# 07 - Practice Test

1. Logic is the foundation on which a computer system is built internally. Bits are switched __________________ using the binary 1's and 0's. In Boolean Logic, these translate into T (true) and F (false) statements.
`Boolean Logic is considered the very basis of computing. `

vertically

up and down

forward and backward

on and off

2. George Boole was a largely self-taught English mathematician, philosopher and logician and is best known as the ______________

author of The Laws of Thought (1854) which contains Boolean algebra

founder of the Binary (two digit) language

creator of the Boolean Von Neumann circuit used in modern CPUs

philosopher that asked questions about the nature of the universe and relativity

3. The keyword Bool represents a Boolean datatype in many programming languages and is named after George Boole.
`Note: Boolean variables can be either 'True'(1) or 'False'(0)`

TRUE

FALSE

4. Read the definition of a LOGIC CIRCUIT and decide whether it is true or false
```A logic circuit is a combination of logic gates.
```

TRUE

FALSE

5. In a statement like this: (A+B) . (C + D) - what do the brackets mean?

The brackets are there for aesthetic and artistic effect

The brackets mean that the expression inside them is processed LAST

It doesn't mean anything

That the brackets are done first (just like BODMAS rules in maths)

6. What is the boolean expression for this circuit? ….
`Note: that the '.' is an AND gate and a + refers to an OR gate`

A AND B

(A+B)+(C.D)

NOT Y = AB

(A+B) . (C + D)

7. What is the boolean expression for this circuit? …..

NOT C (A+B+C)

None of the above

(A + B) AND (NOT C)

(A+B) . NOT C

8. What is the boolean expression for this circuit? ……

(A + B) AND (NOT C)

None of the above

(AB + C)D

(A.B).C.D

9. What is the boolean expression for this circuit? …….

(A + B) AND (NOT C)

(A.B).C.D

None of the above

(AB + C)D

10. Transistors are made of semiconductor material, which is neither a good conductor of electricity nor a particularly good insulator. Transistors are usually made from silicon

TRUE

FALSE

11. If an electric signal is grounded, the signal flows through an alternative route to the ground where it can do no harm. When a signal is grounded it is pulled down to ______volts.

0

1

2

3

12. An AND gate and an OR gate both require two transistors. What about a NOT gate?

2

3

1

4

13. What logic gate does this truth table describe?
```-----Inputs----Output--
A    |   B   |    Q
=======================
0    |   0   |    0
=======================
0    |   1   |    1
=======================
1    |   0   |    1
=======================
1    |   1   |    1```

Not Gate

None of the above

Or Gate

And Gate

14. Logic gates are used to build complex logic systems, such as burglar alarms and combination locks. What are D and E in this complex logic gate?

D and E are logic gates

D and E are inputs

D and E are outputs but also inputs required to find Z

D and E are outputs

15. Looking at the logic gate and the truth table below, can you fill in the blank (for the question mark in the truth table)
```A	B	C	D	E	Z
0	0	0	1	0	1
0	0	1	1	0	1
0	1	0	1	0	1
0	1	1	1	1	1
1	0	0	0	0	0
1	0	1	0	0	0
1	1	0	0	0	0
1	1	1	0	?	1```

2

1

3

0

16. If the inputs are both 1, analyse the outputs as shown on the diagram and point out, if any, the error.

The output after the NOT gate at the top should be a 1 because it inverts the 0 to a 1

The last output C should be 0, because a 0 and 1 give a 0.

There are no errors. The outputs are all shown correctly

The last output C should be a 1 and 0 (e.g. 1,0) because it has more than one input coming in

17. Which colour/color box is showing an incorrect output?

The red box should be a 1

The yellow box should be a 1

The green box should be a 0

The white 0 at the end should be a 1

18. What is the boolean expression for this AND gate?

Y AND A

Y = A OR B

Y = A AND B

A AND B

19. What is the boolean expression for this OR gate?

A OR B = A

Y = A OR B

Y = A AND B

NOT Y = AB

20. Write the boolean expression for this circuit - -

None of the above

O = NOT (A AND B)

O = (A OR B) NOT

O = A AND B NOT

21. Write the boolean expression for this circuit - - -

O = A NOT B NOT B

O = NOT (A OR B)

