Difference between revisions of "Glossary"
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Command Line Interface. A type of user interface in which the user types commands at a prompt. Also known as a [[#CUI|
Command Line Interface. A type of user interface in which the user types commands at a prompt. Also known as a [[#CUI|CUI]].
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A user interface operated exclusively with a keyboard by typing commands at a prompt or selecting options from a menu, as opposed to a [[#GUI|Graphical User Interface]]. Also known as a [[#CLI|
A user interface operated exclusively with a keyboard by typing commands at a prompt or selecting options from a menu, as opposed to a [[#GUI|Graphical User Interface]]. Also known as a [[#CLI|CLI]].
Revision as of 20:21, 25 August 2017
This page provides a glossary of terms.
The Restart Wiki tries to assume no previous knowledge, only a willingness to learn, and so we try to introduce and explain technical terms as we go along. But you might dip in and out or read the end of an article before the beginning, or you might consult other sources containing unfamiliar terms.
So this page gathers together as many technical terms as possible that you might come across in your fixing-related research, cross-referenced and linked in to main wiki articles where relevant.
You will find your favourite search engine or Wikipedia also to be valuable resources for looking up unfamiliar terms - those will often give you more detail.
Glossary of Terms
|0 - 9|
See Zero Day.
Alternating Current. An electrical supply which reverses direction many times per second. See AC and DC in the Wiki.
A type of malware which presents you with unwanted advertising that you never knowingly agreed to receive.
Spare parts, consumables or accessories for an item not manufactured and sold by the item's manufacturer, but by a third party.
The unit of electric current, i.e. the quantity of electricity passing, a bit like the amount of water flowing in a river. See Electric circuits, volts amps watts and ohms in the Wiki.
A positive electrode.
Bayonet Cap. A type of lamp base fitted with a push-and-twist action. There are several sizes but the 22mm diameter size is much the commonest. See Types of bulb in the Wiki.
A number system using only the digits 0 and 1, well suited to computers as they can represent those digits by the on and off states of a switch.
Basic Input/Output System. A program built in to PCs up until around 2011, which controls the PC prior to booting and initiates the boot process. (Newer computers use UEFI). See BIOS vs UEFI in the Wiki.
Another name for a junction transistor.
A binary digit, representing one of two values or states, such as 1/0, or yes/no, or love/hate Marmite.
A personal area networking protocol allowing an individual's personal devices to communicate with one another.
Short for Robot. A computer which has been compromised in order to use its Internet connection for spreading spam or malware. Usually it will be one of many such computers comprising a "botnet", under the control of a "bot herder".
To "brick" a device is to render it completely useless, i.e. as much use as a brick.
A type of DC motor which uses an electronic circuit to switch the current between several coils in order to keep the motor turning, instead of using a commutator and brushes to perform this function. See DC and Universal (AC/DC) Motors in the Wiki.
8 bits, which can be used to represent a single letter, number or punctuation mark, or a number between 0 and 255, or anything else that can have up to 256 values.
A negative electrode.
Electricity really hates piling up, so it will only flow if it can go around a complete circuit and come back to where it started.
A vacuum cleaner, for example, may contain several paths or "circuits" around which the current can flow, and a computer may contain a huge number. A circuit diagram is a picture of all those paths (or some of them) allowing you to understand how it works.
Command Line Interface. A type of user interface in which the user types commands at a prompt. Also known as a Character User Interface or CUI.
|Compact Florescent lamp||
A type of light bulb consisting of a florescent tube bent into a compact shape. More efficient than traditional filament lamps but still falling well short of newer LED lamps. See Types of bulb in the Wiki.
A material which conducts electricity. Metals and carbon are conductors.
An intentional low resistance electrical path between two points in a circuit. A continuity tester is a device which tests for continuity, often giving an audible beep when it is found.
Central Processing Unit. The "brains" of a computer, which executes a computer program.
Cathode Ray Tube. The image-producing device in old fashioned televisions, computer monitors, radar sets and oscilloscopes, consisting of an evacuated glass enclosure in which electrons are fired at a flourescent screen to create the image. Superseded by much less bulky LCD displays.
