Exam 3 - BK Flashcards
What are the two digital logic states?
Logic 1 (ON)
Logic 0 (OFF)
How many bits in a Byte?
8
How many bits is a Nibble?
4
What are the two advantages of Digital signals?
- Error detection and correction (MOST IMPORTANT)
- Stored memory in semiconductors
What does ADC stand for
Analogue to Digital
What does DAC stand for
Digital to Analogue
List 2 common ADC circuits
- Successive Approximation Register (SAR)
- Dual Slope
What is the basic operation of an ADC
Converts an analogue signal voltage to a string of binary code depending on the value of the analogue input voltage
If the inputs to an AND gate are 1 & 0, what is the output
0
If the inputs to an OR gate are 1&1, what is the output
1
How many inputs and outputs are there in a NOT gate
1 Input, 1 Output
What is another name for a NOT gate?
Inverter
On a XOR gate, when the input is 1&1, what is the output
0
What is Fan-In
The number of inputs a logic gate can accept
What is Fan-Out
The number of inputs a logic gate can drive
What must be used if a logic gate has a High Fan-In of more than 10 inputs
A buffer
What is the disadvantage of a High Fan-In logic gate
Slower due to its complexity
What is the normal Fan-out output of any logic gate, and how can it be expanded?
Normal Fan-Out = 10
Can be expanded with a buffer
What is propagation delay?
Time required for a digital signal to travel from input to output
What problems does propagation delay cause in an asynchronous circuit?
Intermittent faults
Does propagation delay increase or decrease with temperature
Increase
Does propagation delay increase or decrease with output load increase
Increase
In a logic circuit, what are some advantages in keeping the number of components to a minimum?
- Keep costs low
- Reduce complexity
- Reduce size of power supply
- Reduce propagation delay
What is the most basic flip-flop that all other bi-stable latches and multi-vibrators are made from?
SR Flip Flop
(Set-Reset)
What does the term “Transparent” mean when talking about flip-flops?
Output responds immediately to input
Are SR Flip-Flops Synchronous or Asynchronous?
Asynchronous
How many inputs and outputs does and SR Flip-Flop have?
2 Inputs (Set-Reset)
2 outputs (Q - notQ)
Which 3 ways can the clock signal be read?
Edge Trigger:
-Positive Edge (Rising)
-Negative Edge (Falling)
Level Trigger:
- When clock pulse reaches a certain logic level (Usually 1)
How is a Gated SR Flip-Flop different from a standard SR Flip-Flop?
A clock signal input
How many inputs in a Gated SR Flip-Flop?
3 Inputs:
-Set
-Reset
-Clock (Enable) Input
What is the disadvantage to a Gated SR Flip-Flop that is fixed by adding inputs ‘Preset and Clear’
Uncertainty in switching
What is a disadvantage to a Gated SR Flip-Flop w/Preset&Clear that is fixed by using a D-type Flip-Flop?
Using a D-type Flip-Flop eliminates need for having 2 additional input for Preset and Clear by connecting an inverter between Set and Reset (or between J and K)
How many inputs to a D-type Flip-Flop?
2 Inputs:
Clock and ‘D’ input
How is a Master-Slave Flip-Flop constructed?
2 bi-stable SR circuits connected in a cascade
How does a T-Type Flip-Flop work?
Output changes state every application of a clock signal and latches onto that signal until another input signal is added
What can the T-type Flip-Flop also be used for?
Frequency Divider - Output frequency is half of input frequency
In a JK Flip-Flop, what happens when both J and K are 1
Q toggles
What does Clear and Preset do?
Cleared to 0 or Preset to 1 independently of clock signal
Is D-type transparent?
Yes
Where is the inverter placed in a data flip flop?
In-between S and R inputs
What are some uses for T-type?
Frequency Divider
Binary Counter
Is T-type commercially available?
No, can be made by connecting the J and K inputs together
What output condition must be avoided in a SR Flip-Flop?
S=0
R=0
- Invalid Output
What Flip-Flop was made to overcome the S=R=0 condition in a SR Flip-Flop?
JK Flip Flop
(Added clock signal)
What are the 4 outputs conditions of a JK Flip-Flop?
Logic 1
Logic 0
No Change
Toggle
What does the JK Flip-Flop suffer from?
It suffers from the timing problem dubbed ‘Race’
How is ‘Race’ in a JK Flip-Flop overcome
By keeping the timing pulse as short as possible by reducing the period.
