RobEasy

Tuesday nights I have my microprocessors and industrial applications class. Just some background: I have been in this class for around five or six weeks. We are studying the Motorola 68HC11 microcomputer using a Heathkit trainer.

Tuesday we went over the architecture of the microprocessor and specifically delved into two apparently related addressing modes extended and indexed.

I understood and understand that the extended addressing mode requires three bytes, but the indexed addressing has caused me quite a lot of discomfort. I understand that there is an opcode and the offset address.

I know that you need to add the offset address to the address in the index register to find the operand address, but how the hell do you find the offset address in the first place?

Is it related to extended addressing where you have the higher order address and the lower address?

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