Definition 8.3.2: an instantaneous description (ID) of a RASP is a tuple of natural numbers , where i represents a value of the ic, x a value of the acc,and mk, 1ŠkŠN, represent the values of the each of the memory locations mk used by the RASP.The input values for a RASP are placed in the leading memory registers, m1, m2, m3, … prior to the start of execution, and the output value, if any, is the content of the accumulator (acc) when the program halts. Additional memory registers may be used for working storage without limit, and we assume that all these registers initially contain 0. We will adopt the convention that the last instruction of a RASP is always a HALT, and to halt at any other point in the program, a branch to the last instruction is executed.
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