Abstract: An integrated circuit with programmable transistors is programmed via a state machine on the integrated circuit. For example, the integrated circuit may be a programmable logic device, and the state machine may be a JTAG state machine. Each integrated circuit may have on it a register containing data indicating how long a particular programming operation should continue in order to be successful for that circuit. External programming control apparatus first reads that data and then at least partly bases the timing of programming instructions applied to the integrated circuit on that data. The integrated circuit may have an on-board programming voltage generating circuit which is turned on only by appropriate instructions from the external programming control apparatus. The external programming control apparatus controls the sequence and timing of all programming operations via the state machine port of the integrated circuit.

Abstract: An diagnostic interface system for a programmable logic system is disclosed. The diagnostic interface system provides an efficient and flexible mechanism for accessing internal nodes of programmable logic devices (PLDs) to facilitate debugging and troubleshooting of the programmable logic system. The interface system includes a diagnostic data bus connecting external I/O pins to various diagnostic data and address registers that connect to the internal circuitry of a PLD. A diagnostics controller controls the various diagnostic resources in response to user supplied control data.

Abstract: A system and method for programming elements in an integrated circuit. The system allows for selection of an internal voltage supply and an external supply. Provision is also possible for improved testing techniques.

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: A programmable logic device (PLD) that provides the capability to observe and control the logic state of buried internal nodes is disclosed. The PLD provides shadow storage units for internal nodes such as logic element registers, memory cells, and I/O registers. A sample/load data path includes bidirectional data buses and shift register that facilitate the sampling of internal nodes for observing their logic states, and loading of internal nodes for controlling their logic states.

Abstract: An integrated circuit with programmable transistors is programmed via a state machine on the integrated circuit. For example, the integrated circuit may be a programmable logic device, and the state machine may be a JTAG state machine. Each integrated circuit may have on it a register containing data indicating how long a particular programming operation should continue in order to be successful for that circuit. External programming control apparatus first reads that data and then at least partly bases the timing of programming instructions applied to the integrated circuit on that data. The integrated circuit may have an on-board programming voltage generating circuit which is turned on only by appropriate instructions from the external programming control apparatus. The external programming control apparatus controls the sequence and timing of all programming operations via the state machine port of the integrated circuit.

Abstract: A programmable logic device is provided that contains a plurality of logic array blocks arranged in rows and columns. The logic array blocks are interconnected with horizontal conductors in each row and vertical conductors in each column. The logic array blocks and the interconnections between conductors are configured using programmable logic. Some of the programmable logic is used to selectively connect logic array block input terminals to the horizontal conductors. Additional logic in each column is used to selectively connect the horizontal conductors to either logic array block output terminals from the same column or logic array block output terminals from an adjacent column. The additional logic prevents certain interconnection pathways from being blocked and increases the overall flexibility of the interconnection scheme of the programmable logic device, thereby improving device performance.

Abstract: A programmable logic device is provided that has a two-dimensional array of logic array blocks. The logic array blocks, which contain advanced macrocells, contain programmable input arrays based on pterm logic and are two-dimensionally interconnected with global horizontal and vertical conductors. The logic array blocks and the connections between conductors are configured using programmable multiplexers and demultiplexers. Redundant conductive pathways are provided so that the programmable logic device may be efficiently programmed to perform a variety of logic functions. Furthermore, logic is provided with each logic array block that allows the global horizontal and vertical conductors to be interconnected without directly involving the logic in the logic array block, which therefore can be used to provide greater logical functionality.

Abstract: A programmable logic device is provided that has redundant circuitry. When a portion of the programmable logic device circuitry is found to be defective, the redundant circuitry is switched into use in place of the defective circuitry by programming appropriate portions of the circuitry of the programmable logic device. The programmable logic device is arranged in rows and columns of programmable logic containing logic array blocks, which a user selectively configures by loading programming data into vertical and horizontal programming blocks. Programming blocks are used to program the logic array blocks and various associated logic circuitry. When the redundant circuitry is switched into place, the programming data is redirected to the appropriate programming blocks, so that the device functions identically, regardless of whether or not the redundant circuitry is used.

Abstract: An improved macrocell is provided for summing product term inputs to complete a sum of products. Some or all of a macrocell's product terms can be allocated to another macrocell. The macrocell OR function remains available to sum product term inputs, even when other product term inputs in the same macrocell are allocated elsewhere. Macrocells can also by daisy-chained bidirectionally, so that the delay associated with allocating product terms between multiple macrocells can be reduced.

Abstract: A circuit having a data path with a programmable clock-to-output delay time (t.sub.co). The circuit includes a master-slave flip-flop and selection/predriver logic circuitry whereby two select inputs can program the circuit into one of three different modes of operation. In a data-in mode, the input data is directly connected to the output driver, bypassing the flip-flop. In a fast mode, the circuit t.sub.co is reduced such that a higher frequency clock may be used. For low noise operation, the fast mode may be turned off to put the circuit in the regular mode, allowing the circuit to run at lower clock frequencies.

Abstract: An input/output cell for interconnecting an I/O pad with internal circuitry in a programmable logic device provides clocked and unclocked inputs through an internal bus to selected logic array blocks. The input/output cell further includes a fast input line in which the I/O pad is directly connected with a selected logic array block without travelling through the latch circuitry of the I/O cell and the internal bus of the programmable logic device.