From Quiz Revision Notes


History of Computing


Joseph Jacquard created a punch-card programmable loom which greatly simplified the weaving process.


The Analytical Engine was a proposed mechanical general-purpose computer designed by English mathematician and computer pioneer Charles Babbage. It was first described in 1837 as the successor to Babbage's Difference Engine.


Ada Lovelace, the daughter of Lord Byron, worked closely with Charles Babbage. She wrote a plan for how the Bernoulli numbers might be calculated, which is widely regarded as the first computer program.


Alan Turing invented the Turing Machine, a mathematical model of computation describing an abstract machine that manipulates symbols on a strip of tape according to a table of rules. Computers to this day emulate this functionality of reading simple binary input and computing a logical output. This relatively simple machine enables the computation of any algorithm.


The Colossus machines were electronic computing devices used by British codebreakers to read encrypted German messages during World War II. These were the world's first programmable, digital, electronic, computing devices. They used vacuum tubes (thermionic valves) to perform the calculations. Colossus was designed by engineer Tommy Flowers


ENIAC (Electronic Numerical Integrator and Computer) was the first general-purpose electronic computer. It was designed for the US Army.


William Shockley of Bell Labs invented the first transistor.


EDSAC (Electronic Delay Storage Automatic Calculator) was constructed by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory. Later the project was supported by J. Lyons & Co. Ltd., who were rewarded with the first commercially applied computer, LEO I (Lyons Electronic Office I), based on the EDSAC design.


Ferranti Mark I was the world's first commercially available general-purpose electronic computer. The first machine was delivered to the University of Manchester in February 1951, just ahead of the UNIVAC (Universal Automatic Computer) which was delivered to the United States Census Bureau a month later.


Jack Kilby and Robert Noyce created the first integrated circuit, commonly known as a microchip. An integrated circuit consists of electronic circuits mounted onto a semiconductor.


The CDC 6600 was manufactured by Control Data Corporation. Generally considered to be the first successful supercomputer, it was designed by Seymour Cray.


Douglas Engelbart invented the computer mouse. It was built of a wooden case with two wheels and a button on top.


ARPANET was the first wide-area packet-switched network with distributed control. It was the precursor to the Internet.


Intel released the first microprocessor, the 4-bit Intel 4004.


Email was invented by Ray Tomlinson.


The term “Internet” was first used.


Microsoft was founded by Bill Gates and Paul Allen, to develop and sell BASIC interpreters for the Altair 8800.


Apple-1 was released. It was an 8-bit computer designed by Steve Wozniak. To finance its creation, Steve Jobs sold his Volkswagen Bus, and Wozniak sold his HP-65 calculator. Production was discontinued in September 1977 after the introduction of its successor, the Apple II.


IBM launched its first personal computer, the IBM Model-5150.


Sinclair ZX spectrum was released.


Apple Mac was released.


Microsoft released its first version of the Windows operating system.


The World Wide Web was created by Tim Berners-Lee.


Microsoft Office was released.


Java programming language was developed by James Gosling of Sun Microsystems.


Google was founded by Larry Page and Sergey Brin while they were PhD students at Stanford University.


The first quantum computer was created.


Raspberry Pi single-board computer was released at a cost of £35. By December 2019, a total of 30 million devices had been sold. It was designed for the teaching of basic computer science in schools but has also been used in commercial applications.

Personal Computers

Altair 8800 was the first commercially successful personal computer. It was advertised on the cover of Popular Electronics in January 1975 and was sold by mail order. It was designed by MITS (Micro Instrumentation and Telemetry Systems) and was based on the Intel 8080 processor.

Commodore PET was released in 1977 by Commodore International. It contained an 8-bit microprocessor and included a version of BASIC in read-only memory. PET was a backronym of Personal Electronic Transactor. 219,000 units were sold.

IBM Personal Computer (model 5150, commonly known as the IBM PC) was the first microcomputer released in the IBM PC model line. Based on the Intel 8088 microprocessor. The operating system was IBM PC DOS, developed by Microsoft. The starting price was US$1,565 (equivalent to $5,040 in 2022).

Osborne 1 was the first commercially successful portable computer. It was released in 1981 and weighed 11 kg. The microprocessor was a Zilog Z80 and the operating system was CP/M.

