Motorola Corporation

John K Eitrheim

Ashok H Someshwar

Bernard J Pappert

Ernest A Carter

Dorothy M Wood

Improved access to programmable logic arrays is provided by continuously asserting and negating a latch inputs control signal, continuously asserting and negating a control signal which discharges a first logic section of the array to provide frequent, current inputs to a second logic section of the PLA and discharging the second section of the PLA only upon receipt of an access request. In the case of asynchronous access, it is also necessary to generate a synchronized data strobe from the unsynchronized one and to generate an acknowledge signal to indicate the presence of valid output data. The disclosed method and apparatus provide access which has a short access time and which also provides outputs which reflect relatively current states of the inputs thereto.

Method and apparatus for access to a PLA

A two stage synchronizer circuit for synchronizing an asynchronous input signal with a local clock signal includes a reference inverter for generating a reference signal, a first sense amplifier for amplifying the difference between the reference signal and the asynchronous input signal, buffer inverters coupled to the output on the sense amplifier, a second sense amplifier coupled to the output of the buffer inverters, and an output inverter for delivering the desired synchronized signal. The reference inverter and the first and second buffer inverters have the same switch point so as to substantially reduce the probability of the generation of a meta-stable output. Furthermore, the first and second sense amplifiers and output inverter also have the same switch point as the reference inverter.

Two state synchronizer

A read-only-memory (ROM) having a plurality of enhancement and depletion transistors selectively arranged in an array with the gates of the transistors in each row connected in common to form word lines, and the current paths of the transistors in each column connected in series to form bit lines. The word lines are precharged and then allowed to float. The bit lines are then precharged, bootstrapping the word lines above the precharge level. A selected one of the word lines is thereafter discharged before one end of each of the bit lines is connected to ground. A selected bit line will either remain precharged or be discharged depending upon the type of transistor at the intersection of the selected word and bit lines.

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Cedar Park, TX, United States of America

John K Eitrheim