1. In a coprocessing system comprising first and second data processors, a method for executing a selected single instruction in said first data processor, said execution of said instruction being contingent upon the status of a selected condition present in said second data processor, the method for executing the instruction comprising the steps of: (a) in a first portion of the execution of said instruction, said first processor writing to said second processor a request that said second processor evaluate said status of said selected condition and provide said first processor with an indication of whether, as a result of said evaluation, said selected condition was determined to have been satisfied; (b) in a second portion of the execution of said instruction, said first processor reading said indication provided by said second processor in response to said request; and (c) in a final portion of the execution of said instruction, said first processor selectively completing said execution of said instruction based upon said evaluation by said second processor as indicated by said indication.