BBC Micro was a series of microcomputers designed and built in the 1980s by Acorn Computers, headed by Hermann Hauser and Chris Curry, for the BBC Computer Literacy Project. The CPU was an 8-bit MOS Technology 6502 and the programming language was BBC BASIC. An accompanying 1982 television series, The Computer Programme, featuring Chris Serle learning to use the machine, was broadcast on BBC2.

ZX Spectrum was developed by Sinclair Research and was Britain's best-selling microcomputer, selling 5 million units. The initial cost of the 16 KB machine was £125. It was the successor to the ZX80 and ZX81 machines. The original ZX Spectrum had a rubber keyboard. The microprocessor was an 8-bit Z80. Sinclair licensed the Spectrum design to Timex Corporation in the United States.

Commodore 64 was an 8-bit computer released in 1982. It was the highest-selling single computer model of all time, with estimates placing the number sold between 12.5 and 17 million units. The machine took its name from its 64 kilobytes of RAM.

Operating Systems

CP/M (Control Program for Microcomputers) was created in 1974 for Intel 8080/85-based microcomputers by Gary Kildall of Digital Research, Inc. It was widely used in business through the late 1970s and into the mid-1980s but was eventually displaced by DOS following the 1981 introduction of the IBM PC.

MS-DOS (Microsoft Disk Operating System) is an operating system for x86-based personal computers. IBM PC DOS is a rebranded version of MS-DOS. In 1980 IBM approached Digital Research, at Bill Gates' suggestion, to license a forthcoming version of CP/M for its new product, the IBM Personal Computer. Upon the failure to obtain a signed non-disclosure agreement, the talks failed, and IBM instead contracted with Microsoft to provide an operating system. The resulting product, MS-DOS, soon began outselling CP/M.

Microsoft Windows is the most popular desktop operating system in the world, with a 70% market share.

List of Microsoft Windows versions

Version Release date
Windows 1.0 1985
Windows 2.0 1987
Windows 2.1x 1988
Windows 3.0 1990
Windows 3.1 1992
Windows NT 3.1 1993
Windows 3.2 1993
Windows NT 3.5 1994
Windows NT 3.51 1995
Windows 95 1995
Windows NT 4.0 1995
Windows 98 1998
Windows 2000 2000
Windows ME 2000
Windows XP 2001
Windows XP Professional x64 Edition 2005
Windows Vista 2007
Windows 7 2009
Windows 8 2012
Windows 8.1 2013
Windows 10 2015
Windows 11 2021

Windows 1.0 replaced MS-DOS.

Windows NT is a multiprocessing and multi-user operating system.

Windows 95 introduced the Start menu. The Windows 95 release included a commercial featuring The Rolling Stones' 1981 single "Start Me Up" (a reference to the Start button). Microsoft paid the Rolling Stones $3 million for the rights to “Start Me Up”. Windows 95 was bundled as a standalone operating system that did not require a separate DOS license.

Windows ME (Millennium Edition) became infamously known by many as one of the worst versions of Windows ever released, mainly due to stability problems.

Windows Vista received poor reviews, mainly for its much higher hardware requirements and perceived slowness compared to Windows XP.

Windows 8 received a mostly negative reception. The new user interface of the operating system was widely criticized for being confusing and unintuitive.

Windows 10 reintroduced the Start menu, and incorporated Microsoft's intelligent personal assistant, Cortana. Internet Explorer was replaced with Microsoft Edge.

Mac OS was developed for the Macintosh family of personal computers from 1984 to 2001, starting with System 1 and ending with Mac OS 9. The Macintosh operating system is credited with having popularized the graphical user interface concept.

macOS succeeded the classic Mac OS. In 1985 Apple cofounder Steve Jobs had left Apple and started another company, NeXT, developing the NeXTSTEP platform that would later be acquired by Apple to form the basis of macOS.

List of macOS versions

Version Release name Release date
Mac OS X 10.0 Cheetah 2001
Mac OS X 10.1 Puma 2001
Mac OS X 10.2 Jaguar 2002
Mac OS X 10.3 Panther 2003
Mac OS X 10.4 Tiger 2005
Mac OS X 10.5 Leopard 2007
Mac OS X 10.6 Snow Leopard 2009
Mac OS X 10.7 Lion 2011
Mac OS X 10.8 Mountain Lion 2012
Mac OS X 10.9 Mavericks 2013
Mac OS X 10.10 Yosemite 2014
Mac OS X 10.11 El Capitan 2015
macOS 10.12 Sierra 2016
macOS 10.13 High Sierra 2017
macOS 10.14 Mojave 2018
macOS 10.15 Catalina 2019
macOS 11 Big Sur 2020
macOS 12 Monterey 2021
macOS 13 Ventura 2022
macOS 14 Sonoma Announced on 5 June 2023

Unix is a family of multi-user computer operating systems that derive from the original AT&T Unix, whose development was started in 1969 at the Bell Labs research centre by Kenneth Thompson and Dennis Ritchie.

