Question 1 |
The content of the registers are R_{1} = 25H, R_{2} = 30H and R_{3} = 40H. The following machine instructions are executed.
\text{PUSH } \{R_{1}\}
\text{PUSH } \{R_{2}\}
\text{PUSH } \{R_{3}\}
\text{POP } \{R_{1}\}
\text{POP } \{R_{2}\}
\text{POP } \{R_{3}\}
After execution, the content of registers R_{1},\:R_{2},\:R_{3} are
\text{PUSH } \{R_{1}\}
\text{PUSH } \{R_{2}\}
\text{PUSH } \{R_{3}\}
\text{POP } \{R_{1}\}
\text{POP } \{R_{2}\}
\text{POP } \{R_{3}\}
After execution, the content of registers R_{1},\:R_{2},\:R_{3} are
R_{1}=40H,\:R_{2}=30H,\:R_{3}=25H | |
R_{1}=25H,\:R_{2}=30H,\:R_{3}=40H | |
R_{1}=30H,\:R_{2}=40H,\:R_{3}=25H | |
R_{1}=40H,\:R_{2}=25H,\:R_{3}=30H |
Question 1 Explanation:
For PUSH SP is decremented and for POP SP is incremented.
\begin{aligned} \therefore \qquad [\mathrm{R} 1]&=40 \\ [\mathrm{R} 2]&=30 \\ [\mathrm{R} 3]&=25 \end{aligned}
\begin{aligned} \therefore \qquad [\mathrm{R} 1]&=40 \\ [\mathrm{R} 2]&=30 \\ [\mathrm{R} 3]&=25 \end{aligned}
Question 2 |
In an 8085 microprocessor, the number of address lines required to access a 16 K byte
memory bank is __________.
16 | |
14 | |
12 | |
15 |
Question 2 Explanation:
\begin{aligned}2^{n}&=N \\
n & \rightarrow \text{ Number of Address Lines} \\ N & \rightarrow \text{ Number of Memory Locations} \\ 2^{n}&=16 KB \\ &=2^{4} (2^{10}) \\ &=2^{14}\\ n&=14\end{aligned}
Question 3 |
The following FIVE instructions were executed on an 8085 microprocessor.
MVI A, 33H
MVI B, 78H
ADD B
CMA
ANI 32H
The Accumulator value immediately after the execution of the fifth instruction is
MVI A, 33H
MVI B, 78H
ADD B
CMA
ANI 32H
The Accumulator value immediately after the execution of the fifth instruction is
00H | |
10H | |
11H | |
32H |
Question 3 Explanation:
\begin{aligned} \text { MVI } A, 33 H &: (A)=33 H \\ \text { MVI B, } 78 \text { H } &: \text { (B) }=78 \mathrm{H} \\ \text { ADD } \mathrm{B} &: (\mathrm{A}) \leftarrow(\mathrm{A})+(\mathrm{B})=33 \mathrm{H} \\ +78 \mathrm{H}=\mathrm{AB} &\text { H } \Rightarrow (\mathrm{A})=\mathrm{AB} \mathrm{H} \\ &\text { (A) }=10101011\\ CMA&:\text{Complement}\\ \text { Accumulator } &\Rightarrow(A) =01010100 \\ \text { ANI } 32 \mathrm{H} &:\text { (A) } \leftarrow(\text { A) AND } 32 \mathrm{H} \\ &\quad 01010100\\ &\quad 00110010\\ &\quad 10010000 \Rightarrow(A)=10 H \end{aligned}
Question 4 |
The clock frequency of an 8085 microprocessor is 5 MHz. If the time required to execute an instruction is 1.4 \mu s, then the number of T-states needed for executing the instruction is
1 | |
6 | |
7 | |
8 |
Question 4 Explanation:
Given than,
f_{\mathrm{CLK}}=5 \mathrm{MHz}
Execution time =1.4 \mu \mathrm{s}
Execution time =n(T-\text { state })
n= number of T-states required to execute the instruction
T- state (or) T_{\mathrm{CLK}}=\frac{1}{f_{\mathrm{CLK}}}=0.2 \mu \mathrm{s}
So, \quad n=\frac{1.4 \mu \mathrm{s}}{T_{\mathrm{CLK}}}=\frac{1.4}{0.2}=7
f_{\mathrm{CLK}}=5 \mathrm{MHz}
Execution time =1.4 \mu \mathrm{s}
Execution time =n(T-\text { state })
n= number of T-states required to execute the instruction
T- state (or) T_{\mathrm{CLK}}=\frac{1}{f_{\mathrm{CLK}}}=0.2 \mu \mathrm{s}
So, \quad n=\frac{1.4 \mu \mathrm{s}}{T_{\mathrm{CLK}}}=\frac{1.4}{0.2}=7
Question 5 |
In an 8085 microprocessor, the contents of the accumulator and the carry flag are A7 (in hex) and 0, respectively. If the instruction RLC is executed, then the contents of the accumulator (in hex) and the carry flag, respectively, will be
4E and 0 | |
4E and 1 | |
4F and 0 | |
4F and 1 |
Question 5 Explanation:
RLC: Rotate accumulator left by 1 bit without carry
Before RLC operation:
\begin{aligned} A &=A 7 H=(10100111)_{2} \\ C Y &=0 \end{aligned}
After RLC operation:
\begin{aligned} A &=(01001111)_{2}=4 \mathrm{FH} \\ \mathrm{CY} &=1 \end{aligned}
Before RLC operation:
\begin{aligned} A &=A 7 H=(10100111)_{2} \\ C Y &=0 \end{aligned}
After RLC operation:
\begin{aligned} A &=(01001111)_{2}=4 \mathrm{FH} \\ \mathrm{CY} &=1 \end{aligned}
There are 5 questions to complete.