Chapter 2 Flashcards

1
Q

logic circuits are made up of ____

A

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

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2
Q

fundamental elements of a digital system are _____ and _____

A

input variable and output function

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3
Q

AND logic

A

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

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4
Q

OR logic

A

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

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5
Q

NOT logic

A

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

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6
Q

NAND gate

A

output is complement of the AND of the inputs

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7
Q

NOR gate

A

output is the complement of the OR of the inputs

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8
Q

XOR gate

A

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

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9
Q

what is the xor function equivalent to

A

AB’ + A’B

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10
Q

truth table

A

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

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11
Q

universal logic gate

A

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

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12
Q

NOT from NAND gates

A

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

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13
Q

AND from NAND gates

A
  • 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
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14
Q

OR from NAND gates

A
  • first not both inputs
  • then feed the not outputs into a third nand gate
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15
Q

NOT from NOR gates

A
  • same as NAND
  • connect inputs together
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16
Q

OR from NOR

A
  • same as AND from NAND
  • put inputs into one NOR gate then NOT the output from the first NOR gate
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17
Q

AND from NOR

A
  • same as OR from NAND
  • not each input, then feed them into the same NOR gate
18
Q

NAND from NOR

A
  • use same procedure to get AND from NOR, then NOT it
19
Q

NOR from NAND

A
  • use same procedure to get NOR from NAND then NOT it
20
Q

logic network analysis - timing diagrams

A

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

21
Q

propogation delay

A
  • 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
22
Q

what does the complement of a function look like?

A
  • apply demorgans theorem until all ands have become ors and all ors have become ands
  • the nots should change
23
Q

why is simplifying logic circuits important?

A
  • less cost
  • less size
  • less power consumption
  • less delay
  • speed is higher
24
Q

minterms

A
  • 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
25
SOP
- sum of products - sum of all minterms that result in the output being 1 - fully defines the design of the function
26
Standard SOP
- 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')
27
maxterms
- 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
28
POS
- product of sum - product of all maxterms that result in output being 0
29
Integrated circuits
- 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)
30
small scale integration
- number of gates fewer than 10 - limited by the number of pins available in the IC
31
medium scale integration
-number of gates 10 - 1000 - usually perform specific elementary digital operations (decoders, adder, multiplexer, register, counter)
32
large scale integration
- thousands of gates - digital systems such as processors, memory chips, programmable logic devices
33
very large scale integration (VLSI) and ultra large scale integration (ULSI))
- millions of gates - large memory arrays and complex microcomputer chips
34
digital logic families
TTL - transistor transistor logic ECL - emitter-coupled logic MOS - metal oxide semi-conductor CMOS - complementary metal oxide semiconductor
35
Fan-out
- number of inputs that can be connected to a single output
36
Fan-in
number of inputs available in a gate (aka number of inputs that can be connected to a circuit)
37
Power dissipation
power that must be available from the power supply for a gate to consume
38
propogation delay is inversely proportional to ______________
operating speed
39
noise margin
max external noise voltage added to an input signal that doesn't cause an undesirable change in the output
40
mos
- 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