Almost the entire operating system is written in the C programming language.

Linux is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released in 1991 by Finnish-American software engineer Linus Torvalds.

Popular Linux distributions include Debian, Fedora Linux, and Ubuntu. Commercial distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise.

Tux is the penguin mascot of the Linux kernel, and is based on an image created by Larry Ewing in 1996.

ChromeOS is a Linux-based operating system developed and designed by Google. Laptops or tablets running ChromeOS are known as Chromebooks.

Programming languages

FORTRAN (Formula Translation) was originally developed by IBM in the 1950s for scientific and engineering applications, and subsequently came to dominate scientific computing.

COBOL was designed in 1959 by CODASYL and was partly based on the programming language FLOW-MATIC designed by Grace Hopper. It was created as part of a US Department of Defense effort to create a portable programming language for data processing. It is primarily used in business, finance, and administrative systems.

BASIC (Beginners' All-purpose Symbolic Instruction Code) was created by John Kemeny and Thomas Kurtz at Dartmouth College in 1963. It became the de facto programming language for home computer systems that usually had a BASIC interpreter installed by default.

Pascal is a procedural programming language, designed by Niklaus Wirth and intended to encourage good programming practices using structured programming and data structuring. It is based on the ALGOL 60 language.

Ada is an object-oriented high-level programming language designed for the United States Department of Defense (DoD). Ada was named after Ada Lovelace.

C was developed by Dennis Ritchie between 1969 and 1973 at AT&T Bell Labs to construct utilities running on Unix. C is widely used for systems programming in implementing operating systems and embedded system applications.

C++ was developed by Bjarne Stroustrup starting in 1979 at Bell Labs. It is as an extension of the C programming language and has object-oriented features.

C# is based on the C family of languages, and has similarities to C, C++, Java, and JavaScript. It was designed by Anders Hejlsberg from Microsoft in 2000.

Java is a high-level, object-oriented programming language used to create complete applications. The language is platform independent, allowing it to run on any device that supports its environment. Java was originally developed by James Gosling as a core component of Sun Microsystems' Java platform. The Java logo is a cup of coffee, and the mascot is a cartoon character named Duke.

Python is a general-purpose programming language created by Dutch programmer Guido van Rossum and first released in 1991. Python's name is derived from the British comedy troupe Monty Python.

Ruby was developed by Yukihiro "Matz" Matsumoto in Japan and released in 1995. It was designed with an emphasis on programming productivity and simplicity.

Go is an object-oriented programming language that Google created in 2009 for networking and infrastructure. It has evolved into a general-purpose language used in a wide range of applications.

Kotlin was designed by JetBrains, a company based in Prague. Kotlin is designed to interoperate fully with Java, and is used by Android app developers. The name comes from Kotlin Island, near Saint Petersburg.

R is an open-source programming language for statistical computing and data analysis.

JavaScript is a dynamic scripting language that is one of the core technologies of the World Wide Web. It was designed by Brendan Eich of Netscape and released in 1995.

PHP is a widely-used open source and general-purpose scripting language that is especially suited for web development. PHP’s popularity is owed to the fact that it was one of the first server-side languages that developers could embed into HTML. It was created by Rasmus Lerdorf in 1995. PHP was originally an abbreviation of Personal Home Page, but it now stands for the recursive initialism PHP: Hypertext Preprocessor.

Computer security

Types of attack –

Malware ('malicious software') is any program or file that is harmful to a computer user. Malware can be divided into a number of types –

Virus - replicates itself by modifying other computer programs and inserting its own code into those programs. Once downloaded, opened or executed, the virus can piggyback onto programs to corrupt data.

Worm - a standalone program that replicates itself in order to spread to other computers. Creeper was the first computer worm, while Reaper was the first antivirus software, designed to eliminate Creeper. Reaper was created by Ray Tomlinson in 1972.

