Download Review of essential terms and concepts T103 Chapter 3

Review of essential terms and concepts T103
Chapter 3
1. Why is an understanding of Boolean algebra important to computer scientists?
1. Because computers are built as collections of switches that are either “on” or “off,” Boolean
algebra is a very natural way to represent digital information.
2. Digital circuits use low and high voltages, but for our level of understanding, 0 and 1 will suffice.
2. Which Boolean operation is referred to as a Boolean product?
AND operation
3. Which Boolean operation is referred to as a Boolean sum?
OR operation
4. Create truth tables for the Boolean operators OR, AND, and NOT.
5. What is the Boolean duality principle?
duality principle: The principle evident in Boolean identities where the product form and the sum
form have similar relationships.
6. Why is it important for Boolean expressions to be minimized in the design of digital circuits?
Because unnecessary product terms in the expression lead to unnecessary components in the
physical circuit, which turn yield suboptimal circuit.
7. What is the relationship between transistors and gates?
A chip is a small electronic device consisting of the necessary electronic component (transistors,
resistors, and capacitors) to implement various gates. And the relationship is that logic gates are
composed of several transistors.
8. What is the difference between a gate and a circuit?



A circuit is a path between two or more points along which an electrical current can be
carried
A gate is a small, electronic device that computes various functions of two-valued signals.
gates are the building blocks of circuits
9. Name the four basic logic gates.
AND gate, OR gate, NOT gate, XOR gate.
10. What are the two universal gates described in this chapter? Why are these universal gates
important?


NAND gate and NOR gate are the two universal gates
The universal gates are important because
1) Any circuit can be constructed using only those two gates (NAND gates or OR gates).
2) Universal gates are cheaper to build than other gates.
3) Complex integrated circuits are often much easier to build using the same building block (several
NAND gates or OR gates) rather than a collection of the basic building block.
11. Describe the operation of a ripple-carry adder. Why are ripple-carry adders not used in most
computers today?


ripple-carry adders is kind of adder to create a logical circuit using multiple full adders to add
N-bit numbers. Each full adder inputs a Cin, which is the Cout of the previous adder.
ripple-carry adders not used in most computers today because ripple-carry adders becomes
slow ones the number of bits is increased and there are faster methods are nowadays
implemented in computers (40% to 90%) faster than the ripple-carry adder.
12. What are three methods we can use to express the logical behavior of Boolean functions?
1. Truth table
2. Boolean expression (in sum of products form).
3. A logic diagram using gate symbols.
13. What are the difference between the a half-adder and a full-adder?


half-adder: a circuit to add two bits that produces two outputs, a sum and a carry.
full-adder: a circuit to three bits, one of which is a carry in, that produces two outputs, a sum
and a carry.
14. What do we call a circuit that takes several inputs and their respective values to select one
specific output line?
Name one important application for these devices. We call that circuit decoder. One of the
important application is “Chip selection”
15. What kind of circuit selects binary information from one of many input lines and directs it to a
single output line?
Multiplexer circuit.
16. How are sequential circuits different from combinational circuits?
combinational circuits: A logic device whose output is always based entirely on the given inputs.
sequential circuits: a logic device whose output is defined in term of its current inputs in addition to
its previous outputs.
17. What is the basic element of a sequential circuit?
Flip-flop is the basic component of sequential circuits
18. What do we mean when we say that a sequential circuit is edge-triggered rather than leveltriggered?
This mean it is allowed to change their states on either the rising or falling edge of the clock signal.
19. What is feedback?
feedback: this simply means the output of a circuit is fed back as an input to the same circuit.
20. How is a JK flip-flop related to an SR flip-flop?
JK flip-flop: is sequential circuit has modified the SR flip-flop to provide a stable state when both
inputs are 1
21. Why are JK flip-flops often preferred to SR flip-flops?
Because the JK flip-flop is a simple modification of the SR flip-flop to ensure the state J=K=1 is never
arises. It works just like a SR flip-flop and stores two bots of information, where J is serving as set
input and K serving as reset.
22. Which flip-flop gives a true representation of computer memory?
D flip-flop: is a true representation of physical computer memory.