A user interface operated exclusively with a keyboard by typing commands at a prompt or selecting options from a menu, as opposed to a Graphical User Interface. Also known as a Command Line Interface or CLI.
Alternative software to the operating system provided by the vendor for a device such as a smartphone.
Digital Audio Broadcasting. The standard used for digital broadcast radio.
Direct Current. An electrical supply which goes in one direction only. See AC and DC in the Wiki.
A Denial of Service attack launched via many different computers across the Internet, so increasing its power and making it harder to defend against.
The number system we commonly use, based on the digits 0 - 9.
A 2-terminal electronic component which switches from a non-conducting to a conducting state when a certain voltage is applied, then remains conducting until the current is switched off. Commonly used in conjunction with a triac in dimmer switches.
An insulating material in which the positive and negative charges in the atoms or molecules can be displaced slightly from their natural positions by an electric field, causing the material as a hole to exhibit an electrical charge.
A 2 terminal electronic component allowing a current to flow in one direction but not the other. See Diodes and Rectifiers in the Wiki.
A thing with two opposite ends, such as a magnet (with North and South poles), a molecule with a positive charge at one end and a negative charge at the other, or a type of aerial consisting of two rods placed end to end.
The process of recovering an audio or TV signal (for example) from the RF signal received from an aerial.
Digital Light Processing. A class of data projector using a DMD to produce the image.
Digital Micromirror Device. An imaging device which contains a tiny electrically operated mirror to control the brightness of each pixel.
Dead on Arrival. A brand new item which fails to work when first switched on.
Denial of Service. An attack which renders a service (such as a website) unusable for its proper purposes. See also DDOS.
See Ground loop.
A type of display, usually monochrome only, commonly used in e-book readers. It has the advantage of using very little power, and can be viewed by reflected ambient light rather than needing an active backlight.
Tamed magic. Well, mostly tamed.
A conducting liquid containing negative and positive ions, such as the liquid in a battery
A coil of wire wound around an iron core. A current passing through the coil magnetises the iron for only as long as the current flows. Typically used in electro-mechanical devices such as toasters, where it holds the lever down while the toast is toasting.
(Often abbreviated to EM wave.) A kind of wave in space in which energy is continually exchanged between electric and magnetic fields in the same sort of way as energy in a ripple on a pond is continually exchanged between gravity and momentum. Radio waves, light, x-rays and gamma rays are all EM waves of different wavelengths.
A sub-atomic particle carrying a negative electrical charge. A flow of electrons constitutes an electric current.
|Electronically Commutated Motor||
See Brushless Motor.
Electro-Motive Force. Voltage.
The process of transforming a message or data (the "cleartext") into a completely unintelligible form (the "ciphertext"). Only with knowledge of a secret key can the ciphertext be transformed back into the cleartext.
Edison Screw. A screw-fitting lamp base. Several sizes are in common use. See Types of bulb in the Wiki.
Electrostatic Discharge. Static caused by friction such as shoes on a carpet, and particularly noticeable in conditions of low humidity. Even if not perceptible, it can damage sensitive electronic components.
A family of networking protocols defining several methods by which packets of data can be transmitted across a computer network.
The unit of capacitance. See Capacitors in the Wiki.
|Ferrite rod aerial||
A type of aerial used for medium and long wave reception and consisting of a rod or block of ferrite (a magnetic but insulating material) with one or more coils of wire wound around it. See How radios work in the wiki.
|Field Effect Transistor||
A type of transistor where the current flowing between two of its terminals (the source and the drain) is controlled by an electric field created by a voltage on a third terminal (the gate). See Transistors in the Wiki.
A type of light bulb containing a thin wire which glows white hot when a current is passed through it. See Types of bulb in the Wiki.
That part of an operating system which manages a disk and presents it to the users as individual named files, without the users having to be concerned about where on disk their data is actually stored.
A term used for a type of memory that can only be changed by erasing and rewriting a substantial block of cells at a time. Flashing is used as a verb for the process of rewriting or updating such a memory.
A liquid or paste which helps to remove oxide or other deposits in order to make good solder joints. Only usually needed for challenging soldering jobs such as surface mount as solder normally contains a core of flux.
|Full wave rectifier|
A thin piece of low melting point wire designed to melt and so break the circuit if too much current flows due to a fault.
A billion Hz
When two pieces of audio equipment are connected together, each having its own earth connection, some of the small current that should be going from one of the pieces of equipment to its own earth connection instead goes via the connection to the other equipment's earth, causing an objectionable hum in the audio output.
Graphical User Interface. Pronounced "goo-ey" A user interface operated principally using a graphical display and a mouse or other pointing device, as opposed to a Character User Interface.
Globally Unique IDentifier. A 128 bit number used for identifying various types of resource in a computer system.
|Half wave rectifier|
When a current flows through a conductor and a magnetic field is applied to the conductor at right angles, the current tends to be pushed to one side of the conductor, at right angles to the magnetic field. This is the Hall Effect. Used in a Hall effect device to detect or measure a magnetic field, for example in smartphones to detect the earth's magnetic field to implement a compass.
A computer's main long term storage, which is held on rapidly spinning magnetic disk.
The physical electronic and electromechanical parts which comprise a computer.
See Hard Disk
A piece of metal designed to conduct heat away from a component so as to prevent it getting too hot. When soldering, a pair of pliers can be applied to a lead of a sensitive electronic component as a heat sink to prevent the heat of the solder from damaging the component.
The unit of inductance. See Inductors in the Wiki.
The measure of frequency.
A number system based on only 16 digits which are represented by 0-9 and A - F. This is useful because each hexadecimal digit can represent 4 bits and 2 hexadecimal digits can represent 8 bits or a byte.
The lack of an electron in a crystal lattice where there should be one. This leaves behind a positive charge. An electron from an adjacent atom can move into the hole causing the hole to move to the adjacent atom. In this way, holes can act like positively charged particles and carry an electric current.
Integrated Circuit. A circuit comprising anything from dozens to billions of electronic components, all fabricated on a single silicon chip. See Integrated Circuits in the Wiki.
A material which doesn't conduct electricity, such as plastic, wood, glass and fresh air.
A positively or negatively charged atom.
The type of plug (and its socket) familiar as a headphone plug.
A measure of energy, being the amount of work done by 1 watt in 1 second. 4.2 Joules are equivalent to 1 calorie of heat.
Kilobyte: 1024 bytes.
The core of an operating system, which concerns itself with managing the hardware resources at the lowest level. It normally has no user interface, this being provided by another program or programs referred to as the shell. Think of a nut. The shell is what you see but the goodness is inside in the kernel.
A type of malware which logs your keystrokes (including passwords, credit card numbers etc.) and sends them back to its creator, or stores them for him/her to collect later.
Local Area Network. A computer network covering a limited area such as a single building, or at most, a campus.
Liquid Crystal Display. The type of display used in most calculators, phones, tablets and computer monitors, which uses a special liquid which acts on polarised light under an electric field.
Light Dependant Resistor. A device having a high resistance in the dark but whose resistance falls with increasing illumination.
Light Emitting Diode.
A circuit often in the form of an IC which produces a constant well defined voltage from a variable or poorly defined higher voltage input, simply by absorbing excess and turning it into heat. See Linear Power Supplies in the Wiki.
A device for measuring a force and presenting it as an electrical signal. See Digital weighing scales in the wiki.
A magnifying glass, generally without a handle.
The device which produces the microwaves in a microwave oven.
Any bad piece of software which attempts to get onto your computer for malicious purposes.
Master Boot Record. The name given to an older method of organising the contents of a disk. SeeMBR vs GPT disk layoutin the wiki.
A million Hz
The process of impressing an audio or TV signal (for example) an RF signal for transmission.
Metal Oxide Varistor. The commonest type of varistor. See Varistor.
Mean Time Between Failures. A measure of the reliability of an item, most usually measured in hours.
An electrical test instrument which measures voltage, current, resistance and often several other things. Most usually they have a digital readout but analogue ones with a dial are also available.
A number system based on only 8 digits 0 - 7. This is useful because each octal digit can represent 3 bits.
Original Equipment Manufacturer. A somewhat confising term generally meaning a company which sells another company's manufactured goods under its own branding and with its own warranty. Also used of software, for a licence allowing a computer manufacturer to install the software on systems they build.(In fact, the manufacturer could be you, building a computer from standard parts.)
A bit like friction, the unit of resistance to flow of electricity. See Electric circuits, volts amps watts and ohms in the Wiki.
The amount of current (Amps) flowing in a circuit is the pressure (Volts) divided by the resistance (Ohms), or I = V / R.
Organic Light Emitting Diode. A light emitting diode using an organic (i.e. carbon-based chemical) semiconductor rather than one based on inorganic materials such as silicon or a compound of gallium. Also used to refer to a display made up of many OLEDs.
Electricity likes to go all the way round a circuit and back to where it started. When there is a break in the circuit preventing the current from flowing (maybe due to a fault) this is termed an open circuit.
The software which manages the computing, storage and communications resources of a computer, and presents a user interface allowing the user to run and interact with programs as desired.
A device for producing a graphical representation of how an electrical signal varies with time.
In hacker parlance, to gain full control of a device or computer through subversive means. See also Pwn.
Semiconductor material doped with an impurity whose atoms have one too few electrons to match the crystal lattice. These result in holes which can effectively carry an electric current as positive charges.
Personal Area Network. A computer network linking a single person's devices, typically covering, at most, a single room.
A subdivision of a disk. Under the control of the operating system, a disk can be sliced up like a cake into several partitions, each partition being dedicated to a particular purpose. Otherwise, you would have to install another physical disk for each purpose.
A program or app which stores all your passwords in an encrypted vault under a (hopefully) strong master password. This make it possible to use very strong totally random and unguessable passwords, which most password managers will generate for you.
Portable Appliance Test. This is a basic electrical safety test which should be applied to alll mains operated electrical equipment before and after attempting a repair. It comprises a visual inspection and an automated test. See PAT testing in the Wiki.
A thermo-electric effect by which a junction between two different conductors or semiconductors warms if a current is passed through it in one direction and cools if it is passed in the opposite direction. The converse of the Seebeck effect. Used for cooling in mini fridges.
A type of cross-head screw or screwdriver, similar to but not quite the same as Posidriv.
The criminal practice of sending emails or messages through social media inviting the recipient to open a malicious attachment or visit a malicious website.
A light-sensitive transistor used for sensing light.
The property of some materials to develop a voltage across two opposite faces when a physical force is applied, or to stretch or squeeze slightly if a voltage is applied. Pronounced "pie-eezo" by some and "pee-zo" by others. The Oxford Dictionary allows either, but wars have been started over less contentious issues. Used in some microphones and earpieces, quartz crystal frequency standards, and gas lighters.
An individual picture element, or coloured (or black and white) dot, thousands or millions of which make up a digital image.
A type of cross-head screw or screwdriver, similar to but not quite the same as Phillips.
|Potentiometer (or Pot)|
Personal Protective Equipment. Equipment such as safety glasses, dust and fumes extractors, respirators, ear plugs, protective clothing etc. used for protection against health and safety hazards.
A single-use battery.
Potentially Unwanted Program. Any useless but generally (though not necessarily) harmless program, generally installed by the computer vendor, or (knowingly or unknowingly) installed along with downloaded software, the main purpose of which is generally to sell you some other software which you probably don't want.
In hacker parlance, to comprehensively "own" a device or computer. The term derives from a mis-typing of "own" in a video game in the 1990's.
A quantum bit which can be in two different states simultaneously. We have never seen one of these at a Restart Party, and if we ever do we will probably be undecided about what to do with it.
Random Access Memory. Very fast memory used by a computer as working store for data and programs currently being processed.
Malware which encrypts all your files then demands a ransom in order to recover them for you.
A sealed glass tube containing two magnetic contacts forming a switch. The switch can be closed by bringing a magnet near or by energising an electromagnet. Used as the switch in a reed relay or with a magnet attached to a moving part to detect when a cover is closed, a printer paper drawer is fully inserted, or a float in a tank is indicating the tank is full, etc.
A device consisting of a switch or bank of switches operated by an electromagnet. The switch(es) may be simple switch contacts or a reed switch.
An electronic component which resists the flow of electricity. It's resistance is measured in Ohms. A resistor always generates heat, even if only a tiny amount, and any replacement must be rated in Watts accordingly. See Resistors in the Wiki.
Radio Frequency. A high frequency capable of being transmitted as a radio signal.
Root Mean Square. Since AC is continually varying it can't be measured as a unique voltage. The RMS value (a mathematical construct) is the DC voltage that would deliver the same power into a given load.
Read-only memory. Fixed memory which rarely needs to be changed, used for the most basic and lowest level functions in a computer.
An especially pernicious type of malware which subverts the operating system in order to expunge all references to itself and associated malware in listings of files and running programs etc., so as to mask its presence and hinder its removal.
A kind of software "padded cell" in which untested or untrusted software can be tried out without risk to the host computer.
Another name for a Circuit Diagram.
Silicon Controlled Rectifier. See Thyristor.
A rechargeable battery.
A material such as silicon, germanium or gallium arsenide which can be made to conduct electricity either by negatively charged electrons (N-type) or by positively charged holes (P-type), by adding small amounts of carefully chosen impurities.
The smallest block of data a disk can read or write. On older disks this was normally 512 bytes but in modern disks and SSDs it is usually 4096 bytes.
A thermo-electric effect by which a voltage is generated by a junction between two different conductors or semiconductors if it is heated or cooled relative to the rest of the circuit. The converse of the Peltier effect. Used by space craft venturing to the outer reaches of the solar system to generate electricity from a radioactive heat source such as a lump of plutonium.
A program which offers a user interface to lower level parts of an operating system (referred to as the kernel), which lack a user interface. The Mac or Linux command prompt is referred to as the shell, and the Windows Desktop is Windows' shell.
If two wires are touching which shouldn't the electricity may be able to take a short cut, meeting very little resistance and so allowing too much electricity to flow. This is a Bad Thing and can cause things to get hot or even catch fire.
A type of diode using a metal-semiconductor junction, mainly used in power supplies on account of its ability to operate efficiently at higher frequencies. See switching mode power supplies in the wiki.
The mathematically simplest form of vibration or oscillation, which can be represented by a single frequency only. Exemplified by the motion of a pendulum swinging through a small angle, or the height of a point on a wheel above or below the axle as the wheel turns at a constant speed.
Self-Monitoring, Analysis, and Reporting Technology. A technology built into all modern hard disks and solid state disks by which the device can monitor things like its error rate in order to report back and hopefully give early warning of impending failure.
The step-by-step instructions which tell a computer what to do and how to do it.
A mixture (most often) of tin and copper or tin and lead with a relatively low melting point, making it very convenient for making electrical connections. (Americans call it "sodder", and many electrons have been harmed in discussions as to which is correct. But the Americans are on their own on this one.)
|Solid State Disk||
A faster (though more expensive) alternative to a hard disk for a computer's long term storage.
Software in a human-readable form as created by a developer. Generally, this cannot be directly be understood or run by a computer, but has translated by a special program called a compiler into object code.
Any unwanted email. This may simply be an irritation but often it will be a scam or contain malicious attachments or links.
A type of phishing attack directed at a specific victim who has probably been researched in order to make the attack seem highly plausible.
Photo Voltaic Cell. A device for converting light into electricity, commonly known as a solar cell.
A tool with a thin plastic or metal blade typically used (for example) for inserting into the crack between two halves of a plastic case in order to pry it open.
A type of malware which reports browsing history and other personal information back to its creator without your permission.
See Solid State Disk.
A common design of radio receiver. See Superhet in the Wiki.
A type of motor which, instead of turning continuously, turns by a certain fraction of a revolution and stops every time it is given an electrical pulse. Used, for example, for stepping the paper through a printer as it is being printed. See DC and Universal (AC/DC) Motors in the Wiki.
A method of manufacture in which electronic components are soldered directly onto the surface of a printed circuit board, as opposed to the older through-hole method.
Standard Wire Guage. A set of wire diameters where each gauge is approximately 10% thinner than the previous, for example 16 gauge is 1/16in in diameter and 50 gauge is a thousanth of an inch. Cross sectional area in square millimeters is becoming a more usual measure. See Standard Wire Gauge in Wikipedia.
A circuit which produces a constant well defined voltage from a variable or poorly defined voltage input, by switching the power on and off very rapidly and smoothing the result. See Switching Mode Power Supplies in the Wiki.
Total Harmonic Distortion. A measure of the degree to which an audio system distorts its input, effectively introducing new frequencies into the output.
A paste with a special formulation making it a good conductor of heat, used to improve the transfer of heat from an electronic component to a heat sink.
An electronic component like a resistor but with a resistance which decreases substantially with increasing temperature.
A method of manufacture in which electronic components are attached to a circuit board by passing their leads or pins through holes in the board and soldering them to the board on the other side, as opposed to the more modern surface mount technique which allows much higher component densities.
An electronic component with 3 leads used as a switch. Also known as a Silicon Controlled Rectifier. See Transistors in the Wiki.
A device which transforms energy or a measurement from one form to another, e.g. sound to/from electricity (speakers and microphones), or temperature, light, force etc. to an electrical signal.
Two (or more) coils of wire wound around a magnetic core, used to step a voltage up or down or provide isolation between two circuits. See Transformers in the Wiki.
An electronic component with 3 leads used to amplify a signal or switch a current on or off. See Transistors in the Wiki.
A means by which an operating system can tell an SSD about files that have been deleted. This is important for performance reasons related to the way an SSD works. See SSD Migration and Troubleshooting in the wiki.
A type of security screw or screwdriver with a 6-pointed star shape.
|Two Factor Authentication||
A login scheme where you are required to supply not only a password ("something you know") but also prove your possession of a token of some sort ("something you have") or provide a biometric such as a fingerprint ("something you are").
|Two Step Authentication||
A kind of "poor man's Two factor Authentication" where the second factor is a one time code delivered to you by text message. Whilst considerably better than a password on its own, this is no longer greatly recommended on account of the relative ease by which a determined criminal could get a SIM card registered to your phone number and so get the one time code.
Unified Extensible Firmware Interface. A program built in to newer PCs (since around 2011) which controls the PC prior to booting and initiates the boot process. (Older computers used BIOS). See BIOS vs UEFI in the Wiki.
An amplifying device consisting of a glass tube containing several electrodes in a vacuum. An electrically heated cathode emits electrons which are attracted by an anode. Their flow is controlled by the voltage on a wire mesh grid in their path. Long since superseded by much smaller and less power-hungry transistors in all but a few niche applications. Also known as a thermionic valve or vacuum tube.
A device which has a very high resistance until a certain [#Volt|voltage]] is reached, whereupon its resistance falls sharply. Used for absorbing transient voltage surges in a mains supply.
Voltage Dependant Resistor. See Varistor.
A term commonly used for any type of malware, but strictly meaning self-replicating malware.
The unit of electrical pressure, a bit like water pressure. See Electric circuits, volts amps watts and ohms in the Wiki.
A flaw in a website or software product by which it can be compromised for malicious purposes, such as spreading malware.
Wide Area Network. A computer network spanning a substantial geographical area
The unit of power, calculated by multiplying the Volts by the Amps. See Electric circuits, volts amps watts and ohms in the Wiki.
The distance between successive crests of a radio wave as it travels through the air. See Freqvency vs wavelength in the Wiki.
A family of wireless local area networking protocols, allowing a number of computers and other devices within a reasonably confined space to talk to each other.
A type of malware able to spread across a network, or the whole Internet.
An obsolete Windows operating system first released in 2001. Extended support ended in 2014 and remaining users are strongly advised to migrate to a supported operating system as security patches are no longer provided.
A type of aerial commonly used for terrestrial television reception, and consisting of an array of parallel rods, the array pointing in the direction of the transmitter.
A type of diode which starts conducting in the reverse (normally non-conducting) direction at a well defined voltage.
A vulnerability that is discovered (and very often exploited) before any fix is available. Also known as an 0-Day (pronounced "oh-day").