Electrical Engineering Questions And Answers

1⟩ Given the following Verilog code, what value of "a" is displayed?

Given the following Verilog code, what value of "a" is displayed?

always @(clk) begin

a = 0;

a <= 1;

$display(a);

end

This is a tricky one! Verilog scheduling semantics basically imply a four-level deep queue for the current simulation time:

1: Active Events (blocking statements)

2: Inactive Events (#0 delays, etc)

3: Non-Blocking Assign Updates (non-blocking statements)

4: Monitor Events ($display, $monitor, etc).

Since the "a = 0" is an active event, it is scheduled into the 1st "queue". The "a <= 1" is a non-blocking event, so it's placed into the 3rd queue. Finally, the display statement is placed into the 4th queue.

Only events in the active queue are completed this sim cycle, so the "a = 0" happens, and then the display shows a = 0. If we were to look at the value of a in the next sim cycle, it would show 1.

Is this answer helpful? 0 Yes | 0 No

Answer This Question

207 views

2⟩ What is the difference between c = foo ? a b; and if (foo) c = a; else c = b;

The ? merges answers if the condition is "x", so for instance if foo = 1'bx, a = 'b10, and b = 'b11, you'd get c = 'b1x.

On the other hand, if treats Xs or Zs as FALSE, so you'd always get c = b.

Is this answer helpful? 0 Yes | 0 No

Answer This Question

186 views

3⟩ What is the difference between a Verilog task and a Verilog function?

The following rules distinguish tasks from functions:

A function shall execute in one simulation time unit;

a task can contain time-controlling statements.

A function cannot enable a task;

a task can enable other tasks or functions.

A function shall have at least one input type argument and shall not have an output or inout type argument;

a task can have zero or more arguments of any type.

A function shall return a single value; a task shall not return a value.

Is this answer helpful? 0 Yes | 0 No

Answer This Question

219 views

4⟩ What is the difference between the following two lines of Verilog code?

What is the difference between the following two lines of Verilog code?

#5 a = b;

a = #5 b;

#5 a = b; Wait five time units before doing the action for "a = b;".

The value assigned to a will be the value of b 5 time units hence.

a = #5 b; The value of b is calculated and stored in an internal temp register.

After five time units, assign this stored value to a.

Is this answer helpful? 0 Yes | 0 No

Answer This Question

195 views

5⟩ Using the given, draw the waveforms for the following versions of a?

Using the given, draw the waveforms for the following versions of a (each version is separate, i.e. not in the same run):

reg clk;

reg a;

always #10 clk = ~clk;

(1) always @(clk) a = #5 clk;

(2) always @(clk) a = #10 clk;

(3) always @(clk) a = #15 clk;

Now, change a to wire, and draw for:

(4) assign #5 a = clk;

(5) assign #10 a = clk;

(6) assign #15 a = clk;

Is this answer helpful? 0 Yes | 0 No

Answer This Question

223 views

6⟩ Given the following snipet of Verilog code draw out the waveforms for clk?

Given the following snipet of Verilog code, draw out the waveforms for clk and a

always @(clk) begin

a = 0;

#5 a = 1;

end

10 30 50 70 90 110 130

___ ___ ___ ___ ___ ___ ___

clk ___| |___| |___| |___| |___| |___| |___| |___

a ___________________________________________________________

This obviously is not what we wanted, so to get closer, you could use

"always @ (posedge clk)" instead, and you'd get

10 30 50 70 90 110 130

___ ___ ___ ___ ___ ___ ___

clk ___| |___| |___| |___| |___| |___| |___| |___

___ ___

a _______________________| |___________________| |_______

Is this answer helpful? 0 Yes | 0 No

Answer This Question

200 views

7⟩ Explain the differences between "Direct Mapped", "Fully Associative", and "Set Associative" caches

If each block has only one place it can appear in the cache, the cache is said to be direct mapped. The mapping is usually (block-frame address) modulo (number of blocks in cache).

If a block can be placed anywhere in the cache, the cache is said to be fully associative.

If a block can be placed in a restricted set of places in the cache, the cache is said to be set associative. A set is a group of two or more blocks in the cache. A block is first mapped onto a set, and then the block can be placed anywhere within the set. The set is usually chosen by bit selection; that is, (block-frame address) modulo (number of sets in cache). If there are n blocks in a set, the cache placement is called n-way set associative.

Is this answer helpful? 0 Yes | 0 No

Answer This Question

229 views

8⟩ Given the following FIFO and rules, how deep does the FIFO need to be to prevent underflowing or overflowing?

Given the following FIFO and rules, how deep does the FIFO need to be to prevent underflowing or overflowing?

