TEST I mid term Flashcards
Understand the terminology
1965
–
Moore’s Law
which states that the number
of transistors on a chip doubles about every two
years, the law is born when Intel’s Gordon Moore
made a prediction about the semiconductor
business that still holds true today
analog Quantities
Most natural quantities that we see are analog and vary continuously. Analog systems can generally handle higher power than digital systems
What kinds of data do we need to represent?
Logical – true, false – Numbers – signed, unsigned, integers, floating point, complex, rational, irrational, ... – Text – characters, strings, ... – Instructions – Images – pixels, colors, shapes, ... – Sound
Data type:
representation
and
operations
within the computer
Analog and Digital Systems combination
Many systems use a mix of analog and digital electronics to
take advantage of each technology. A typical CD player
accepts digital data from the CD drive and converts it to an
analog signal for amplification
Binary Digits and Logic Levels
In binary, a single number is called a bit (for binary digit). A bit can have the value of either a 0 or a 1, depending on if the voltage is HIGH or LOW
Digital Waveforms
Digital waveforms change between the LOW and HIGH
levels. A positive going pulse is one that goes from a
normally LOW logic level to a HIGH level and then back
again. Digital waveforms are made up of a series of pulses
Pulse Definitions
Actual pulses are not ideal but are described by the rise time,
fall time, amplitude, and other characteristics
how many states does a collection on n bits have
A collection of n bits has 2n
possible states
Timing Diagrams
A timing diagram is used to show the relationship between
two or more digital waveform
Basic Logic Functions
AND - True only if all
input conditions
are true.
OR- true only one or more input conditions are true
NOT- indicates the opposite of a condition
Examples of Basic System Functions
- The comparison function
- Basic arithmetic functions
- The encoding function
- The decoding function
What are the types of integrated circuits
DIP chips and surface mount chips
What is PLC
Programmable logic devices (PLDs) are an alternative to
fixed function devices. The logic can be programmed for a
specific purpose. In general, they cost less and use less
board space
than
fixed function devices.
Gate
A logic circuit that performs a basic logic
operations such as AND or OR.
Fixed -function
logic
A category of digital integrated circuits having
functions that cannot be altered
Compared to analog systems, digital systems
a. are less prone to noise
b. can represent an infinite number of values
c. can handle much higher power
d. all of the above
are less prone to noise
The number of values that can be assigned to a bit are
a. one
b. two
c. three
d. ten
2
The time measurement between the 50% point on the
leading edge of a pulse to the 50% point on the trailing edge
of the pulse is called the
a. rise time
b. fall time
c. period
d. pulse width
pulse Width
The time measurement between the 90% point on the
trailing edge of a pulse to the 10% point on the trailing edge of
the pulse is called the
a. rise time
b. fall time
c. period
d. pulse width
fall time
The reciprocal of the frequency of a clock signal is the
a. rise time
b. fall time
c. period
d. pulse width
period
If the period of a clock signal is 500ps, the frequency is
a. 20 MHz
b. 200 MHz
c. 2 GHz
d. 20 GHz
2GHz
AND, OR, and NOT gates can be used to form
a. storage devices
b. comparators
c. data selectors
d. all of the above
- storage devices
- comparators
- data selectors
A shift register is an example of a
a. storage device
b. comparator
c. data selector
d. counter
storage device
A device that is used to switch one of several input lines to a single output line is called a a. comparator b. decoder c. counter d. multiplexer
multiplexer
For most digital work, an oscilloscope should be coupled to the signal using a. ac coupling b. dc coupling c. GND coupling d. none of the abov
dc coupling
point
number
A number representation based on scientific
notation in which the number consists of an
exponent and a mantissa
Hexadecimal
A number system with a base of 16
Octal
A number system with a base of 8
BCD
Binary coded decimal; a digital code in which each
of the decimal digits, 0 through 9, is represented by
a group of four bits.
Alphanumeri
Consisting of numerals, letters, and other
characters
ASCII
American Standard Code for Information
Interchange; the most widely used alphanumeric
code.
Parity
In relation to binary codes, the condition of
evenness or oddness in the number of 1s in a code
group.
Cyclic
redundancy
check (CRC)
A type of error detection code.
The Inverter
The inverter performs the Boolean NOT operation. When the input is LOW, the output is HIGH; when the input is HIGH, the output is LOW.
-
the Boolean expression for an inverter is X = A.
The AND Gate
shown with a” .”
The AND gate produces a HIGH output when all inputs are HIGH; otherwise, the output is LOW. For a 2-input gate, the truth table is
Thus, the AND operation is written as X = A .B or X = AB.
uses of the And gate
The AND operation is used in computer programming as a selective mask. If you want to retain certain bits of a binary number but reset the other bits to 0, you could set a mask with 1’s in the position of the retained bits.
The OR Gate
shown with a +
The OR gate produces a HIGH output if any input is HIGH; if all inputs are LOW, the output is LOW. For a 2-input gate, the truth table is
Thus, the OR operation is written as X = A + B.
The NAND Gate
shown with an over bar covering the expression.
The NAND gate produces a LOW output when all inputs are HIGH; otherwise, the output is HIGH. For a 2-input gate, the truth table is
Thus, the NAND operation is written as X = A .B (Alternatively, X =AB.)
The NOR Gate
The NOR operation is shown with a plus sign (+) between the variables and an overbar covering them
The NOR gate produces a LOW output if any input is HIGH; if all inputs are HIGH, the output is LOW. For a 2-input gate, the truth table is
Thus, the NOR operation is written as X = A + B.
The XOR Gate
The XOR operation is written as X = AB + AB.
The XOR gate produces a HIGH output only when both inputs are at opposite logic levels. The truth table is
The XNOR Gate
X = AB + AB
The XNOR gate produces a HIGH output only when both inputs are at the same logic level.
Programmable Logic Device (PLD)
A Programmable Logic Device (PLD) can be programmed to implement logic. There are various technologies available for PLDs. Many use an internal array of AND gates to form logic terms. Many PLDs can be programmed multiple times.
