A digital data processing system, comprising: a memory defining a real address space; a processor for executing processes embodied as instructions storable in said memory, at least some of said processes generating memory references in a respective effective address space different from said real address space; a coprocessor for performing operations, each operation on behalf of a first process executing in said processor, said coprocessor accessing data operands in said memory using real addresses in said real address space; the processor further operable for invoking said coprocessor to perform a first operation on behalf of the first process, said first process operable for generating memory references in a first effective address space; means for generating a first effective address in said first effective address space; means for generating a second effective address in said first effective address space of a first data operand for performing said first operation; means for translating said first effective address to a first real address in said real address space; means for translating said second effective address to a second real address in said real address space; characterized in that it further comprises: means for storing said second real address in a block of memory referenced by said first effective address; and means for transmitting a request to perform said first operation to said coprocessor, said request containing said first real address, said coprocessor operable for using said first real address to access at least one data operand for performing said first operation, by using said first real address to access said second real address in said block of memory, and for using said second real address to access said first data operand. a memory defining a real address space; a processor for executing processes embodied as instructions storable in said memory, at least some of said processes generating memory references in a respective effective address space different from said real address space; a coprocessor for performing operations, each operation on behalf of a first process executing in said processor, said coprocessor accessing data operands in said memory using real addresses in said real address space; the processor further operable for invoking said coprocessor to perform a first operation on behalf of the first process, said first process operable for generating memory references in a first effective address space; means for generating a first effective address in said first effective address space; means for generating a second effective address in said first effective address space of a first data operand for performing said first operation; means for translating said first effective address to a first real address in said real address space; means for translating said second effective address to a second real address in said real address space; characterized in that it further comprises: means for storing said second real address in a block of memory referenced by said first effective address; and means for transmitting a request to perform said first operation to said coprocessor, said request containing said first real address, said coprocessor operable for using said first real address to access at least one data operand for performing said first operation, by using said first real address to access said second real address in said block of memory, and for using said second real address to access said first data operand. means for storing said second real address in a block of memory referenced by said first effective address; and means for transmitting a request to perform said first operation to said coprocessor, said request containing said first real address, said coprocessor operable for using said first real address to access at least one data operand for performing said first operation, by using said first real address to access said second real address in said block of memory, and for using said second real address to access said first data operand.