Chapter 1 Flashcards
is the basis of computers, and computers are intrinsically
at the heart of digital systems
Digital Logic
are used in scientific calculations, commercial and business data
processing, air traffic control, space guidance and many other areas.
Computers
Characteristic of a _____________ is its manipulation of discrete elements of information. Such discrete elements may be electric impulses, the decimal digits, an alphabet, arithmetic operations or any other set of meaningful symbols
digital system
Discrete elements of information are represented in a digital system by physical quantities called __________. Electrical signals such as __________ and __________ are the most common.
signals, voltages, currents
The signals in all electronic digital systems have only two discrete values and are said to be _________.
binary
Most natural quantities and vary continuously. It can generally handle higher power than digital systems.
Analog systems
It can process, store, and transmit data more efficiently but can only assign discrete values to each point.
Digital systems
Digital circuits operate in the binary mode where each input and output voltage is either ___ or ___ . 1 and 0 designations represent the logical state which has a pre-defined voltage ranges.
1 or 0
A typical CD player accepts digital data from the CD drive and converts it to an analog signal for ______________.
amplification
Digital electronics uses circuits that have two states, which are represented by two different voltage levels called _____ and _____. The voltages represent numbers in the binary system.
HIGH and LOW
In binary, a single number is called a ____ (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.
bit
it is the change between the LOW and HIGH levels
Digital Waveforms
A _________ going pulse is one that goes from a normally LOW logic level to a HIGH level and then back again
positive
Series of pulses:
1) positive-going pulse
2) negative-going pulse
are not ideal but are described by the rise time, fall time, amplitude, and other characteristics.
Pulses
composed of pulses that repeats in a fixed interval called the period.
Periodic pulse waveforms
The ___________ is the rate it repeats and is measured in hertz.
frequency
is a basic timing signal that is an example of a periodic wave.
Clock
In addition to frequency and period, repetitive pulse waveforms are described by the amplitude (A), pulse width (tW) and duty cycle. Duty cycle is the ratio of tW to T.
Pulse
is the fraction of time that a system is in an “active” state. It is also the proportion of time during which a component, device, or system is operated.
Duty Cycle
is used to show the relationship between two or more digital waveforms,
Timing diagram
All logic circuit combinations are based on the three major types of logic gates. (3)
1) AND Gate
2) OR Gate
3) NOT Gate
True only if all input conditions are true.
AND Gate
True only if one or more input conditions are true.
OR Gate
Indicate the opposite condition
NOT Gate
And, or, and not elements can be combined to form various logic functions. A few examples are:
comparison function
Basic arithmetic functions
encoding function
decoding function
(DIP)
Dual-In-Line Package
(SOIC)
Small Outline IC
- 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 that fixed function devices.
Programmable logic devices (PLDs)
A PAL ( Programmable Array Logic) device is a form of ______ that uses a combination of a programmable AND array and a fixed OR array
PLD (Programmable Logic Device)
