Abstract: A programmable logic integrated circuit device has several features which help it perform according to the PCI Special Interest Group's Peripheral Component Interface (“PCI”) signaling protocol. Some of the registers on the device are closely coupled for data input and output to data signal input/output pins of the device. The clock signal input terminals of at least these registers are also closely coupled to the clock signal input pin of the device. Programmable input delay is provided between the data signal input/output pins and the data input terminals of the above-mentioned registers to help compensate for clock signal skew on the device.

Abstract: A programmable logic array integrated circuit device includes a plurality of regions of programmable logic disposed on the device in a two-dimensional array of intersecting rows and columns. Interconnection conductors are associated with each row and column. The interconnection conductors associated with each row include some that extend continuously along the entire length of the row and some that extend continuously along only the left or right half of the row. To increase the flexibility with which the logic regions can be connected to the row and column conductors, adjacent regions are paired and circuitry is provided for allowing the outputs of each pair to be swapped for driving the row and column conductors. Registers in logic regions can still be used for other purposes when not being used to register the main combinatorial outputs of the logic regions. Many other enhanced features are also provided.

Abstract: A programmable logic array integrated circuit has a number of programmable logic modules which are grouped together in a plurality of logic array blocks (“LABs”). The LABs are arranged on the circuit in a two dimensional array. A conductor network is provided for interconnecting any logic module with any other logic module. In addition, adjacent or nearby logic modules are connectable to one another for such special purposes as providing a carry chain between logic modules and/or for connecting two or more modules together to provide more complex logic functions without having to make use of the general interconnection network. Another network of so-called fast or universal conductors is provided for distributing widely used logic signals such as clock and clear signals throughout the circuit. Multiplexers can be used in various ways to reduce the number of programmable interconnections required between signal conductors.

Abstract: A programmable logic integrated circuit device has several features which help it perform according to the PCI Special Interest Group's Peripheral Component Interface (“PCI”) signaling protocol. Some of the registers on the device are closely coupled for data input and output to data signal input/output pins of the device. The clock signal input terminals of at least these registers are also closely coupled to the clock signal input pin of the device. Programmable input delay is provided between the data signal input/output pins and the data input terminals of the above-mentioned registers to help compensate for clock signal skew on the device.

Abstract: A programmable logic array integrated circuit device includes a plurality of regions of programmable logic disposed on the device in a two-dimensional array of intersecting rows and columns. Interconnection conductors are associated with each row and column. The interconnection conductors associated with each row include some that extend continuously along the entire length of the row and some that extend continuously along only the left or right half of the row. To increase the flexibility with which the logic regions can be connected to the row and column conductors, adjacent regions are paired and circuitry is provided for allowing the outputs of each pair to be swapped for driving the row and column conductors. Registers in logic regions can still be used for other purposes when not being used to register the main combinatorial outputs of the logic regions. Many other enhanced features are also provided.

Abstract: A programmable logic array integrated circuit has a number of programmable logic modules which are grouped together in a plurality of logic array blocks (“LABs”). The LABs are arranged on the circuit in a two dimensional array. A conductor network is provided for interconnecting any logic module with any other logic module. In addition, adjacent or nearby logic modules are connectable to one another for such special purposes as providing a carry chain between logic modules and/or for connecting two or more modules together to provide more complex logic functions without having to make use of the general interconnection network. Another network of so-called fast or universal conductors is provided for distributing widely used logic signals such as clock and clear signals throughout the circuit. Multiplexers can be used in various ways to reduce the number of programmable interconnections required between signal conductors.

Abstract: A look-up-table-based programmable logic device is provided with memory circuitry which can be operated either as random access memory (“RAM”) or to perform product term (“p-term”) logic. Each individual row of the memory is separately addressable for writing data to the memory or, in RAM mode, for reading data from the memory. Alternatively, multiple rows of the memory are addressable in parallel to read p-terms from the memory. The memory circuitry of the invention is particularly useful as an addition to look-up-table-type programmable logic devices because the p-term capability of the memory circuitry provides an efficient way to perform wide fan-in logic functions which would otherwise require trees of multiple look-up tables.

Abstract: A programmable logic array integrated circuit device includes a plurality of regions of programmable logic disposed on the device in a two-dimensional array of intersecting rows and columns. Interconnection conductors are associated with each row and column. The interconnection conductors associated with each row include some that extend continuously along the entire length of the row and some that extend continuously along only the left or right half of the row. To increase the flexibility with which the logic regions can be connected to the row and column conductors, adjacent regions are paired and circuitry is provided for allowing the outputs of each pair to be swapped for driving the row and column conductors. Registers in logic regions can still be used for other purposes when not being used to register the main combinatorial outputs of the logic regions. Many other enhanced features are also provided.

Abstract: A technique is disclosed for performing an incremental recompile of an electronic design that has been previous compiled and then changed by a designer. This is accomplished by identifying a “sub-netlist” within the larger netlist of the changed design. The sub-netlist contains the sphere of influence of the designer's changes to the original design. During incremental recompile, only the sub-netlist is compiled; the remainder of the netlist is left as is from the previous compile. After the sub-netlist is synthesized, it is integrated back into the synthesized netlist from the previous compilation. The newly synthesized netlist for the changed design is mapped to logic cells which are then fit onto a target hardware device.

Abstract: In order to eliminate or substantially eliminate the need for circuitry to encode the address outputs of a content addressable memory which is equipped to perform sum-of-products logic, the memory contents are stored in such a way that the sum-of-products circuitry can encode the address outputs. A data word may be stored at several different locations in the memory, each of those locations being associated with a respective one of the positions or places in the encoded address that is to contain an affirmative response when the stored data word matches an applied data word. The sum-of-products circuitry of the memory is used to logically combine the outputs of the memory associated with each place of the encoded address in order to produce the appropriately encoded address output signal for that place.

