Logic Flashcards
1
Q
NOT Gate (Inverter) specs
A
- Output is opposite the input
2
Q
OR Gate specs
A
- Any high gives a high
3
Q
AND Gate specs
A
Any low gives a low
4
Q
NOR Gate specs
A
Any high gives a low
5
Q
NAND Gate specs
A
Any low gives a high
6
Q
XOR Gate specs
A
Any high gives a high but not both
7
Q
XNOR Gate secs
A
Any high gives a low but not both
8
Q
What does Boolean Algebra define?
A
Logic (AND, OR, NOT etc.) applied to anything that has only 2 states
9
Q
Logic (and computers) can also be accomplished _____ (DNA. neurons) or _____ or _____.
A
Organically
Optically
Chemically
10
Q
Complex problem involving many logic functions can be greatly simplified by applying?
A
Boolean Laws
11
Q
Idempotent rule (Redundancy rule)
A
AA = A A + A= A A1 = A A0 = A A + 1 = 1 A + 0 = A
12
Q
Law of Complementation
A
A(not A) = 0
A + (not A) = 1
(not not A) = A
13
Q
Demorgans Laws
A
AKA Alternate Logic
- To “demorganize” or determine the alternate logic for a gate:
1) Invert the inputs
2) Change the gate (or sign)
3) Invert the output
14
Q
Demorganization can only be applied to 2 levels of logic?
A
- a product of sums
- a sum of products
15
Q
Another method to Demorganize is to “________________”
A
Break the line and change the sign
You can not break more than one line at a time but you can break one line more than once in a single step
16
Q
Commutative Law
A
AB = BA A+B = B+A
17
Q
Distributed Law
A
A(B+C) = AB + AC
18
Q
Associative Law
A
A(BC) = C(AB)
19
Q
Laws of Absorption
A
A(A + B) = A
A + (AB) = A
20
Q
Human to machine =
A
Encoding
21
Q
Machine to human =
A
Decoding
22
Q
Human encoding forms
A
Numbers, letter, symbols
Video
Audio
23
Q
Machine decoding forms
A
Binary Octal Hex BCD ASCII
24
Q
Flip flops are used as ______ devices?
A
Memory
25
What are the 4 types of FFs?
1. SR NOR and NAND
2. Clocked RS
3. D type
4. JK
26
SR NOR and NAND are both what type of FF?
Asynchronous
27
SR NOR FF specs
- Active High
- Q is set with a 1 on S
- Q is reset with a 1 on R
- 00 is the memory/no change state
- 11 is the prohibited/illegal state
28
SR NAND FF specs
- Active Low
- Q is set to a 1 with a 0 on S
- Q is reset to a 0 with a 0 on R
- 11 is Memory function
- 00 is prohibited function
29
Clocked RS FF specs
- Synchronous
- When there is a 0 on CLK the outputs are frozen
- 1 on CLK and 0 on RS is memory state
- 111 is prohibited state
- Set with a 1 on CLK and S
- Reset with a 1 on CLK and R
30
JK FF does not have prohibited state, instead at 11 it is?
Toggle state
31
For JK FF, Q output is ____ the clock frequency?
1/2
32
What are the asynchronous parts of a JK FF?
PRS and CLR
33
PRS and CLR are active ____?
Low
34
0 on PRS Q =
1
35
0 on CLR Q =
0
36
A 1 on both PRS and CLR is?
Toggle mode for JK
37
What is the most popular gate to use to make all other gates?
NAND
| also least power consumption
38
A modulus 16 counter counts from ___ to ____
| A modulus 10 counter counts from ___ to ____
0-15
| 0-9
39
For an up counter, use the ____ function and the ___ output
CLR
| Q
40
For a down counter use the ____ function and the __ output?
PRS
| Not Q
41
What is a shift register?
A chain of FFs used to move binary data from one location to another
ex. calculator display is a shift left register
42
Serial Loading
- Data is entered 1 BIT at a time
| - An 8 BIT BYTE requires 8 clock pulses
43
Parallel Loading
- Data is moved simultaneously with one pulse
44
Serial Out
- Data is shifted out 1 BIT at a time
45
Parallel Out
Data is shifted out all at once
46
Simplifying circuits should always be done to?
- Reduce cost
- Power consumption
- Space
- Time
47
Another name for flip flop?
Latch
48
Astable multivibrator =
Oscillator
49
Monostable multivibrator =
One shot
50
Bistable multivibrator =
Flip flop AKA Latch
51
FFs build basic building blocks for what types of circuits?
Counters and Memory
| Shift Registers
52
Which FF has no invalid state?
JK
53
Which FF is the most widely used?
JK
54
On a timing or waveform diagram the horizontal distance stands for _____ and the vertical distance stands for ____?
Time
| Volts
55
The FF is a basic digital circuit with a _____ characteristic that can be used to store info.
Memory
56
The FF circuit is also called a?
Bistable multivibrator
57
The outputs are always _____ logic levels
Binary
58
What makes a FF synchronous?