Stuxnet is a computer worm discovered in 2010. It initially spread via Microsoft Windows, and targeted Siemens industrial software and equipment. Different variants of Stuxnet targeted five Iranian organizations, with the probable target widely suspected to be uranium enrichment infrastructure in Iran.

Trojan horse - any malware that misleads users of its true intent by disguising itself as a standard program. It is unable to replicate itself.

Ransomware - comprises a class of malware which restricts access to the computer system that it infects, and demands a ransom paid to the creator of the malware in order for the restriction to be removed. Ransomware attacks are typically carried out using a Trojan disguised as a legitimate file that the user is tricked into downloading or opening when it arrives as an email attachment.

Rogue software - a form of malware and internet fraud that misleads users into believing there is a virus on their computer and aims to convince them to pay for a fake malware removal tool that actually installs malware on their computer.

Spyware - malware used to gain access to a user’s systems and monitor their data, files, and behavior. Spyware is frequently associated with advertising.

Terms used in connection with attacks –

Phishing – the fraudulent practice of sending emails purporting to be from reputable companies in order to induce individuals to reveal personal information, such as passwords and credit card numbers.

Smishing – similar to phishing, but the messages are sent via text messages rather than emails.

Vishing – similar to phishing, but the messages are sent via phone calls or voice mails rather than emails. Also known as voice phishing.

Whaling – a type of phishing attack where a particularly important person in an organisation is targeted.

Spoofing – a sort of fraud in which someone forges the sender’s identity and poses as a reputable source in order to obtain personal information, acquire money, spread malware, or steal data.

Doxing – short for "dropping dox," is an online attack in which hackers dig up personal information and documents – hence, the “dox” part of “dropping dox” – to expose the real identities of people hoping to remain anonymous.

Clickjacking – a malicious technique of tricking a user into clicking on something different from what the user perceives, thus potentially revealing confidential information.

Denial of service attack (DoS attack) – a cyber-attack in which the perpetrator seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host connected to a network. In a distributed denial-of-service attack (DDoS attack), the incoming traffic flooding the victim originates from many different sources, and is usually performed by a group of Internet-connected devices known as a botnet (a portmanteau of the words "robot" and "network").


A hacker is able to subvert computer security. If doing so for malicious purposes, the person can also be called a cracker. There are three types of hackers –

Black hat – someone who maliciously searches for and exploits vulnerabilities in computer systems or networks, often using malware and other hacking techniques to do harm.

White hat – a security specialist hired to find vulnerabilities in software, hardware and networks that black hats may find and target. Unlike black hats, white hats only hack networks when legally permitted to do so. Also known as ethical hackers.

Grey hat – someone who exploits security vulnerabilities without malicious intent, like a white hat, but may use illegal methods to find flaws.

Anti-virus software

Norton AntiVirus

Founded by Peter Norton, Norton AntiVirus has been developed and distributed by Symantec since 1990. The product runs on Microsoft Windows, Linux, and macOS.

The current Norton product, Norton 360, was developed by Gen Digital (formerly Symantec Corporation).


John McAfee created VirusScan, the first commercial anti-virus software, in 1987.

In 2000, McAfee/Network Associates was the leading authority in educating and protecting people against the Love Bug or ILOVEYOU virus, one of the most destructive computer viruses in history.

Intel acquired McAfee in 2010.


Bitdefender is a Romanian cybersecurity technology company headquartered in Bucharest. The company was founded in 2001 by the current CEO and main shareholder, Florin Talpes.

Kaspersky Anti-Virus

Kaspersky Lab is a Russian computer security company, co-founded by Natalia Kaspersky and Eugene Kaspersky in 1997, offering anti-virus, anti-spyware, anti-spam, and anti-intrusion products.

In 2016 the software has about 400 million users and had the largest market-share of cybersecurity software vendors in Europe.

The U.S. Department of Homeland Security banned Kaspersky products from all government departments in 2017.

Avast Antivirus

Avast was founded in Prague in 1988. The software is software are sold on a freemium model, where basic security features are free, but more advanced features require purchasing a premium version. The free version is also supported by ads.

In 2017 it had the largest share of the market for antivirus applications.

AVG was a cybersecurity software company founded in 1991 and it merged into Avast following an acquisition in 2017.

