Question

“DJNZ R0, label” is ________ byte instruction.

(a) 2

(b) 3

(c) 1

(d) Can’t be determined

The question was posed to me in a national level competition.

I would like to ask this question from Jump, Loop and Call Instructions topic in portion 8051 Microcontroller of Microcontroller

Answer 1

The correct choice is (a) 2

Explanation: DJNZ is 2-byte instruction. This means jump can be of -128 to +127 locations with respect to PC. Here -128 means upward or backward jump and +127 means downward or forward jump.