1. In a data processing system comprising a first data processing unit, a second data processing unit, and means for coupling said first and second data processing units for the bidirectional transfer of information therebetween, the information including instructions generated by the first data processing unit for controlling the operation of the second data processing unit by requesting said second data processing unit to perform predetermined functions, a response-control apparatus comprising: A. means, included in said second data processing unit, for receiving an instruction transferred from said first data processing unit by said coupling means; B. means, included in said second data processing unit, for decoding said received instruction into an operation corresponding to a said requested function to be performed by said second data processing unit; C. means, included in said second data processing unit, for generating a response to be transferred to said first data processing unit over said coupling means, said response for indicating whether said second data processing unit will perform said requested function; and D. means, included in said second data processing unit, for delaying said generation of said response by said generating means for a time period related to the particular operation decoded by said decoding means.