Cloud computing

Cloud computing is the on-demand availability of computing resources, such as storage and infrastructure, as services over the internet. The market is currently dominated by Amazon Web Services, Microsoft Azure, and Google Cloud.

iCloud allows users to store data such as music files for download to multiple devices such as iPhones, iPods, iPads, and personal computers running Mac OS X or Microsoft Windows on computer servers owned by Apple

File hosting

A file-hosting service is a hosting service on the internet that stores user data, like images, videos, and other types of data files. These services are secure and allow a user to store their files safely on the internet. Since the files are stored on the internet, they can be accessed from anywhere if the user has internet access.

Microsoft OneDrive is a file hosting service operated by Microsoft. First launched in 2007, it enables registered users to share and synchronize their files. OneDrive also works as the storage backend of the web version of Microsoft Office. OneDrive offers 5 GB of storage space free of charge.

Quantum computing

A quantum computer is a device for computation that makes direct use of quantum mechanical phenomena, such as superposition and entanglement, to perform operations on data. Quantum computers are different from traditional computers based on transistors.

In quantum computing, a qubit or quantum bit is a unit of quantum information.

The field of quantum computing was initiated by the work of Paul Benioff and Yuri Manin in 1980, Richard Feynman in 1982, and David Deutsch in 1985.

IBM Quantum System One was the first commercial quantum computer.

It was hoped that a quantum computer could perform some calculations exponentially faster than any modern "classical" computer, but in 2023 classical computers outperform quantum computers for all real-world applications.

Office productivity software

Word processing

WordPerfect was the dominant player in the word processor market in the 1980s. Following a failed release for Microsoft Windows, Microsoft Word took over the market.

Microsoft Word was first released in 1983 under the name Multi-Tool Word for Xenix systems. Commercial versions of Word are licensed as a standalone product or as a component of Microsoft Office. In the top menu, the icon for the save button is a floppy disk.


VisiCalc (visible calculator) was the first spreadsheet computer program for personal computers, originally released for the Apple II in 1979. When Lotus 1-2-3 was launched in 1983, taking full advantage of the expanded memory and screen of the PC, VisiCalc sales practically ended overnight.

Lotus 1-2-3 was a state-of-the-art spreadsheet and the standard throughout the 1980s. Due to the lack of a graphical user interface Lotus was surpassed by Microsoft in the early 1990s and never recovered.

Microsoft Excel was launched in 1987. Excel was one of the first spreadsheet programs to use a graphical interface with pull down menus. The first version was only released for the Macintosh. It consists of 1048576 rows and 16384 columns, a row and column together make a cell.

Presentation program

Microsoft PowerPoint was created by Forethought, Inc. in 1987, initially for Macintosh computers only. Microsoft acquired PowerPoint three months after it appeared. PowerPoint was originally designed to provide visuals for group presentations within business organisations. PowerPoint's worldwide market share of presentation software is around 95%.

Microsoft Office

Office was first announced by Bill Gates in 1988, at COMDEX in Las Vegas. The first version of Office contained Word, Excel, and PowerPoint. Later versions included an email client (Outlook), a database management system (Access), and a desktop publishing app (Publisher). In Microsoft Office 2007, Calibri replaced Times New Roman as the default typeface in Word and replaced Arial as the default in PowerPoint, Excel, and Outlook. The branding Office 365 was first introduced in 2010 to refer to subscription-based software as a service platform for the corporate market. In October 2022, Microsoft announced that it would rebrand the product as "Microsoft 365".



Acer is a Taiwanese company founded in 1976.

Current models – Aspire, Chromebook, Spin, Swift.


The MacBook Air is Apple's least expensive notebook computer and was released in 2008. The MacBook Pro is Apple's higher-end notebook available in 13-inch, 14-inch, and 16-inch configurations and was released in 2006.

Current models – MacBook Pro, MacBook Air.


Asus is a Taiwanese company founded in 1989.

Current models – Chromebook, Flip, Zenbook.


Lenovo is a Chinese company founded as Legend in 1984, and acquired IBM's personal computer business in 2005, including the ThinkPad laptop. The IdeaPad line of laptops was introduced in 2008. Lenovo has been the world's largest PC vendor by unit sales in every year since 2013, with the exception of 2017.

Current models – IdeaPad.


Dell was founded by Michael Dell in 1984 and is the world's 3rd-largest PC vendor by unit sales. The first Inspiron laptop model was introduced in 1997.

Current models – Inspiron, XPS.


HP Inc. was formerly known as Hewlett-Packard. It is the world's 2nd-largest PC vendor by unit sales.

Current models – Envy, Pavilion, Chromebook, ProBook.