This is done by increasing frequency.
What Flip-Flop is used to eliminate timing problems in a JK Flip-Flop?
Master-Slave Flip-Flop
Where does the Master circuit trigger on the clock pulse?
Triggers on positive edge of clock pulse
When does the Slave circuit trigger on the clock pulse?
Triggers on the negative edge
Where does the feedback go to on a Master-Slave circuit?
The output of the Slave circuit is fed back to the Master circuit
Is the Master-Slave Flip-Flop Synchronous or Asynchronous?
Synchronous
What is the most common use for a Square Wave?
Clock and Timing Signal
What is the duty cycle of a square wave?
50% duty cycle
What is the equation for finding the frequency of a square wave?
Frequency = 1 / (ON time + OFF time)
Is a rectangular wave symetrical?
No nigga
What is another name for the Positive and Negative wave half on a rectangular wave?
Mark and Space
What are rectangular waves used for in a circuit?
- Regulating power
(Higher duty cycle = Greater power applied) - Pulse Width Modulation
Are triangular waves symetrical?
Yes
What is the duty cycle of a triangular wave?
50%
Is a sawtooth wave symetrical?
No
What are sawtooth waves rich in?
Harmonics
What type of sawtooth wave is the most common?
Positive Ramp
What is the purpose of Triggers and Pulses?
To control the timing in a circuit
What are the characteristics of a Trigger?
- Very narrow pulse
- Swings either positive or negative
What are the characteristics of a Pulse?
- ONLY POSITIVE
- Shape of the pulse is determined by Mark-to-Space ratio
- Similar to a rectangle wave
What is a Schmitt Trigger used for?
Creating a clean square wave from an input
What 3 waves can a function generator make?
- Sinusoidal
- Triangle
- Square
How many inputs on a Schmitt Trigger
1 - Clock input
How many times does Q0 change state per line?
Every line
How many times does Q1 change state per line?
every 2 lines
How many times does Q3 change state per line?
every 8 lines
How many times does Q2 change state per line?
every 4 lines
What Flip-Flop configuration do counters use?
T-Type
(Toggle mode)
What does ‘mod’ mean when used in a counter
number of states
What are the two types of counters?
Asynchronous
Synchronous
What does a counter do?
It is a digital circuit which produces a Binary count
What does Asynchronous mean?
The clock pulses to the Flip-Flop arrive at different times
What does Synchronous mean?
Each Flip-Flop is clocked in at the exact same time
What is another name for an Asynchronous counter?
Ripple counter
What is a disadvantage to Asynchronous counters?
Takes time for the change of the clock pulse to change the output.
The device has to wait to count the ‘ripples’ before it can be used.
On what edge of the clock pulse is the UP counter changing states
Negative edge
(falling edge)
What does an UP/DOWN counter count?
Counts both up and down
On an UP/DOWN counter, how does it count up?
The Q output is steered to the next flip-flop’s clock
On an UP/DOWN counter, how does it count down?
The notQ output is steered to the next flip-flop’s clock
What makes a frequency divider useful for being used as a counter?
Because the Q outputs are multiples of the clock frequency, they can be used as a counter.
What is a general rule for the number a frequency divider can count?
The counter will divide by one more than it can count to
What are the 4 different types of Registers?
- Storage (Retains info but does not alter it)
- Shift (Moves it left/right)
- Series (Serial data is entered or removed1 bit at a time)
- Parallel (All the bits are entered or removed simultaneously
What is a Register?
Temporarily stores information using Flip-Flops
What is a Buffer Register?
Serves as a temporary store when transferring data between two units with different speeds or doing independent tasks
How is a Buffer Register made using flip-flops?
Parallel in - Parallel out
What are Shift Left/Right Registers
Allows data to be shifted left OR right by multiplying or dividing by the power of 2
How are Shift Left/Right Registers configured?
As D-Type flip flops
What are the two families used on Digital ICs
- CMOS (Complementary Metal-Oxide Silicone)
- TTL (Transistor-Transistor Logic)
What is the internal circuitry of CMOS ICs based off?
MOSFETS and FETS
What is the internal circuitry of TTL ICs based off?
NPN and PNP Bipolar Transistors
What is the advantages and disadvantages of CMOS
Advantages:
- Very low power consumption
- low propagation
Disadvantages:
- Slower operating speeds
What is the advantages and disadvantages of TTL
Advantage:
- Much faster operating speed
Disadvantage:
- Very high power consumption
What applications can CMOS be used for?
