8051 Microcontroller set 2

Que: 11 DJNZ R0,label is how many bit instruction?
a. 2
b. 3
c. 1
d. Cant be determined
Que: 12 JZ, JNZ, DJNZ, JC, JNC instructions monitor the bits of which register ?
b. B
c. A
d. PSW
Que: 13 Calculate the jump code for again and here if code starts at 0000HMOV R1,#0MOV A,#0MOV R0,#25HAGAIN:ADD A,#0ECHJNC HEREHERE: INC R1DJNZ R0,AGAINMOV R0,AEND
a. F3,02
b. F9,01
c. E9,01
d. E3,02
Que: 14 When the call instruction is executed the top most element of stack comes out to be
a. the address where stack pointer starts
b. the address next to the call instruction
c. address of the call instruction
d. next address of the stack pointer
Que: 15 LCALL instruction takes
a. 2 bytes
b. 4 bytes
c. 3 bytes
d. 1 byte
Que: 16 Are PUSH and POP instructions are a type of CALL instructions?
a. yes
b. no
c. none of the mentioned
d. cant be determined
Que: 17 What is the time taken by one machine cycle if crystal frequency is 20MHz?
a. 1.085 micro seconds
b. 0.60 micro seconds
c. 0.75 micro seconds
d. 1 micro seconds
Que: 18 Find the number of times the following loop will be executedMOV R6,#200BACK:MOV R5,#100HERE:DJNZ R5, HEREDJNZ R6,BACKEND
a. 100
b. 200
c. 20000
d. 20000
Que: 19 What is the meaning of the instruction MOV A,05H ?
a. data 05H is stored in the accumulator
b. fifth bit of accumulator is set to one
c. address 05H is stored in the accumulator
d. none of the mentioned
Que: 20 Does the two instructions mean the same?1) BACK: DEC R0JZ BACK2) BACK: DJNZ RO, BACK
a. yes
b. no
c. cant be determined
d. yes and second one is preferred