Digital Electronics - The 8051 Microcontroller - Discussion

8051:

It doesn't have Z flag. Accumulator value is checked for Zero or non-Zero.

In this case, 0x01 is non-Zero and hence loop continues forever.

The answer is TRUE.

8085: Same instructions in 8085 works differently since it has Z flag which affects for Arithmetic or Logical Operations.

No flags are affected for a data transfer since it doesn't happen inside the ALU, and hence the value of Zero Flag depends on the previous Arithmetic or Logic instruction which is not known here, so let us assume Z flag = 1 on reset.

Right Answer in case of 8085: Unknown (FALSE may be the best answer if we consider the given TRUE/FALSE choices).

Agree @Anamika.

Zero flags won't be affected & hence JNZ condition will fail & loop should terminate. Since MOV A, #01 is a data transfer instruction & as we know data transfer instructions do not affect flags.

JNZ is jump if accumulator is not zero.

Here accumulator contain non-zero value, so it will be a continuous loop execution.

Here, JNZ is jumping on no-zero so A value is 1.

It's goto STAT.

How it is possible ? Because there is no continuous loop.

How is this possible?

Jmp instructions does not work after data transfer instruction. Then how will the loop run infinitely?

First instruction is a constant value with 01h so, it will never be zero hence it always jumps.

Jump to relative address, if A is not zero, since A is not zero so it jumps to STAT. Continues the loop.

JNZ means Jump if Non Zero.

jNZ instruction checks the Contents of Accumulator(A) register.
it's value is greater than zero every time... because it is not decrmenting. So, the loop will infinitely repeats...