Microsoft Surface is a series of touchscreen-based personal computers, tablets, and interactive whiteboards designed and developed by Microsoft, most of them running the Windows operating system. They are designed to be premium devices.

Current models – Surface.

Tablet computers

A tablet is a mobile device, typically with a mobile operating system and touchscreen display processing circuitry, and a rechargeable battery.

A 2-in-1 PC is a hybrid or combination of a tablet and laptop computer that has features of both. Distinct from tablets, 2-in-1 PCs all have physical keyboards.

A phablet is a mobile device combining or straddling the size formats of smartphones and tablets. The Sony Xperia Z Ultra is a 2013 Android phablet designed and manufactured by Sony Mobile

Market share (2022) – Apple 37%, Samsung 18%, Amazon 11%


The iPad was released in 2010. It features a multi-touch screen and a virtual onscreen keyboard. The iOS operating system was switched to iPadOS in 2019. Total sales exceed 670 million units.

iPad range consists of the original iPad lineup and three other products –

iPad Mini – a smaller tablet with screen sizes of 7.9 inches and 8.3 inches.

iPad Air – uses the Apple M1 chip.

iPad Pro – professional model with a screen size of 12.9 inches. Uses the Apple M2 chip.


The Amazon Fire is built with Quanta Computer in Taiwan. The Kindle Fire was first released in 2011, featuring a colour 7-inch multi-touch and running on Fire OS. In 2014, when the fourth generation was introduced, the name "Kindle" was dropped. In later generations, the Fire tablet is also able to convert into a Smart speaker with interaction by voice command through Alexa.


The Samsung Galaxy Tab is a line of Android OS tablet computers first released in 2010.


ARPANET (Advanced Research Projects Agency Network), created by the Defense Advanced Research Projects Agency (DARPA) of the United States Department of Defense, was the world's first operational packet switching network, and the predecessor of the contemporary global Internet. The packet switching of the ARPANET was based on designs by Lawrence Roberts, of the Lincoln Laboratory.

Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet. The foundational protocols in the suite are the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP).

Vinton Gray ‘Vint’ Cerf is an American Internet pioneer, who is recognized as one of ‘the fathers of the Internet’, sharing this title with Bob Kahn, for the invention of TCP/IP.

The Internet has no single centralized governance in either technological implementation or policies for access and usage; each constituent network sets its own policies. The overarching definitions of the two principal name spaces on the Internet, the Internet Protocol address (IP address) space and the Domain Name System (DNS), are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN).

Country code top-level domain (ccTLD) is an Internet top-level domain generally used or reserved for a country, sovereign state, or dependent territory identified with a country code.

Internet of Things (IoT) is the network of physical objects or "things" embedded with electronics, software, sensors, and network connectivity, which enables these objects to collect and exchange data.

World Wide Web

The World Wide Web, or Web, is an information system on the internet which allows documents to be connected to other documents by hypertext links, enabling the user to search for information by moving from one document to another.

The Web was invented by Tim Berners-Lee at CERN in 1999. He also made the world’s first web browser and web server. The first website built ( was at CERN, and was first put online on 6 August 1991.

HTML (Hyper Text Markup Language) – the publishing format for the web. It includes the ability to format documents and link to other documents and resources.

URL (Uniform Resource Locator) – a kind of 'address' that is unique to each resource on the web. It could be the address of a webpage or an image file.

HTTP (Hypertext Transfer Protocol) – allows HTML documents to be requested and transmitted between browsers and web servers via the internet.

HTTPS (Hypertext Transfer Protocol Secure) – an extension of the Hypertext Transfer Protocol. It uses encryption for secure communication over a computer network, and is widely used on the Internet.

Web browser – a tool that enables users to surf and access websites that are on the internet.

Web server – a computer where files are stored which can be accessed via the internet using HTTP or HTTPS.

Web 2.0 – the current state of the internet that has more user-generated content and usability for end-users than Web 1.0.

Cookie – a small piece of data sent from a website and stored on the user's computer by the user's web browser while the user is browsing.

Website development

LAMP is an acronym for an archetypal model of web service solution stacks, originally consisting of largely interchangeable components:

·          Linux operating system

·          Apache HTTP Server

·          MySQL relational database management system

·          PHP programming language

The ‘P’ in Lamp can also stand for Python or Perl

JavaScript is the dominant client-side scripting language of the Web, with 98% of all websites using it for this purpose. Scripts are embedded in or included from HTML documents. All major web browsers have a built-in JavaScript engine that executes the code on the user's device.

