Abstract: A programmable logic device having a relatively small number of programmable product terms ("P-terms") feeding each fixed combinatorial logic device, and additional "expander" programmable P-terms which do not directly feed a fixed device. Relatively simple logic functions can be performed by suitably programming the P-terms feeding the fixed devices. More complex logic functions can be performed by suitably programming the required number of expander P-terms, and then combining the outputs of those P-terms by means of another P-term. In order to conserve word lines in the programmable array, multiplexers allow selection of whether expander outputs or external inputs will be applied to certain word lines.

Abstract: A programmable macrocell 28 for use in an integrated circuit device including an electronic circuit 32 responsive to control signals and operative to perform particular operations selected by the control signals on input data signals and to develop commensurate output signals, and one or more architecture control circuits 30 each including a programmable EPROM device 34 which when programmed generates a logic signal of a first state and when unprogrammed generates a logic signal of a second state, a read and write control circuit 36 responsive to input program data signals and a corresponding address signal and operative to program the EPROM device 34 by applying a programming potential thereto, and a sensing circuit 38 for sensing the programmed or unprogrammed status of the EPROM device 34 and for developing a commensurate control signal for input to the electronic circuit 32.