RULES:

1) frequency(clk_A) = frequency(clk_B) / 4

2) period(en_B) = period(clk_A) * 100

3) duty_cycle(en_B) = 25%

Assume clk_B = 100MHz (10ns)

From (1), clk_A = 25MHz (40ns)

From (2), period(en_B) = 40ns * 400 = 4000ns, but we only output for 1000ns, due to (3), so 3000ns of the enable we are doing no output work.

Therefore, FIFO size = 3000ns/40ns = 75 entries.

Is this answer helpful? 0 Yes | 0 No

Answer This Question

214 views

9⟩ Write a function to determine whether a string is a palindrome (same forward as reverse, such as "radar" or "mom")

/* BEGIN C SNIPET */

#include

void is_palindrome ( char *in_str ) {

char *tmp_str;

int i, length;

length = strlen ( *in_str );

for ( i = 0; i < length; i++ ) {

*tmp_str[length-i-1] = *in_str[i];

}

if ( 0 == strcmp ( *tmp_str, *in_str ) ) printf ("String is a palindrome");

else printf ("String is not a palindrome");

}

/* END C SNIPET */

Is this answer helpful? 0 Yes | 0 No

Answer This Question

197 views

10⟩ Write the code for finding the factorial of a passed integer. Use a recursive subroutine?

// BEGIN PERL SNIPET

sub factorial {

my $y = shift;

if ( $y > 1 ) {

return $y * &factorial( $y - 1 );

} else {

return 1;

}

// END PERL SNIPET

Is this answer helpful? 0 Yes | 0 No

Answer This Question

229 views

11⟩ Draw the state diagram for a circuit that outputs?

Draw the state diagram for a circuit that outputs a "1" if the aggregate serial binary input is divisible by 5. For instance, if the input stream is 1, 0, 1, we output a "1" (since 101 is 5). If we then get a "0", the aggregate total is 10, so we output another "1" (and so on).

We don't need to keep track of the entire string of numbers - if something is divisible by 5, it doesn't matter if it's 250 or 0, so we can just reset to 0. So we really only need to keep track of "0" through "4".

Is this answer helpful? 0 Yes | 0 No

Answer This Question

199 views

12⟩ Write a function to output a diamond shape according to the given (odd) input?

Examples: Input is 5 Input is 7

* *

*** ***

***** *****

*** *******

* *****

***

*

### BEGIN PERL SNIPET ###

for ($i = 1; $i <= (($input * 2) - 1); $i += 2) {

if ($i <= $input) {

$stars = $i;

$spaces = ($input - $stars) / 2;

while ($spaces--) { print " "; }

while ($stars--) { print "*"; }

} else {

$spaces = ($i - $input) / 2;

$stars = $input - ($spaces * 2);

while ($spaces--) { print " "; }

while ($stars--) { print "*"; }

}

print "n";

}

### END PERL SNIPET ###

Is this answer helpful? 0 Yes | 0 No

Answer This Question

188 views

13⟩ Design a four-input NAND gate using only two-input NAND gates

Basically, you can tie the inputs of a NAND gate together to get an inverter, so...

Is this answer helpful? 0 Yes | 0 No

Answer This Question

226 views

14⟩ In C, explain the difference between the & operator and the * operator?

& is the address operator, and it creates pointer values.

* is the indirection operator, and it preferences pointers to access the object pointed to.

Example:

In the following example, the pointer ip is assigned the address of variable i (&i). After that assignment, the expression *ip refers to the same object denoted by i:

int i, j, *ip;

ip = &i;

i = 22;

j = *ip; /* j now has the value 22 */

*ip = 17; /* i now has the value 17 */

Is this answer helpful? 0 Yes | 0 No

Answer This Question

190 views

15⟩ Write the code to sort an array of integers?

/* BEGIN C SNIPET */

void bubblesort (int x[], int lim) {

int i, j, temp;

for (i = 0; i < lim; i++) {

for (j = 0; j < lim-1-i; j++) {

if (x[j] > x[j+1]) {

temp = x[j];

x[j] = x[j+1];

x[j+1] = temp;

} /* end if */

} /* end for j */

} /* end for i */

} /* end bubblesort */

/* END C SNIPET */

Some optimizations that can be made are that a single-element array does not need to be sorted; therefore, the "for i" loop only needs to go from 0 to lim-1. Next, if at some point during the iterations, we go through the entire array WITHOUT performing a swap, the complete array has been sorted, and we do not need to continue. We can watch for this by adding a variable to keep track of whether we have performed a swap on this iteration.

Is this answer helpful? 0 Yes | 0 No

Answer This Question

178 views

16⟩ What is the difference between running the following snipet of code on Verilog vs Vera?

