Texas Instruments Corporation

Brian Shore

Karl M Guttag

Derek Roskell

John V Schabowski

Kevin C McDonough

Thomas Preston

Marvin C Conrad

Jim A Carey

A digital synchronizer circuit including an input to receive an asynchronous level and a second input to receive an ansynchronous pulse. Both inputs are connected to the synchronizer input circuitry which will provide a level output for either type of input signal. This circuitry is connected to the remainder of the digital synchronizer which includes a latch connected to the level input and a level sensitive circuit connected to the output of the latch. The latch is constructed to provide a rapid transition between a logic '0' and '1'. In addition, the latch is periodically cleared. The level sensitive circuit provides a propagation barrier to any metastable state that may be present in the latch. However, the level sensitive circuit is also constructed for rapid transition from a logic '0' to a logic '1' when such a state occurs within the latch. An additional latch is connected in a further embodiment to provide additional reliability of the synchronizer circuit. The second latch is a two inverter latch with refresh for a three quarter of a machine cycle to allow any transient conditions within the latch to dampen out.

Synchronizer circuit with dual input

A digital processing system includes an external memory for the storage of program instructions for use with a separate processor that internally contains a memory for temporary storage, an arithmetic and logic means, a register set, control and timing circuitry, and two sets of data paths. The first set of data paths provide access to the external memory for transfer of instructions from the external memory to the processing unit. The second set of data paths provide for the internal routing of instructions data and addresses within the processor unit itself. The data structure for the first set of data paths is different than that for the second set of data paths, providing for an external data structure that is different than the internal data structure of the processor.

Single chip processor connected to an external memory chip

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Brian Shore