O = NOT A AND NOT B

None of the above

22. Write the boolean expression for this circuit -

O = (NOT A) AND B

O = NOT B AND NOT A

O = NOT A OR NOT AND B

None of the above

23. What would the boolean expression be for the output C?

A = A AND B

C = A AND C

C = S AND B

C = A AND B

24. Write the boolean expression for this particular logic diagram (note that you can use brackets to denote an 'AND')
`Don't forget that a + is an OR gate and a . (or brackets) is an AND gate. `

C(D) + A

(AB + C)D

A(BD) + C

A + C (D)

25. In the following image we have an AND gate with two _____ A and B, and one _________

outputs / input

logic gates / output

logic gates / input

inputs / output

26. An '____' gate as shown in the image is requires either input A or B to be a 1 for the output to be 1.

AND

OR

NAND

NOT

27. A NOT gate, as shown, inverts signals. So if the input A is 1, the output would be:

2

Error

0

1

28. Most amazing laptops today have solid state drives. The magic gate behind SSDs is the ________

NOT

AND

NAND

OR

29. Digital systems are said to be constructed by using logic gates. These gates are the AND, OR, _____, NAND, NOR, EXOR and EXNOR gates.

NOP

GATE Y

GATE X

NOT

30. Logic gates are primarily implemented using diodes or transistors acting as electronic switches, but can also be constructed using vacuum tubes, electromagnetic relays (relay logic), fluidic logic, pneumatic logic, optics, molecules, or even mechanical el

FALSE

TRUE

31. Read the following excerpt and see if you can fill in the blanks.
```Learning tip about logic gates:
===============================
In a computer, we can also use a gate to control a flow and achieve
an end goal. We control the flow of an electric current as it goes
running around a circuit.
This gate in the world of digital electronics is known as a transistor
and can be in one of two states, on or off, or open or closed if you
like to think of it as a gate.
When a transistor is on, or open, then an electric current can flow through.
And when it’s off, then ____________________```

several electrical signals get through

a single electrical signal gets through

no current flows

no gates remain open

32. This excerpt explains how it all fits together. Fill in the blanks and be sure to read it all!
```Excerpt that explains how it all fits together
==================================================
When you string a bunch of these transistors together, then you
get what’s called a ____________, which lets you add, subtract,
multiply, and divide binary numbers in any way imaginable.
In a physical circuit,
these logic gates have:

Inputs.
=======
All logic gates require some kind of input value so that they
have numbers to compare. These figures come in the form of voltages. When
your input voltage is 0V, then it’s considered to be low, or 0. And when
you have a voltage of 5V as an input, then this is deemed to be high, or 1.

Outputs.
=========
Once a logic gate has a chance to process your input, it can then
make a decision on whether to open its gate or keep it closed. This output is
entirely determined by the type of logic gate you’re using, and some will only
open if you have two high voltages as an input, whereas others will only open
if you have a low voltage but not a high voltage as an input.```

Mega transistor

And Gate

CPU

Logic Gate

33. Read the guidance on the below image. Given the below what would A+B.C mean?
`note: think about how you would process this equation. Would you do the + or the . first? Refer to what you learned in Maths: BODMAS or BIDMAS`

A and B and C

A not C not B

A or B and C

A or B or C

34. Enter the missing value

1 –0 2 - 1 3 - 1,1

#1 –1 #2 - 0 #3 - 1,1

#1 –0 #2 - 1 #3 - 0,0

#1 –0 #2 - 0 #3 - 0,0

35. Enter the missing value

#4 0 #5 – 0 #6 -1

#4 1 #5 – 1 #6 -1

#4 1 #5 – 0 #6 -1

#4 1 #5 – 1 #6 -0

36. A NAND gate is the combination of which two gates?

OR and AND

OR and AND

AND and NOT

NOT and OR

37. The output of an OR gate is only 1 when both inputs are 1

FALSE

TRUE

38. A Half adder circuit is

An OR gate and a NOT gate

Half of an AND gate

A type of circuit which resembles (in look) half a snake

A circuit to add two bits together

39. An OR gate has one input and two outputs

FALSE

TRUE

40. A logic state can only be 1 or 0

True

FALSE