- Low power battery circuits
- High Frequency Tuning operation for switching speeds upwards of 100MHz
What is the 3rd output state added to ICs to allow them to be connected together with different output states?
High Impedance state (Hi-Z)
In Boolean logic, what does True (T) mean?
Logic 1, High
In Boolean logic, what does False (F) mean?
Logic 0, Low
What is the state in-between HIGH and LOW which has an unpredictable output which noise can affect?
No-mans land
What does the term source and sink mean?
weather a circuit is being supplied or is drawing from a previous or future stage
What are the 4 functional blocks of a Microprocessor?
- Store/Memory
- Control
- Arithmetic and Logic Unit (ALU)
- Input/output (I/O)
What is the integrated package of Microprocessors called?
- MPU (Microprocessor unit)
- CPU (Central Processing unit)
What is the purpose of busses in a Microprocessor?
Provides a path for the flow of information
What is the purpose of an I/O interface?
Provides a connection to the outside world
What is the definition of an Instruction?
An instruction is a number of discreet operations a computer is told to perform a given task
What is a Program?
A group of instructions that allows the computer to perform a specific task
What is a Computer Word?
A group of binary digits (Bit and Bytes) that occupy storage memory
What is an example of a Word Length?
8bit, 16bit, 32bit, 64 bit
What are the 3 Busses in a Microprocessor?
- Address Bus
- Data Bus
- Control Bus
What does the Address bus do?
Carries info from the CPU to the I/O to ensure the correct device is accessed
- UNIDIRECTIONAL
What does the Data bus do?
Carries instructions to CPU
- BIDIRECTIONAL
What does the Control Bus do?
Carries control signal from the CPU to the Memory and I/O to ensure it arrives at the CORRECT TIME
- UNIDIRECTIONAL
What is the most important section to a Microprocessor?
The Arithmetic Logic Unit (ALU)
What is the accumulator in a Microprocessor?
Main working register to store data
What is the Data Register in a Microprocessor?
Temporary storage for data coming from or going to the Data bus
What is the Instruction Decoder in a Microprocessor?
Converts the instructions (Binary) into the appropriate control information to the MPU
What is the Program Counter in a Microprocessor?
Keeps track of a program to ensure it follows in the CORRECT SEQUENCE
What is an Operand?
Data words that (aren’t instructions codes) operated on by an ALU
What is an Opcode?
Binary (or Hex) word which represents a Microprocessor instruction
What does a Volatile memory mean?
The contents of the data are lost after the power is removed
What does a Non-Volatile memory mean?
The contents of the data are not lost after the power is removed
Is RAM volatile or non-volatile?
Volatile
What are the two categories or RAM?
- Static RAM
- Dynamic RAM
How is info stored on Static RAM?
An array of Flip-Flops (either Bipolar or MOS)
For Static RAM, Is Bipolar or MOS faster?
Bipolar is faster but uses more power
How is info stores on Dynamic RAM?
In an array of capacitors
What is a downside to storing information in an array of capacitors?
Capacitors lose charge via leakage.
- It must be refreshed every few milliseconds, this requires additional circuitry
Which of the two types of RAM is best?
Dynamic RAM
- Faster, cheaper, uses less power
What does ROM stand for?
Read Only Memory
Is ROM volatile or non-volatile?
ROM is Non-Volatile
What are the 4 types of ROM
- Masked Programmed ROM
- Programmable ROM (PROM)
- Erasable PROM (EPROM)
- Electrically Alterable PROM (EAPROM)
What are the two types of ROM that cannot be altered?
- Masked Programmed ROM
- Programmable ROM (PROM)
Which types of ROM can be altered?
- EPROM
- EAPROM
How is a program stored in a Masked Programmed ROM?
Stored during manufacture to perform a dedicated function.
- Expensive unless done in a mass manufacture
How is information stored in a PROM?
Short pulses of high current pass through small resistive links and fuse them permanently.
How is a program erased on an EPROM?
Exposing EPROM under intense UV light erases ALL data stored (can be a downside)
What ROM should be used if only a portion of the data is to be altered?
EAPROM
- Small areas can be altered electrically instead of altering the whole fucking lot
What is firmware?
A special type of software that is RARELY CHANGED
