29. Direct addressing is immediate addressing deferred. Indirect addressing is direct addressing deferred. You can carry this concept one level further with double indirect addressing, which is indirect addressing deferred. Implement a new instruction in place of NOP0 with mnemonic STWADI, which stands for store word accumulator double indirect. It should store the accumulator using double indirect addressing. None of the status flags are affected. NOP0 is a unary instruction as far as the assembler and CPU are concerned, but your program must implement it as a nonunary instruction. You will need to increment the saved PC to skip over the operand specifier. Use the test program provided in the Pep/9 app to test the features of the new instruction.