Chapter 2

Question 1

logic circuits are made up of ____

Answer 1

logic gates - fundamental building blocks that carry out the logic operations

Question 2

fundamental elements of a digital system are _____ and _____

Answer 2

input variable and output function

Question 3

AND logic

Answer 3

if both (or all) inputs are 1, then output is 1
otherwise output is 0
represented by multiplication
two gates in series

Question 4

OR logic

Answer 4

if any inputs are 1, then output is 1
if all inputs are 0, then output is 0
represented by addition
two gates in parallel

Question 5

NOT logic

Answer 5

switches the input’s value from 0 to 1 or 1 to 0
aka the complement of a variable

Question 6

NAND gate

Answer 6

output is complement of the AND of the inputs

Question 7

NOR gate

Answer 7

output is the complement of the OR of the inputs

Question 8

XOR gate

Answer 8

output is 1 if an odd number of input variables is 1
represented with a circle around an addition symbol

Question 9

what is the xor function equivalent to

Answer 9

AB’ + A’B

Question 10

truth table

Answer 10

used to demonstrate the output for each possible combination of inputs of a combinational circuit

Question 11

universal logic gate

Answer 11

gates that can be used to implement the function of and, or, and not

Question 12

NOT from NAND gates

Answer 12

both inputs of NAND gate are the same (split input into to wires, then feed into NAND)

Question 13

AND from NAND gates

Answer 13

• first have A and B go into 1 NAND Gate, then feed output from 1st NAND gate (AB)’ into both inputs of 2nd NAND gate((AB’)’) = AB

Question 14

OR from NAND gates

Answer 14

• first not both inputs
• then feed the not outputs into a third nand gate

Question 15

NOT from NOR gates

Answer 15

• same as NAND
• connect inputs together

Question 16

OR from NOR

Answer 16

• same as AND from NAND
• put inputs into one NOR gate then NOT the output from the first NOR gate

Question 17

AND from NOR

Answer 17

• same as OR from NAND
• not each input, then feed them into the same NOR gate

Question 18

NAND from NOR

Answer 18

• use same procedure to get AND from NOR, then NOT it

Question 19

NOR from NAND

Answer 19

• use same procedure to get NOR from NAND then NOT it

Question 20

logic network analysis - timing diagrams

Answer 20

tracks the sequential series of 0 and 1 for input and the output for those inputs

Question 21

propogation delay

Answer 21

• t(pd)
• time for a change in the input of a gate to propagate to the output
• there are high to low and low to high propagation delays

Question 22

what does the complement of a function look like?

Answer 22

• apply demorgans theorem until all ands have become ors and all ors have become ands
• the nots should change

Question 23

why is simplifying logic circuits important?

Answer 23

• less cost
• less size
• less power consumption
• less delay
• speed is higher

Question 24

minterms

Answer 24

• products of all variables
• labelled as a product of the variables, when variable is 0, it is x’, when the variable is 1, it is x

Question 25

SOP

Answer 25

• sum of products
• sum of all minterms that result in the output being 1
• fully defines the design of the function

Question 26

Standard SOP

Answer 26

• has all variables represented in each term
• not the simplified version
• can be obtained from a simplified version by multiplying each term with the missing variable in the form (A + A’)

Question 27

maxterms

Answer 27

• sum of the variables for each result
• if variable’s value is 0, it is represented by x
• if value is 1, its represented by x’
  eg. x + y + z

Question 28

POS

Answer 28

• product of sum
• product of all maxterms that result in output being 0

Question 29

Integrated circuits

Answer 29

• IC is fabricated on a die of a silicon semiconductor crystal (AKA a chip) containing the electronic components for constructing digital gates
• the gates are interconnected to form the required circuit
• chip mounted on a container and connections are welded to external pins (number of pins varies)

Question 30

small scale integration

Answer 30

• number of gates fewer than 10
• limited by the number of pins available in the IC

Question 31

medium scale integration

Answer 31

-number of gates 10 - 1000
- usually perform specific elementary digital operations (decoders, adder, multiplexer, register, counter)

Question 32

large scale integration

Answer 32

• thousands of gates
• digital systems such as processors, memory chips, programmable logic devices

Question 33

very large scale integration (VLSI) and ultra large scale integration (ULSI))

Answer 33

• millions of gates
• large memory arrays and complex microcomputer chips

Question 34

digital logic families

Answer 34

TTL - transistor transistor logic
ECL - emitter-coupled logic
MOS - metal oxide semi-conductor
CMOS - complementary metal oxide semiconductor

Question 35

Fan-out

Answer 35

• number of inputs that can be connected to a single output

Question 36

Fan-in

Answer 36

number of inputs available in a gate (aka number of inputs that can be connected to a circuit)

Question 37

Power dissipation

Answer 37

power that must be available from the power supply for a gate to consume

Question 38

propogation delay is inversely proportional to ______________

Answer 38

operating speed

Question 39

noise margin

Answer 39

max external noise voltage added to an input signal that doesn’t cause an undesirable change in the output

Question 40

mos

Answer 40

• metal oxide semiconductor
• a transistor with 3 terminals:
  1. source - input terminal
  2. drain - output terminal
  3. gate - terminal where an electrical signal is applied to control current flow from source to drain