The fault can be easily diagnosed in the micro-program control unit using…
2019
The fault can be easily diagnosed in the micro-program control unit using diagnostic tools by maintaining the contents of
- A.
flags and counters
- B.
registers and counters
- C.
flags and registers
- D.
flags, registers and counters
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Correct answer: D
Answer: maintain the contents of flags, registers and counters.
Why this is needed:
Flags: Show status and condition bits (for example zero, carry, overflow) that influence control decisions. Inspecting flags helps detect incorrect conditional behavior.
Registers: Contain intermediate data, microinstruction fields, and control signals. Viewing register contents reveals corrupted data or stuck bits in data paths.
Counters: Include the microprogram counter and sequence counters that show the execution order and timing. Preserving counter values lets you trace the exact microinstruction sequence where the fault appears.
Practical diagnostic steps:
Capture snapshots of registers and counters at the moment the fault occurs.
Examine flags for unexpected status bits that might change control flow.
Compare the observed microinstruction sequence (from counters) and register contents with the expected behavior to localize the fault to a control decision, data path, or sequencing logic.
Therefore, maintaining the contents of flags, registers and counters gives a complete view (status, data, and control flow) needed to reproduce and isolate faults in the micro-program control unit.
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