Abstract: A progammable integrated circuit with a logic element including an input, an output and a logic function block wherein an input signal may be either passed form the input to the output bypassing the logic function block or the input signal may pass through the logic function block to provide a result to the output. Thus, a signal on the input may pass through the logic element without being logically altered or stored.

Abstract: A programmable logic array integrated circuit device includes a plurality of regions of programmable logic disposed on the device in a two-dimensional array of intersecting rows and columns. Interconnection conductors are associated with each row and column. The interconnection conductors associated with each row include some that extend continuously along the entire length of the row and some that extend continuously along only the left or right half of the row. To increase the flexibility with which the logic regions can be connected to the row and column conductors, adjacent regions are paired and circuitry is provided for allowing the outputs of each pair to be swapped for driving the row and column conductors. Registers in logic regions can still be used for other purposes when not being used to register the main combinatorial outputs of the logic regions. Many other enhanced features are also provided.

Abstract: A look-up-table-based programmable logic device is provided with memory circuitry which can be operated either as random access memory (“RAM”) or to perform product term (“p-term”) logic. Each individual row of the memory is separately addressable for writing data to the memory or, in RAM mode, for reading data from the memory. Alternatively, multiple rows of the memory are addressable in parallel to read p-terms from the memory. The memory circuitry of the invention is particularly useful as an addition to look-up-table-type programmable logic devices because the p-term capability of the memory circuitry provides an efficient way to perform wide fan-in logic functions which would otherwise require trees of multiple look-up tables.

Abstract: A disclosed method and mechanism provides for the use of hardware to perform the computations necessary for fitting an electronic design onto a substrate. This hardware design tool may be used in conjunction with a conventional software design tool which is reserved for performing other electronic design functions such as synthesis. In a disclosed example, the hardware tool performs the steps necessary to partition logic cells into logic blocks for use in a hierarchical electronic design. In this example, the hardware tool is provided as a product term device which temporarily stores information defining a given partitioning problem and then calculates the quality of the partition for every possible partition employing the constraints of the stored partitioning problem.

Abstract: A programmable logic array integrated circuit device has a plurality of regions of programmable logic disposed on the device in a two-dimensional array of intersecting rows and columns of regions. The output signals of several regions share a group of drivers for applying region output signals to interconnection conductors that convey signals between regions. This conserves driver resources and increases signal routing flexibility. Various approaches can be used for configuring the interconnection conductors to also conserve interconnection conductor resources. Logic regions may be used to directly drive specific input/output cells, thereby simplifying signal routing to the I/O cells and also possibly simplifying the structure of the I/O cells (e.g., by allowing certain I/O cell functions to be performed in the associated logic region).

Abstract: A look-up-table-based programmable logic device is provided with memory circuitry which can be operated either as random access memory (“RAM”) or to perform product term (“p-term”) logic. Each individual row of the memory is separately addressable for writing data to the memory or, in RAM mode, for reading data from the memory. Alternatively, multiple rows of the memory are addressable in parallel to read p-terms from the memory. The memory circuitry of the invention is particularly useful as an addition to look-up-table-type programmable logic devices because the p-term capability of the memory circuitry provides an efficient way to perform wide fan-in logic functions which would otherwise require trees of multiple look-up tables.

Abstract: A programmable logic array integrated circuit device includes regions of programmable logic, regions of memory, and a programmable network of interconnection conductors for selectively conveying signals to, from, and between the regions of logic and memory. The memory regions are usable as content addressable memory. Circuitry is provided for facilitating programming of the memory in content addressable mode.

Abstract: The invention relates to an integrated circuit that can be configured to operate as a content addressable memory. The integrated circuit includes a first functional block that stores at least one keyword dataword which is associated with a group of associated data words. The integrated circuit also includes a second functional block that stores the group of associated datawords. The second functional block is connected to the first functional block in such a way that if a request dataword received at the first functional block matches at least one keyword dataword stored therein, then an associated result dataword included in the group of associated data words stored in the second functional block is output by the second functional block. Typically, the integrated circuit chip is a complex programmable logic device architecture (CPLD).

Abstract: A method is provided in which a base design is generated in the form of one or more data files including assignment data. A variation design is created by adding at least one additional assignment associated with the variation design to the assignment data. The assignment data has an identifier that is associated with an entity defined within the base design, a first data field that can be used in making an assignment to the entity within the base design and a second data field for use in making the additional assignment to the entity within the variation design. The data files are compiled to generate a base output file and one or more variation output design files that can include one or more common result values. Comparison data is generated by comparing the common result values associated with the base design file and the variation design file. A design tool is provided for use with a computer system having a processor. The design tool includes a selector and a variation mechanism.

Abstract: A technique accurately calculates utilization information for an electronic design to help optimize the design. After synthesis of the complete design, information including number of combinatorial logic cells, maximum number of levels of combinatorial logic cells, number of registered logic cells, and number of latch logic cells for each line of source code is displayed. The information is in a source file text editor or in a graphic editor. The technique maps back from logic cells to technology-independent gates and back to lines of source code taking into account synthesized logic cells, and displays how many logic cells a line of source code is responsible for producing. For post-synthesis netlists having no synthesized logic cells, gates are grouped according to which logic cell they correspond. For netlists with synthesized logic cells, regions of logic cells within the netlist are first identified.