A clock input
59
The clocked FF is normally in the sync or async mode?
Sync
60
FF are wired together to form?
Counters
| Registers
61
Name one application of the simple RS FF?
Bistable multivibrator
| Switch debouncer
62
What do shift registers do in a simple calculator?
Store temporary data
63
What are the 2 common classifications of shift registers?
Serial
| Parallel
64
Advantages and disadvantages of serial?
Slower but simple and less wiring
65
Advantages and disadvantages of parallel
Faster, more wiring, more complex
66
On a logic probe the green LED =
logic 0
67
On a logic probe the red LED =
Logic 1
68
The basic 555 configuration is used for?
Multivibrators
| ex. clocks, timers etc.
69
2 main types of logic gate families?
1. CMOS (Complimentary Metal Oxide Semi Cons)
| 2. TTL (Transistor Transistor Logic)
70
CMOS specs
- FET type transistors
- High efficiency
- Achieved using insulated gates
- Voltage supply 3V to 18V
71
Precautions to take when handling CMOS devices?
- Grounding straps with wrist bands
- Grounded mats on our work benches
- Static rated packaging
72
TTL specs
- Use BJT transistors
- More robust but not as efficient
- Voltage supply 5V + or - 0.25V
73
IC Pin Out =
How the gates are connected to the pins of the IC
74
IC Fan Out =
The number of gates that an output can drive
75
Operational amps are a relatively ___ power amp
Low (about 1/2W)
76
Op Amps are used as ?
Building blocks for industrial processes
- comparators
- integrators
- differentiators
77
For op amps the Gain, input Z, output Z, bandwidth are dependent on?
The external components we connect
78
2 types of op amp inputs?
Inverting
| Non-inverting
79
The output of an op amp is _______ times the difference between the inputs?
200,000
80
Inverting amp formula
```
Gain = Rf/Rin
Vout = -Vin(Rf/Rin)
```
81
Voltage follower op amp specs
Buffer
Gain = 1 (unity)
Used to isolate circuits
82
Non inverting amp formula
Gain = A = Rf/Rin + 1
83
Summing Amp formulas
Vout = - (V1 Rf/R1 + V2 Rf/R2 + V3 Rf/R3)
84
Summing amp if R1 = R2 = R3 = Rf then the voltages will be ?
Added together
85
Summing amp is R1 = R2 = R3 = 3 x Rf then the voltages will be?
Averaged
86
Integrator amp, Vout varies?
How long the input has been applied
87
Differentiator amp, Vout varies?
With how quickly the input is changing
88
An integrator op amp is essentially a?
low pass filter
89
Integrator op amp has more output if frequency is?
Lower
90
Integrator Vout formula?
Vout = -Vin x 1/RC x T
91
Integrator output is proportional to the?
Product of the amplitude and duration of the input signal (area under the curve)
92
Integrator op amp suffers from?
Drift , any DC offset voltage will cause the integrator to drift and eventually saturate
93
What is placed in parallel with the capacitor in a integrator op amp to reduce drift?
A high value resistor
94
A differentiator op amp responds to ?
rate of change of the input signal
95
A differentiator op amp is essentially a ?
High pass filter
96
for a differentiator op amp more output if frequency is?
Higher
97
differentiator op amp instantaneous output is proportional to?
Instantaneous rate of change at its input
98
differentiator op amp Vout formula?
Vout = -RC x (change in Vin/ change in time)
99
differentiator op amp suffers from?
High frequency noise gain
100
What will limit the high frequency noise gain on a differentiator op amp?
A resistor in series with the input capacitor
101
What kind of transistor are used in the TTL family of logic ICs?
BJTs (bipolar junction)
102
What kind of transistor are used in the CMOS family of logic gate ICs?
FET (mosfets)
103
Traditionally which of the two families of ICs has had the lowest power dissipation rating?
CMOS
104
Which of the two families has had the lower propagation delay?
TTL
105
The TTL family come in the ____ series. The military uses the ____ series?
7400
| 5400
106
The operating voltage of TTL ICs is?
5V +/- 0.25V
107
What is meant by the term noise margin as applied to logic gates?
Difference between valid input and output for highs and for lows
108
In general which family of ICs has the largest fan-out?
CMOS (50)
109
The CMOS family of ICs uses the _____ series and the ___ series?
4000A and 4000B
110
A typical fan-out for a standard TTL IC is about ____ and a CMOS is about ____?
10
| 50
111
The minimum output high of a TTL gate is?
2.4V
112
The minimum input high of a TTL gate is?
2.0V
113
The max output low of a TTL gate is?
0.4V
114
The max input low of a TTL gate is?
0.8V
115
Which logic gate family is most susceptible to damage from static electricity?
CMOS
116
Which logic gate is family is most likely to have errors introduced by noise signals added to the coupling connections?
CMOS
117
What should be done with an unused input to an OR gate?
Tied low
118
What else could you do with the unused OR gate input if you were not concerned with a fan out of a preceding gate?
Tied to another unit
119
What should be done with an unused input to an AND gate?
Tied high
