Motorola Corporation

Oran Uzrad

Itai Katz

Doron Shoham

A history buffer system (12) for allowing the recovery of executed instructions comprises main history buffer (14) for storing addresses of issued instructions and at least one subsidiary history buffer (16, 22) associated with a predetermined type of data, such as fixed or floating point data. The subsidiary history buffer (16, 22) has a plurality of entries (Y, Z), each entry for storing a pointer to a register (18, 26) and the data stored in the register. The main history buffer (14) is arranged to store control data (fxtag, fptag) which associates the entries in a subsidiary history buffer with the appropriate issued instructions of the same data type stored in the main history buffer. The main history buffer (14) may comprise a storage entry for each issued instruction, each storage entry having a field for storing the address of an issued instruction, and at least one tag field (fxtag, fptag) corresponding to the at least one subsidiary history buffer (16, 22) for storing the control data.

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Sunnyvale, CA, United States of America

Oran Uzrad