HTML is a markup language that web browsers use to interpret and compose text, images, and other material into visible or audible web pages.

XML (Extensible Markup Language) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data.

CSS (Cascading Style Sheets) is a style sheet language used for describing the presentation of a document written in a markup language such as HTML or XML.

Ruby on Rails is a server-side web application framework written in Ruby.

WordPress is among the most popular content management systems. It is written in PHP.


Adobe Inc. was founded by John Warnock and Charles Geschke in 1982. Products include Adobe Photoshop image editing software, Adobe Illustrator vector-based illustration software, Adobe Acrobat Reader, and the Portable Document Format (PDF) that is based on the PostScript page description language.

ARM was founded as Advanced RISC Machines, ARM, a joint venture between Acorn Computers, Apple Computer and VLSI Technology. Based in Cambridge, its primary business is the design of ARM processors (CPUs). Since 2016, it has been owned by Japanese conglomerate SoftBank Group.

Cisco Systems was founded in 1984 by Leonard Bosack and Sandy Lerner. John Chambers was CEO from 1995 to 2015. Cisco is known particularly for its networking hardware.

Compaq was founded in 1982 and rose to become the largest supplier of PC systems during the 1990s before being overtaken by Dell in 2001. The company was acquired for US$25 billion by HP in 2002. The brand remained in use by HP for lower-end systems until 2013 when it was discontinued.

Hewlett-Packard (HP) was founded in 1939 by Bill Hewlett and David Packard. HP was the world's leading PC manufacturer from 2007 until 2013, when Lenovo moved ahead of HP. In 2015 the former Hewlett-Packard Company changed its name to HP Inc. and Hewlett Packard Enterprise was spun off as a newly created company.

Intel (From integrated and electronics) was founded in 1968. It is one of the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 series of instruction sets found in most personal computers.

The Intel 4004 chip was released by Intel in 1971. It was the first commercially available microprocessor by Intel.

The x86 family is based on the Intel 8086 microprocessor.

International Business Machines Corporation (IBM) was founded in 1911 as the Computing-Tabulating-Recording Company. During the 1960s and 1970s, the IBM mainframe, exemplified by the System/360, was the dominant computing platform, and the company produced 80 percent of computers in the U.S. and 70 percent of computers worldwide. After pioneering the multipurpose microcomputer in the 1980s, IBM began losing its market dominance to emerging competitors.

IBM is one of 30 companies in the Dow Jones Industrial Average.

Infosys is headquartered in Bangalore. Infosys is the second-largest Indian IT company, after Tata Consultancy Services.

Logitech was founded in Switzerland in 1981. Products include keyboards, mice, tablet accessories, headphones and headsets, webcams, and Bluetooth speakers. In 2008, Logitech announced that it had manufactured one billion computer mice since 1985.

Oracle Corporation was founded in Redwood City, California and is now headquartered in Austin, Texas. Larry Ellison, a co-founder of Oracle, has served as Oracle's CEO since its founding in 1977. In 2020, Oracle was the third-largest software company in the world by revenue and market capitalization. The Oracle relational database management system (RDBMS) uses the Structured Query Language (SQL).

SAP is a German software company founded in 1972. It is the world's leading enterprise resource planning (ERP) software vendor and the largest non-American software company by revenue.

Tata Consultancy Services (TCS) was founded in 1968 and is part of the Tata Group. TCS is the second largest Indian company by market capitalization.

VMWare develops virtualization software, that creates an abstraction layer over computer hardware that allows the hardware elements of a single computer to be divided into multiple virtual computers, commonly called virtual machines (VMs).

Networks and Mobile Phones

Cellular Networks

A Cellular network or Mobile network is a radio network distributed over land areas called cells, each served by at least one fixed-location transceiver, known as a cell site or base station. In a cellular network, each cell uses a different set of frequencies from neighboring cells, to avoid interference and provide guaranteed bandwidth within each cell.

There are five generations of cellular networking technology –

1G - the first commercial cellular network was launched in Japan by Nippon Telegraph and Telephone in 1979. 1G was introduced to the USA in 1983.

