1995-03-13
1996-12-24
Beausoliel, Jr., Robert W.
39518502, G06F 1100
Patent
active
055881130
ABSTRACT:
A register file backup system for use with a computer which processes instructions to generate results which thereby change the visual state of the computer. The computer has a register file with a plurality of addressable locations for storing data. The backup system is adapted to return the visual state of the computer to a previous state if an instruction generates an exception. The backup system utilizes less overhead so as to provide easier register file backup than a comparable software or hardware device. The backup system comprises in a first-in-first out (FIFO) queue for sequentially storing in program order, address information corresponding to destination locations in the register file where instruction results are to be stored. The FIFO queue has first and second outputs for transferring the address information stored therein: the first output being coupled to the register file for transferring a first portion of the address information to the register file, and the second output is used for transferring a second portion of address information for backup storage of the register file contents. The backup system also has a last-in-first out (LIFO) queue coupled to (1) the second output of the first means, for receiving and storing the second portion of the address information, and (2) the register file, for receiving and backup storing further information corresponding to the contents of one or more destination locations in the register file before that destination location is changed according to second portion of the address information. Additional circuitry is used for transferring the further information from the last-in-first out (LIFO) queue back to the register file locations according to the second portion of the address information stored in the last-in-first out (LIFO) queue after an instruction generates an exception.
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Beausoliel, Jr. Robert W.
Palys Joseph E.
Seiko Epson Corporation
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