What is the difference between running the following snipet of code on Verilog vs Vera?

fork {

task_one();

#10;

task_one();

}

task task_one() {

cnt = 0;

for (i = 0; i < 50; i++) {

cnt++;

}

Is this answer helpful? 0 Yes | 0 No

Answer This Question

251 views

17⟩ The type of fire extinguisher, which would not be suitable for flammable liquids, is

* a) Dry powder

* b) Water

* c) Carbon dioxide

* d) Foam

Answer – b

Is this answer helpful? 0 Yes | 0 No

Answer This Question

214 views

18⟩ Prior to using an electric saw on a construction site, a user check finds that the insulation on the supply flex is damaged. The correct procedure would be to

* a) Replace the cord with a new one

* b) Report the damage to a supervisor after use

* c) Repair the cord with insulation tape

* d) Report the damage to a supervisor before use

Answer – d

Is this answer helpful? 0 Yes | 0 No

Answer This Question

179 views

19⟩ First aid points are indicated using signs bearing a white cross on a

* a) Yellow background

* b) Blue background

* c) Red background

* d) Green background

Answer – d

Is this answer helpful? 0 Yes | 0 No

Answer This Question

197 views

20⟩ When carrying out repairs to the base of a street lighting column it is essential to wear

* a) A safety harness

* b) High visibility clothes

* c) Gauntlets

* d) High voltage clothing

Answer – b

Is this answer helpful? 0 Yes | 0 No

Answer This Question

206 views

Electrical Engineering

Home Engineering Electrical Engineering

105 Electrical Engineering Questions And Answers

1⟩ Given the following Verilog code, what value of "a" is displayed?

2⟩ What is the difference between c = foo ? a b; and if (foo) c = a; else c = b;

3⟩ What is the difference between a Verilog task and a Verilog function?

4⟩ What is the difference between the following two lines of Verilog code?

5⟩ Using the given, draw the waveforms for the following versions of a?

6⟩ Given the following snipet of Verilog code draw out the waveforms for clk?

7⟩ Explain the differences between "Direct Mapped", "Fully Associative", and "Set Associative" caches

8⟩ Given the following FIFO and rules, how deep does the FIFO need to be to prevent underflowing or overflowing?

9⟩ Write a function to determine whether a string is a palindrome (same forward as reverse, such as "radar" or "mom")

10⟩ Write the code for finding the factorial of a passed integer. Use a recursive subroutine?

11⟩ Draw the state diagram for a circuit that outputs?

12⟩ Write a function to output a diamond shape according to the given (odd) input?

13⟩ Design a four-input NAND gate using only two-input NAND gates

14⟩ In C, explain the difference between the & operator and the * operator?

15⟩ Write the code to sort an array of integers?

16⟩ What is the difference between running the following snipet of code on Verilog vs Vera?

17⟩ The type of fire extinguisher, which would not be suitable for flammable liquids, is

18⟩ Prior to using an electric saw on a construction site, a user check finds that the insulation on the supply flex is damaged. The correct procedure would be to

19⟩ First aid points are indicated using signs bearing a white cross on a

20⟩ When carrying out repairs to the base of a street lighting column it is essential to wear

Quick Links:

Electrical Engineering

Home Engineering Electrical Engineering

105 Electrical Engineering Questions And Answers

1⟩ Given the following Verilog code, what value of "a" is displayed?

2⟩ What is the difference between c = foo ? a b; and if (foo) c = a; else c = b;

3⟩ What is the difference between a Verilog task and a Verilog function?

4⟩ What is the difference between the following two lines of Verilog code?

5⟩ Using the given, draw the waveforms for the following versions of a?

6⟩ Given the following snipet of Verilog code draw out the waveforms for clk?

7⟩ Explain the differences between "Direct Mapped", "Fully Associative", and "Set Associative" caches

8⟩ Given the following FIFO and rules, how deep does the FIFO need to be to prevent underflowing or overflowing?

9⟩ Write a function to determine whether a string is a palindrome (same forward as reverse, such as "radar" or "mom")

10⟩ Write the code for finding the factorial of a passed integer. Use a recursive subroutine?

11⟩ Draw the state diagram for a circuit that outputs?

12⟩ Write a function to output a diamond shape according to the given (odd) input?

13⟩ Design a four-input NAND gate using only two-input NAND gates

14⟩ In C, explain the difference between the & operator and the * operator?

15⟩ Write the code to sort an array of integers?

16⟩ What is the difference between running the following snipet of code on Verilog vs Vera?

17⟩ The type of fire extinguisher, which would not be suitable for flammable liquids, is

18⟩ Prior to using an electric saw on a construction site, a user check finds that the insulation on the supply flex is damaged. The correct procedure would be to

19⟩ First aid points are indicated using signs bearing a white cross on a

20⟩ When carrying out repairs to the base of a street lighting column it is essential to wear

BE THE FIRST TO KNOW

Quick Links: