GLOSSARY
| Access point | Mode in which a Wi-Fi device acts as an access point of a Wi-Fi network. It is the way in which Wi-Fi routers normally work and in which a mobile phone can be put to share the Internet with other devices. |
| Alternating current | Alternating current (abbreviated AC) is an electric current in which the magnitude and the direction vary cyclically, usually with a sinusoidal shape, ranging from a positive to a negative value passing through 0. As both current and voltage go through positive and negative values, it is no longer meaningful to talk about positive pole and negative pole as in direct current, so we talk about active line through which the difference in sinusoidal potential arrives and neutral line through which it returns. It is the way in which electricity normally reaches homes and industries. It is used instead of direct current because it is much easier to raise or lower its voltage through the use of transformers (devices based on parallel coils located on the same magnetic core but without an electrical connection), and for long distance distribution it is interesting to use very high voltages to minimize transport losses (since the intensity is lower for the same electrical power, by ohm's law, which causes less power to be lost in the small resistance of the transport cables). After the voltage rises to thousands of volts to transport it, the electricity that reaches our homes is converted back to 230 V (in Europe) or 120 V (in USA and other countries) so we can use it. The usual frequency of the alternating current used in Europe is 50 Hz and that used in America is 60 Hz. |
| Amp | Unit of measurement of electric current intensity in the international system |
| Analog (signal) | It is said of a signal that is continuous in time (it has values at all times) and that at any moment it can adopt any value in a given range (for example, if the range is between -1 and 1 volts, each point of the signal can be any number within that range). Most real phenomena (for example the position of a car, the temperature of a room or the voice of a person) can be represented by an analog signal. Computers do not work with analog signals, as they have too much information, so they must become digital signals by discarding information. |
| AND | Logical operation that, having as input two expressions of type True or False, returns True if the two entries are true or False if any of the entries is false. If applied on binary numbers, return 1 if both entries are 1 or 0 if either of the entries is 0 |
| API | An application programming interface (API) is library of programming procedures that a provider or maker of a website, system or hardware provides and documents so others can interface with his system or hardware. An API may be for a web-based system, operating system, database system, computer hardware, or software library. For example Google, Youtube, Facebook and Arduino have well know API to interface with their systems. |
| ASCII | ASCII (English acronym for American Standard Code for Information Interchange — American Standard Code for Information Exchange—), is a character set based on the Latin alphabet, as used in modern English. The ASCII code uses 7 bits to represent the most common characters. The first 32 codes are for non-printable characters, most of which are control characters that have an effect on how the text is processed (carriage return, line feed, etc.), plus another 95 printable characters that follow them in numbering (starting with the space character, then the most common symbols, numbers, other symbols, uppercase letters, more symbols, lower case letters and ending with some more symbol). |
| AT Commands | The AT command set is a language developed by the Hayes Communications company that practically became an open command standard for configuring and parameterizing modems. The characters "AT", which precede all commands, mean "Attention", and made this set of commands also known as AT commands. For example, to make a call, the command to send to the modem is ATD963877000 |
| Baseband signal | Electrical signal in which its frequency components range from 0 to a maximum frequency. Almost all the signals we work with in the real world are baseband signals. So the audio that we can hear goes from something more than 0 Hz to more or less 20,000 Hz (20 Kilohertz) and the standard definition video goes from 0 to 5.5 million hertz (5 Megahertz). |
| Binary (numbering system) | Numbering system that has 2 as its base and, therefore, uses the digits from 0 to 1. This implies that the number 2 is represented as 10, 3 as 11, 4 as 100 etc. It is the system used internally by all computer systems |
| Binary (signal) | It is said of a signal or variable that can only adopt two states, normally represented by 0 or 1. Computers work only with binary signals |
| Bit | Bit is the acronym for Binary digit (that is, ‘binary digit’). A bit, which can have two states, or 0 or 1, is the digit of the binary numbering system and is the minimum amount of information that can be transmitted. All the information that computers, microcontrollers and other digital systems work with is encoded in bits. |
| Bit mask | In computer science, a bit mask is a set of bits that, by means of an operation, allow to extract part of a set of binary data. Its operation in binary is simple, the bits of those positions that want to be extracted from the data are set to 1 in the mask and the rest to 0 and an AND operation is performed between the mask and the data. Since the AND operation returns a 1 if both bits are 1 and a 0 in the rest of cases, the result of this operation will be binary data that will contain only those bits of the original data in the positions where the mask had ones. For example, if the original data was 10110110 and the mask is 00001111, the data returned by the binary AND will be 0000 (0110), or, what is the same, the value of the last 4 bits of the original data. |
| Byte | A byte is a 8-bit group. Almost all digital systems usually work with bytes or units that are a multiple of several bytes called words (word sizes of 16, 32 or 64 bits are usually common, or, what is the same, 2, 4, or 8 bytes ) |
| Character code | The letters and other characters (numbers, accents, interrogations, etc.) of a text string are stored as numbers in the computer memory. To be able to represent them correctly, you need a conversion table that indicates which letter corresponds to each stored number, and this table is called a character code. The problem is that there are several standardized tables and, if we use the wrong table, the characters we recover will be wrong. With the letters of the alphabet, the most international symbols and the numbers there are usually no problems because almost all the character codes currently in use use the same numbers to represent the same letters (share the assignments of a basic character code called ASCII), but the accented letters, the ñ and other punctuation characters specific to Spanish or other languages are more problematic because they are not coded the same in the most used character code on the internet (the UTF-8) than in the character code that windows uses by default, with which we sometimes encounter problems of corrupted characters when the program that opens the document does not use the correct character code. |
| Closed loop control systems | A control system in which the control action depends on the output signal. The output to be controlled is compared to the input (desired value) and an error or difference is generated that is used to control the process, which gives stability to the control process against internal disturbances and variations. |
| Coil | A coil or inductor is a passive component of an electrical circuit that, due to the phenomenon of self-induction, stores energy in the form of a magnetic field. In direct current it behaves like a short circuit, being used in components that connect or disconnect other circuits using the magnetic field created to move a switch.In alternating current or with higher frequency electrical signals, it exchanges energy with the network, using it with different objectives, including creating circuits that generate waves (oscillators) or selecting a certain frequency range of a signal (in circuits called filters). |
| Compile | Translate code created in a programming language understandable by a human being to a code that the device that has to execute it understands , usually called machine code. Programming languages can be interpreted (that is, the code is converted when every instruction is executed) or compiled (that is, an intermediate step called compilation is performed in which all the code is converted at once and then executed in machine code). |
| Condenser | An electric capacitor is a passive device capable of storing energy in an electric field. It is formed by a pair of conductive surfaces, generally in the form of sheets or plates separated by an insulating material. In direct current it behaves like an open circuit. In alternating current or with higher frequency electrical signals, it exchanges energy with the network. It is used with different objectives, such as smoothing current peaks in transients (connection or disconnection moments), creating circuits that generate waves (oscillators) or selecting a certain range of frequencies of a signal (in circuits called filters). |
| Data type | Normally a variable is assigned a type of data to optimize the size reserved in memory and to be able to carry out content checks by assigning it a value or operating with it. The most common types of data are integer, number with decimals, number with decimals with improved precision, text, Boolean (true or false), unrestricted binary for audio, images, video, etc. or enumerated types built by the user (for example the months of the year or a list of colors). |
| DC | Direct current (abbreviated DC) refers to the continuous flow of electric charge through a conductor between two points of different potential and electric charge, which does not change direction over time. Unlike the alternating current, in direct current the electric charges (usually electrons) always circulate in the same direction, from the positive to the negative pole. It is the current that is commonly used in electronic circuits with low voltages, of the order of 3, 5 or 12 V. For this purpose, the alternating current available in the electrical network is converted with specific circuits. |
| Digital (signal) | It is said of a signal that is discrete and quantized, that is, that it is not continuous, since it only has values in certain instants of time, normally spaced at regular intervals and that, in addition, those values can only be chosen from those included in a set defined a priori (for example, if the range is between -1 and 1 volts, each point of the signal can only take one of the following values -1, -0.5, 0, 0.5 or 1 volts) |
| Diode | A diode is a two-terminal electronic component that allows the circulation of electric current through it in only one direction (direct polarization), blocking the passage if the current flows in the opposite direction (reverse polarization). For the current to circulate with direct polarization, the diode needs a minimum voltage between its terminals called threshold voltage. |
| Discreet (signal) | It is said of a signal that is not continuous, since it only has values in certain instants of time, normally spaced at regular intervals. The signal values in each of the instants can take any amount within a range (for example, if the range is between -1 and 1 volts, each point of the signal can be any number within that range). |
| Duplex (communication) | In a duplex communication system the communicating devices are capable of transmitting and receiving at the same time, establishing a simultaneous bidirectional communication, compared to a simplex system, in which only one way communication exists or semi-duplex, in which information can be transmitted in both directions but not simultaneously. |
| Duty cycle of a signal | In electronics, the duty cycle, useful cycle or work regime of a square wave is the relationship between the time the signal is in active state and the period of the signal. Its value is between 0 and 1, and is given by the following expression: Time in which the signal is high / Total wave cycle time. |
| Electric current | Flow of electric charge along a material. Transfer of charges (usually electrons) through a conductive medium that is generated by the existence of a difference in electrical potential between two points of the conductive medium. |
| Electric Current Intensity | Flow of electric charge along a material per unit of time. The electric current intensity is measured in Amps and is represented by the I. |
| Electric power | It is the amount of electrical energy delivered or absorbed by an element at a given time. The unit in the International System of Units is the watt or watt (W). It is calculated by multiplying the voltage by the intensity. P = V * I. Every electrical component has a maximum operating power above which it can be irreversibly damaged, so it is necessary to limit the voltage and / or intensity values when using it (taking into account Ohm V's law = I * R). |
| Electric resistance | Opposition to the flow of electric current through a conductive material due to the obstacles encountered by electric charges in their displacement. It is similar to mechanical friction. It is measured in ohms (Ω) and is represented by R. |
| Electric voltage | Also known as potential difference. It is a physical magnitude generated by the presence of an electrostatic field that gives us an idea of the force that the field produces on the electrons present in its sphere of influence. Its existence in a conductive environment produces the creation of electric currents that go from the point of greatest electrical potential (positive pole) to the one of lowest electrical potential (negative pole). It is measured in volts and is represented by V. The differential nature of the voltage implies that you always have to connect an electric circuit to two points or poles. |
| Electrical signal | An electrical signal that contains information can be interpreted as the superposition of many signals with different pure frequencies, in fact there is a mathematical tool to extract these frequency components. It is a concept that is very well understood if we think about music and the bass and treble controls and equalizers of music playback devices. The electrical signals have the majority of their power (and therefore their information) between two specific frequencies and the distance between those two frequencies is called bandwidth (for example the video has much more bandwidth than the sound because it has information relevant up to a much higher frequency). |
| electronic board | An electronic board based on a microcontroller is a printed circuit board that incorporates a microcontroller and a series of additional circuits that extend its functionality, adding input and output port, both analog and digital and additional sensors and actuators such as led lights or buzzers. |
| Feedback | See closed loop control systems. |
| Firmware | The firmware of a device is the software that directly handles the hardware. It is incorporated into a read-only non-volatile memory (whose content is not lost when the device is turned of)f. In computers it is called BIOS and is responsible for starting the machine and loading the operating system so that the operating system can work. |
| Frequency of a wave | Frequency is the number of repetitions per unit of time of any periodic event. |
| Github | Github is an internet service that allows you to develop software projects collaboratively by carrying out version control using software called Git. Github makes available to the development team a web page where the different versions of the developed software and its documentation can be uploaded. |
| Ground or neutral of an electrical circuit | In an electrical circuit, the second connection point of the power supply is called ground or neutral so that there is a potential difference. In circuits fed with direct current the ground is equivalent to the negative pole. Sometimes it is provided from a pin or pin of the circuit, sometimes there are several pins to provide a ground point to various systems or sometimes there is a line or bus that runs through the circuit providing ground connection at various points. |
| H bridge | An H-Bridge is an electronic circuit that is generally used to allow a direct current electric motor to rotate both ways, forward and reverse. It is built with 4 switches that, depending on which are open or closed, supply the motor with current in one direction or another. The H bridges are available as integrated circuits, but they can also be constructed from discrete components. |
| Hexadecimal (numbering system) | Numbering system that has 16 as its base and, therefore, uses the digits from 0 to 9 and the letters from A to F. This implies that the number 10 is represented as A, 11 as B and so up to 15 that is represented as F, then 16 is represented as 10, etc. It is used in computer systems to represent certain quantities. |
| Hysteresis | Hysteresis is the tendency of a material to retain one of its properties in the absence of the stimulus that has generated it. We can find different manifestations of this phenomenon, including magnetic hysteresis. The hysteresis phenomenon causes that the changes of a parameter against a stimulus do not occur for the same value when the stimulus value rises than when it lowers, for example, a certain parameter can change its state when the voltage rises above 2 volts and do not return to the initial state until the voltage is below 1 volt. |
| I2C | It is a serial communication bus that has a clock line and a data line. On this bus a master device initiates the communication with one or several slave devices. The master selects the slave to communicate with by sending his binary address on the first byte of the communication. |
| IDE | An Integrated Development Environment is a computer application that provides support and tools to the developer or programmer of a particular hardware or software. There are IDEs to program Arduino systems, to develop mobile applications in the Android operating system or IOs or to program desktop applications in C ++ language, for example. It usually has a graphical user interface (GUI) that simplifies the creation of code, gives access to a debug window (to detect and eliminate the errors of the created code), allows to easily incorporate code functions developed by others (libraries) or it helps us to control the versions of the programs, among other tools. |
| Inductor | See coil. |
| Led | A type of diode that emits light when it is powered. The first diodes emitted red light, but currently there are diodes that emit light of various colors: red, orange, yellow, green, blue, violet and white, even non-visible, ultraviolet or infrared light. The LEDs have a nominal voltage at which they work and that depends on the color. |
| Library code | The term library in programming refers to a set of functions related to a specific topic created by an external programmer, packaged together and that allows extending the functionality of a programming language in a simple way. Almost all programming languages provide a mechanism to easily incorporate external libraries into our programs. There are specific libraries to work with Big data, do machine learning, work with web pages and many other applications. |
| Limit switch | The limit switch or contact sensor is an electronic, pneumatic or mechanical device located at the end of the path of a moving element, such as a conveyor belt, with the aim of sending a signal when the element reaches the end of its path (for example to stop the motor that drives it). |
| Loop for | Programming structure that allows to repeat the execution of a certain code a predetermined number of iterations. |
| Microcontroller | A microcontroller (abbreviated μC, UC or MCU) is a programmable integrated circuit, capable of executing the orders recorded in its memory. It is composed of several functional blocks that fulfill a specific task. A microcontroller has the three main functional units of a computer: central processing unit, memory and peripheral input / output. |
| Motor torque | Torque is the moment of force exerted by an engine on the power transmission axis or, in other words, the tendency of a force to rotate an object around an axis, point of support, or pivot. |
| NOT | Logical operation that, having as input an expression of type True or False, returns the opposite. If applied on binary numbers, it returns 0 if the entry is 1 and 1 if the entry is 0. It is also known as denial. |
| Octal (numbering system) | Numbering system that has 8 as a base and, therefore, uses the digits from 0 to 7. This implies that the number 8 is represented as 10, 9 as 11, etc. It is used in computer systems to represent certain quantities. |
| Ohm | Unit of measurement of electrical resistance intensity in the international system. |
| Ohm's law | Equation that relates linearly the voltage, intensity and resistance of an electrical circuit. V = I * R |
| OR | Logical operation that, having as input two expressions of type True or False, returns True if either of the entries is true or False if the two entries are false. If applied on binary numbers, return 1 if either of the entries is 1 or 0 if the two entries are 0. |
| Parallel (interface) | A parallel interface is a type of connection between two devices in which several communication wires are used at the same time, transmitting several bits each time. |
| Period of a wave | The period is the time duration of each repetitive event, so the period is the reciprocal of the frequency 1 / F. |
| Phase of a wave | The phase indicates the instantaneous situation in the cycle, of a magnitude that varies cyclically, being the fraction of the period elapsed from the moment corresponding to the state taken as a reference. We can represent a cycle in a 360º circle, saying that “phase” is the difference in degrees between a point on this circle and a reference point, a 360º rotation is equivalent to a complete cycle. |
| PID control | PID stands for Proportional, Integral, Derivative. They refer to a closed loop control mechanism in which the signal that is fed back into the control loop is proportional to the output signal (P), or its integral (I) or its derivative (D) or a combination of this values. This achieves control systems that react to the current value of the output (proportional), its historical (integral) or a prediction of its future (derivative), which allows adjusting the reaction to errors in the system, controlling the oscillations that occur when there are sudden changes and adjust the stability of the system. The three actions or a combination thereof (P, PI, PD) can be used. |
| port | In electronics, each of the pins of an electronic circuit or the communication interfaces through which devices or applications send and receive data can be called a port (so that a port can be a physical interface of one or more pins, but also a logical interface). |
| Potentiometer | A potentiometer is a variable resistance. Normally it has three poles, two extreme poles between which the resistance is fixed and an intermediate pole in which the resistance varies with respect to the other two poles when operating a lever or rotating command. There are several laws of control: linear (resistance varies in the same way as the movement of the command), logarithmic (resistance varies as the logarithm of the movement of the command), etc. There are potentiometers of control, to interact with the circuits and potentiometers of adjustment, thought to adjust a circuit when leaving factory and not to be operated later. |
| Power of an electrical circuit | In an electrical circuit we call power to the point of the board or circuit from which the supply voltage is provided to the rest of the components. Sometimes the power is provided from a pin of the circuit, sometimes there are several pins to provide power to various systems or sometimes there is a line or bus that runs through the circuit providing power at various points. |
| Power supply | In an electrical circuit the power supply is the component that provides the electrical energy necessary for it to work. Normally the power supplies provide a constant electrical voltage, varying the intensity depending on the resistance of the circuit that connects to it, although there are constant current power supplies. |
| PPM | Pulse Position Modulation. It consists of a digital communication technique in which the information goes in the position of a pulse in an interval that is repeated periodically. One of the main difficulties of this technique is in the synchronization between sender and receiver to detect the position properly. |
| Programming loop | A loop or cycle, in programming, is a sequence that repeatedly executes a piece of code, until the condition assigned to that loop is no longer fulfilled. Normally two types of loop are used in programming, the while loop that is executed while a condition is being met and the for loop, which is executed a specified number of times specified in the declaration of the loop. There is a variant of the while loop called repeat until, which runs until a condition is met. |
| Push-Button switch | A momentary electrical switch is called a push-button that is only activated while operating its command. |
| PWM | Pulse Width Modulation. It consists in varying the proportion of time in which a train of periodic pulses (either a square or sine wave) is active, that is, if we have a square signal that goes through a high state and then a low state periodically , we change how much percentage of that period will be in a high state and how much in a low state. This technique can be used to transmit information, but also to regulate the amount of energy that is sent to a load, controlling with that percentage, for example, the speed of rotation of an electric motor. |
| Relay | It is an electrical switch controlled by another electrical circuit (which activates an electromagnet controlled by a coil). It allows to control an electrical circuit that requires more power with a smaller electrical signal, which is used to control electrical loads that demand more power with circuits that cannot provide it directly (such as a light bulb, a motor or a heater from a microcontroller) . It also allows you to control devices that require alternating current to operate from a device that works with direct current. |
| Resistor | It is an electronic component designed to introduce a specific electrical resistance between two points of an electrical circuit. In other cases, such as irons, heaters, etc., resistors are used to produce heat taking advantage of the Joule effect. It is a material formed by carbon and other resistive elements to opose the current passing through it. |
| RGB | Acronym of the colors Red (Red), Green (Green) and Blue (Blue). It is said of a system capable of representing any color by combining different proportions of each of these 3 colors. White is achieved by combining the same amount of each of the three. |
| Serial (communication) | Communication protocol in which the bits are sent one by one sequentially using the same communication channel. |
| Signal bus | Digital system that transfers signals, usually consists of cables or printed board tracks. It can be serial, using a single cable or track to perform the transmission or parallel, using several cables or tracks to transfer several bits simultaneously. The difference between a parallel bus and several serial buses used in parallel is that in the parallel bus synchronization of all lines is common. |
| Signal filter | An electrical circuit designed to select a certain frequency range of an electrical signal is called a filter, discarding the other frequency components. There are low pass filters (they keep the frequency components located below a given one), high pass (they keep frequency components located above a given one), passband (they keep frequency components located between two given frequencies ) or band-stop (eliminate frequency components located between two given frequencies). |
| Sine wave | In mathematics the curve that represents the sine function and also the function itself is called sinusoid or sine. It is a curve that describes a repetitive oscillation that goes from a maximum to a minimum passing through zero. |
| Sinusoid | See Sine Wave. |
| Solenoid | See coil. |
| SPI | The SPI Bus (Serial Peripheral Interface) is a communications standard, mainly used for the transfer of information between integrated circuits in electronic equipment. It includes a clock line to synchronize the communication, a line for incoming data, a line for outgoing data and a select chip pin for each of the slave devices with which the processor wishes to communicate, pin that connects or disconnects the operation of that specific slave device. In this way, this standard allows communication with several devices using a line for the clock, other for incoming data and another for outgoing data only. It is faster than the I2C bus. |
| SSID | The SSID (Service Set Identifier) is a 32-character sequence that identifies the set of devices that communicate using the services of a Wi-Fi wireless access point (what is known in colloquial terms as "Wi-Fi network"). |
| Station mode | Mode in which a Wi-Fi device acts as a client station of a Wi-Fi network. It is the way in which computers and mobile phones are normally connected to a Wifi network. |
| switch | Electric device that allows to interrupt an electric current. They can be normally open (if the switch is not activated there is no current ) or normally closed (if the switch is not activated there is a current). Have one or several poles (open or close several lines at once) or connect an input to one of several outputs or output to one of several inputs (in this case it is called a double / triple / etc switch). Normal switches change state when activated and remain in the new state until activated again. |
| Thyristor | Semiconductor switching device used to drive high power. They are unidirectional devices that can only conduct current in one direction and that have a third terminal called a door that allows switching on. Once activated, they continue to drive until the input current disappears (even if the door current is not present). They can be used to rectify the alternating current and convert it into direct current. |
| Transformer | The transformer is a device that converts the alternating electrical energy (AC) of a certain voltage level into alternating energy of another voltage level, based on the phenomenon of electromagnetic induction. It consists of two coils of conductive material, wound on a closed core of ferromagnetic material, but electrically isolated from each other .The only connection between the coils is the common magnetic flux established in the core. In an ideal transformer the electrical power is maintained, so the input power is equal to that obtained at the output. Real machines have a small percentage of losses, depending on their design and size, among other factors. |
| Transistor | The transistor is a semiconductor electronic device used to deliver an output signal in response to an input signal. It fulfills functions of amplifier (to amplify a signal), oscillator (to generate a periodic wave), switch (to activate or deactivate a signal) or rectifier (to convert alternating current into direct current). It has 3 pins or ports, called collector, emitter and base. Depending on its configuration, it can, among other things, amplify the signal that reaches the base and deliver it between emitter and collector or change the state of the signal between emitter and collector from open to closed depending on the signal you have in the base (this is the mode of operation used in computers, in fact the microprocessors are sets of millions of combined transistors). |
| Triac | Semiconductor switching device used to handle high power alternating current. They have a third terminal called gate that allows switching on. Its internal structure somewhat resembles the arrangement that would form two thyristors in opposite directions. |
| UART | UART stands for Universal Asynchronous Receiver-Transmitter, it is the device that controls the serial ports and devices. The main functions of the UART chip are: handle the interruptions of the devices connected to the serial port and convert the data in parallel format, transmitted to the system bus, in serial format data, so that they can be transmitted through the ports and vice versa. |
| Variable | A variable in programming is a portion of the memory of a computer or microcontroller to which a name is assigned and which allows a value to be stored and retrieved and modified later. Normally a variable is assigned a type of data (integer, number with decimals, text, Boolean, binary) to optimize the size reserved in memory and to be able to carry out content checks when assigning a value or operating with it. Depending on the programming language there are conventions on the values that the name of a variable can adopt (if uppercase letters can be used, characters other than letters or numbers, maximum name size, etc.) |
| Vector in programming | A vector in programming is a data structure that contains several elements of the same type and that has an index system that allows you to retrieve any of its elements easily without having to recover the previous ones. Each item can be retrieved by the position it occupies. You can make vectors that contain vectors in their elements, which allows you to make multidimensional data matrices (that is, we can have a vector of the form i = ((2,3), (1,4), (3,5) ), so that if the indexes start at 0, the element i [0] [0] would be equal to 2 and the i [1] [1] equal to 4). A text string is a character vector. |
| Volt | Unit of measurement of voltage (electrical voltage) in the international system. |
| While loop | Programming structure that allows repeating the execution of a certain code while a condition is met. |
| XOR | Logical operation that, having as input two expressions of type True or False, returns True if the two entries are different and False if the two entries are equal. If it is applied to binary numbers, it returns 1 if the entries are 1 and 0 or 0 and 1 and 0 if the two entries are 1 or if the two entries are 0. Therefore, it is also known as Exclusive OR. |