1. A method for storing the state of a computer system for recovery at a later time, the computer system including a target processor programmed with a target program having a plurality of instruction blocks, each of the blocks having at least one variable associated therewith and a memory having first and second levels, each of the levels having a plurality of locations, the first level of memory being connected to the target processor, the method comprising the steps of: storing a first value of the at least one variable in a first location of the first level of memory; generating a first signal indicating the beginning of an instruction block; transferring, without interrupting execution of the instruction block, the first value of the at least one variable to a corresponding second location in the second level of memory from the first location in the first level based on the first signal, the first and second locations of the first and second levels, of memory, respectively, defining a push down stack having a push down mode and a locked mode, the first value being transferred to the second location in the push down mode, the value of the at least one variable in the second location of the second level remaining unchanged in the locked mode during the execution of the instruction block, the value of the at least one variable being allowed to change in the first location of the first level during execution of the instruction block and wherein the first value of the at least one variable contained in the second location of the second level is utilized for recovering the state of the computer system to that state at the beginning of the instruction block; and storing a second value of the at least one variable in the first location of the first level of memory, the second value being different from the first value whereby the second level of memory reflects the state of the computer system at the beginning of the instruction block; whereby the second level of memory reflects the state of the computer system at the beginning of the instruction block.