Register file backup queue

A register file backup system for use with a computer that processes instructions to generate results which thereby change the visual state of the computer, the computer having a register file with a plurality of addressable locations for storing data, the backup system adapted to return the visual state of the computer to a previous state if an instruction generates an exception, the backup system utilizing less overhead so as to provide easier register file backup than a comparable software or hardware device, the backup system comprising:

• a first-in, first-out result tag queue that sequentially stores in program order, address information corresponding to destination locations in the register file where instruction results are to be stored, said first-in, first-out result tag queue having first and second outputs for transferring said address information stored therein,
• (a) said first output coupled to the register file for transferring a first destination location to the register file, and
• (b) said second output for transferring a next destination location to the register file;
• a last-in, first-out backup queue, coupled to,
• (i) said second output of said first-in, first-out result tag queue, for receiving and storing said next destination location, and
• (ii) the register file, for receiving and backup storing data corresponding to contents of said next destination location in the register file before that destination location is changed;
• and
• third means for transferring said data from said last-in, first-out backup queue back to said next destination location in the register file after an instruction generates an exception.