Chapter 2 - Data Manipulation - Section 2.2 - Machine Language - Questions & Exercises - Page 103: 6

The instruction 15AB requires that the CPU query the memory circuitry for the contents of the memory cell at address AB. This value, when obtained from memory, is then placed in register 5. The instruction 25AB does not require such a request for memory. Rather, the value AB is placed in register 5.

The instruction 15AB requires that the CPU query the memory circuitry for the contents of the memory cell at address AB. This value, when obtained from memory, is then placed in register 5. The instruction 25AB does not require such a request for memory. Rather, the value AB is placed in register 5.