Bus monitor with dual port memory for storing selectable trigger patterns

Abstract

A monitor for selectively detecting and recording conditions at selected points within a system includes a trigger memory for storing patterns of trigger signals, wherein each pattern of trigger signals corresponds to a selected condition to be detected on first points of the system. The trigger memory includes a first port having a read address input connected from the first points and a data output connected to trigger output logic for providing patterns of trigger signals corresponding to the conditions to be detected. Each pattern of trigger signals is stored in the trigger memory location whose address corresponds to a pattern of signals from the first points representing the corresponding condition to be detected. The trigger memory is a dual port memory having a second port with a write address input and a data input for receiving trigger patterns to be stored therein. The method for generating the trigger patterns includes generating a first trigger pattern map and, from the first map, a second trigger pattern map to be written into a trigger memory which includes a plurality of submemories, wherein each submemory stores a portion of the trigger patterns.