4.11 EXTENDING OUR INSTRUCTION SET
Even though MARIE’s instruction set is sufficient to write any program we wish, there are a few instructions we can add to make programming much simpler. We have 4 bits allocated to the opcode, which implies that we can have 16 unique instructions, and we are using only 9 of them. Surely, we can make many programming tasks much easier by adding a few well-chosen instructions to our instruction set. Our new instructions are summarized in Table 4.6.
TABLE 4.6 MARIE’s Extended Instruction Set
The JnS (jump-and-store) instruction allows us to store a pointer to a return instruction and then proceeds to ...
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