Abstract: A mask programmable logic array (PLA) for producing a particular digital output given a certain digital input. The input signals to the PLA first pass through a series of AND gates resulting in a predetermined number of product terms being formed. The product signals then pass through a set of OR gates to become the final output signals. In the subject invention, the AND gates and OR gates are implemented through the use of NOR-NOR logic. A first set of NOR gates is implemented in an array to receive input signals and to produce product terms. A second and third set of NOR gates form two arrays. These two arrays are then located on either side of the first array to receive selected product signals in order to produce final output signals. In effect the OR portion of the PLA has been split into two arrays.

Abstract: The chip topography of an MOS microprocessor chip. The chip architecture includes an internal data bus and an internal address bus. Input/output circuitry is located along the top edge of the chip and is coupled to the data bus. Output circuitry is located along the bottom edge and coupled to the address bus. A program storage area which includes a ROM is located in the lower left hand corner of the chip. The ROM contains instruction words for defining the operation of the microprocessor. A data storage area which includes a RAM is located in the upper left hand corner of the chip and is coupled to the data bus. An ALU area is located to the right of the data storage area and is coupled to the data bus for performing arithmetic and logic operations on data. A condition decode ROM located in the approximate center of the chip is coupled to the data bus and is used for decoding a condition field of an instruction word received from the ROM.

Abstract: For use in a microprocessor on a single semiconductor chip, circuitry responsive to a timing signal and a data signal for discharging a precharged data line to correspond to the data to be transmitted on the data line. First and second enhancement-type field effect devices are connected in series with the drain of the first device being connected to the data line and the source of the second device being connected to a source voltage. The gate of one of the field effect devices provides an input for the timing signal. The gate of the remaining field effect device provides an input for the data signal. A depletion-type field effect device has its source and gate coupled to the series connection point and its drain connected to a drain voltage source. The depletion-type field effect device prevents a charge redistribution from the data line to the series field effect devices when these devices are not discharging the line.