What does m1 signal in Z80 describes? A. I/O operation status B. Memory refresh output C. Output pulse on instruction fetch cycle D. Interrupt request input

The correct answer is: C. Output pulse on instruction fetch cycle.

The M1 signal is a pulse that is generated by the Z80 microprocessor during the instruction fetch cycle. It is used to signal to external devices that an instruction is being fetched from memory.

The other options are incorrect because:

• Option A is incorrect because the I/O operation status is not signaled by the M1 signal. The I/O operation status is signaled by the I/O request signal (IORQ).
• Option B is incorrect because the memory refresh output is not signaled by the M1 signal. The memory refresh output is signaled by the memory refresh control signal (MEMR).
• Option D is incorrect because the interrupt request input is not signaled by the M1 signal. The interrupt request input is signaled by the interrupt request signal (INTR).