Program Branching Instructions in MCS-51 - MCQs with Answers

Program Branching Instructions in MCS-51 - MCQs with Answers

Q1. Which among the category of program branching instructions allow 16 bit address to be specified & can jump anywhere within 64K block of program memory?

a. Long jumps (LJMP)
b. Short jumps (SJMP)
c. Absolute jumps (AJMP)
d. All of the above

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Q2. Consider the below mentioned statements . Which among them is /are approved to be incorrect in case of calling instructions of program branching?

A. Absolute Calls instructions specify 11-bit address and calling subroutine within 2K program memory block

B. Long call instructions specify 16-bit address and subroutine anywhere within 64K program memory block

C. Short call instructions specify 16-bit address and subroutine within 4K program memory block

D. All long call and short call instructions specify 11 bit address and the calling subroutine within 16K program memory block

Codes :
a. Only A
b. B & D
c. A & C
d. C & D

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Q3. Match the following instruction mnemonics with their description.

A. CJNE A,direct,rel ------- 1. Compare immediate to indirect and Jump if not equal
B. CJNE A,#data,rel ------- 2. Compare direct byte to accumulator and Jump if not equal
C. CJNE @R_i, #data,rel ------- 3. Compare immediate to register and Jump if not equal
D. CJNE R_n, # data rel ------- 4. Compare immediate to accumulator and Jump if not equal

Codes :

a. A-1, B-2, C-3, D-4
b. A-2, B-4, C-1, D-3
c. A-4, B-3, C-2, D-1
d. A-2, B-4, C-3, D-1

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Q4. What is the correct chronological order of the following steps involved in the LCALL operation?

1. Load the value of 16-bit destination address to program counter
2. Increment of the program counter by value '3'
3. Storage of the higher byte of program counter on the stack
4. Increment of the stack pointer by value'1'
5. Storage of the lower byte of program counter on the stack
6. Increment in the value of stack pointer

Codes :
a. 5, 3, 1, 6, 2, 4
b. 1, 3, 2, 5, 4, 6
c. 2, 4, 5, 6, 3, 1
d. 5, 3, 6, 2, 4, 1

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