Consider a hypothetical computer with an instruction set of only two n-bit instructions. The first bit specifies the opcode, and the remaining bits specify one of the 2n-1 n-bit words of main memory. The two instructions are as follows:
SUBS X Subtract the contents of location X from the accumulator, and store the result in location X and the accumulator.
JUMP X Place address X in the program counter.
A word in main memory may contain either an instruction or a binary number in twos complement notation. Demonstrate that this instruction repertoire is reasonably complete by specifying how the following operations can be programmed:
a. Data transfer: Location X to accumulator, accumulator to location X
b. Addition: Add contents of location X to accumulator