So far you have verified that the microprocessor has performed the correct reset vector search. The next thing you must verify is whether the microprocessor addresses the correct location in ROM that it was instructed to address in state 4 and whether the data is correct in this ROM location. From the listing you see that the address in state 4 is 008048, which is correct, but the instruction found in this location is 2E7C, which is not correct. You have found your problem: incorrect data stored in ROM for the microprocessor’s first instruction.
+0000 000000 0000 (high word of stack pointer location)
+0001 000002 04FC (low word of stack pointer location)
+0002 000004 0000 (high word of instruction fetch location)
+0003 000006 8048 (low word of instruction fetch location)
+0004 008048 2E7C (first microprocessor instruction)
Incorrect Data
Figure
HP 16510B | Using the State Analyzer |
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