditions.

Abstract: The present invention discloses a circuit to reduce current and voltage spikes when switching inductive loads. The circuit of the present invention achieves this reduction in voltage and current spikes without requiring the prior art's large sizes for the transistors driving the inductive load. The invention results in reduced cost and power consumption. Moreover, the invention's circuit maintains a fast switching time for the transistors driving the inductive load. The invention's circuit comprises a current steering mechanism which directs current to one of the two drivers driving an inductive load. According to the invention, current is directed to the driver coupled to the supply voltage, the driver coupled to ground, or both in different amounts. The current is directed to the drivers such that the effect of flyback voltage caused by switching the inductive load is reduced.

Abstract: In a dynamic random access memory unit, a parity check logic circuit includes a parity signal generating circuit which generates a parity signal for each signal group transmitted on the input/output data bus. For a sequence of data groups on the data bus, a parity signal for each data group is generated, the parity signal combined with a parity signal generated for the previous data group or data groups. For a read operations, a parity signal is generated for each of sequence of retrieved data groups and combined with the parity signal(s) of the previous data groups of the sequence. The resulting parity signal is compared with the parity signal associated with the data group sequence and stored in the memory unit to generate a flag signal when the parity signals are not identical. For a write operation, the resulting parity signal for all the data groups is stored in memory unit at a location associated with the sequence of data groups.

Abstract: A programmable logic array integrated circuit has several regular columns of programmable logic circuitry and a spare column which includes a subset of the programmable logic circuitry that is included in a regular column. In the event of a defect in the circuitry in a regular column that is duplicated in the spare column, the regular column logic functions that are thus duplicated are shifted from column to column so that the spare column circuitry is put to use and the defective regular column circuitry is not used. Regular column functions that are not duplicated in the spare column are not shifted. Data for programming the columns is selectively routed to the columns with or without column shifting, depending on whether that data is for functions that are or are not duplicated in the spare column.

Abstract: An input/output buffer for computer circuitry including a P type transistor device responsive to data signals for selectively furnishing voltage from a first source of potential at a buffer input/output terminal, a first predriver circuit for furnishing data signals from a source to the P type transistor device, the first predriver circuit including circuitry for slowing the application of data signals to the P type transistor device when the buffer input/output terminal is at a high level, a N type transistor device responsive to data signals for selectively furnishing voltage from a second source of potential at the buffer output terminal, a second predriver circuit for furnishing data signals from the source to the N type transistor device, and circuitry for slowing the receipt of data signals at the first predriver circuit.

Abstract: A heterogeneous integrated circuit device comprising a field programmable gate array (FPGA) programmably connected to a mask-defined application specific logic area (ASLA) on an integrated circuit thus providing a flexible low cost alternative to a homogeneous device of one type or the other. By integrating both on a single monolithic IC, the user benefits from both low cost and flexibility. Routing of signals between gate arrays and between the gate arrays and input/output (I/O) circuits is also implemented as a combination of mask-defined and programmably-configured interconnections.

Abstract: In an information processing apparatus including a backboard having a bus for transmitting signals therethrough, at least one module, and a connector to connect the bus to the module, the backboard includes two terminators disposed respectively at both ends of the bus for providing matched termination according to a characteristic impedance of the bus to which the module is connected and a matching resistor disposed between the bus and the module. The matching resistor has a resistance value Rm represented asRm=Z1.multidot.k-Z0/2(0.8<k<1.3)where, Z1 indicates a characteristic impedance of the module, Z0 denotes the characteristic impedance of the bus, and k stands for a coefficient.

Abstract: For an FPGA having a configuration memory arranged in rows and columns, a programmable address decoder with a counter selects the order in which columns of memory cells will be programmed and selects which columns of memory cells are programmed. The decoder structure addresses a particular column only when an address provided by the counter matches an address in the memory cells of the decoder for that column. Bitstreams intended for older devices can be successfully loaded into newer devices. Bitstreams developed for future devices with additional features can be loaded into devices with fewer features, and the additional features are not used. The counter can be set to count not in sequential order so that if extra columns are provided, a defective column of the FPGA controlled by a corresponding column of configuration memory cells can be bypassed.

Abstract: A logic element for a programmable logic device. The logic element includes a look-up table (400) for implementing logical functions, a programmable delay block (415), a storage block (430) configurable as a latch or a flip-flop, and a diagnostic shadow latch (435). A plurality of inputs (410) to the logic element and complements of these inputs are available to control the secondary functions of the storage block (430).

Abstract: An EPLD having improved routing and arithmetic function implementation characteristics. Cascade and carry logic in macrocells allows for rapid implementation of arithmetic functions without unnecessarily tying up device processing and interconnect resources or unnecessarily delaying processing.