2G - launched on the Global System for Mobile Communications (GSM) in Finland in 1991. It provided significant mobile talk advancements, introducing encrypted calls. While radio signals on 1G networks are analog, radio signals on 2G networks are digital. The first SMS text message was sent from a computer to a mobile phone in 1992 in the UK, while the first person-to-person SMS from phone to phone was sent in Finland in 1993.

3G - launched in 2001, 3G offered better voice quality and faster data transfer, allowing users to surf the internet and stream music on a mobile phone. Universal Mobile Telecommunications System (UMTS) is a third-generation mobile cellular system for networks based on the GSM standard.

4G - the first 4G networks were commercially deployed in Norway and Sweden in 2009, and have since been deployed throughout most parts of the world. Starting at a minimum of 12.5 Mbps, 4G provided high-quality video streaming/chat, fast mobile web access, HD videos, and online gaming. 4G has speeds of up to 150 Mbit/s download.

5G - cellular phone companies began deploying worldwide in 2019. 5G has higher bandwidth to deliver faster speeds than 4G and can thus connect more different devices. 5G is capable of delivering significantly faster data rates than 4G, with peak data rates of up to 20 gigabits per second (Gbps).

Wi-Fi Networks

Wi-Fi stands for Wireless Fidelity. It is used to create a wireless network of devices to access the internet. It follows IEEE 802.11 standards. Wi-Fi networks use multiple bands of radio waves and microwaves to transmit data among the devices wirelessly. In WiFi networks, Internet service is accessible only where a WiFi connection is present.

The current generation wireless standard is Wi-Fi 6.

Mobile phones


The first hand-held cell phone was demonstrated by John F. Mitchell and Dr. Martin Cooper of Motorola in 1973, using a handset weighing around 2kg. In 1983, the DynaTAC 8000x was the first to be commercially available. From 1983 to 2014, worldwide mobile phone subscriptions grew from zero to over 7 billion.

It was claimed that Ernie Wise made the first mobile phone call in the UK on 1 January 1985 from St Katharine Docks, East London, to Vodafone's Headquarters in Newbury.

The first SIM (Subscriber Identity Module) card was made in 1991 by Munich smart card maker Giesecke & Devrient.

The first Short Message Service (SMS) text message was sent from a computer to a mobile phone in 1992 in the UK while the first person-to-person SMS from phone to phone was sent in Finland in 1993.

Symbian was an operating system used in Nokia phones. It was the most popular smartphone operating system on a worldwide average until the end of 2010, when it was overtaken by Android.

Android is developed by a consortium of developers known as the Open Handset Alliance, though its most widely used version is primarily developed by Google. It was unveiled in 2007, with the first commercial Android device, the HTC Dream, being launched in 2008.



The first-generation iPhone was released in June 2007. It incorporated a 3.5-inch multi-touch display and had a starting price of US$499.

The iPhone 3G was released in 2008 and introduced faster 3G connectivity, and a lower starting price of US$199.

The iPhone 4 was marketed as the "world's thinnest smartphone" and introduced the Retina display.

The iPhone 4s was announced in 2011 and introduced the Siri virtual assistant.

The iPhone 5s introduced the Touch ID fingerprint authentication sensor.

The iPhone 14 and iPhone 14 Plus are the sixteenth and latest generation of iPhones, and were announced during Apple Event, Apple Park in Cupertino, California, in September 2022. The price of the iPhone 14 starts at $799.

The iPhone runs on the iOS operating system. Major versions of iOS are released annually. The current stable version, iOS 16, was released in September 2022.

The iPhone accounts for around 16% of global smartphone market share.


The line of BlackBerry smartphones was developed and maintained by the Canadian company BlackBerry Limited (formerly known as Research In Motion, or RIM) from 1999 to 2016, after which it was licensed to various companies. The company was founded by Mike Lazaridis.

The phones were known for having a physical QWERTY keyboard.

At its peak in 2011, there were 85 million BlackBerry subscribers worldwide, but the rise of Google's Android platform and Apple's iOS caused it to decline in popularity by nearly three-quarters.

BlackBerry phones are now officially defunct and are unable to function.


The Nexus line of Android phones started out in 2010 and reached its end in 2016, replaced by Google Pixel.

The current models in the Pixel line are the Pixel 7 and Pixel 7 Pro.


Huawei was founded in 1987 by Ren Zhengfei and is headquartered in Shenzhen.

Their portfolio of phones includes both high-end smartphones, its Huawei Mate series and Huawei P series, and cheaper handsets that fall under its Honor brand.

Huawei is currently banned from doing business with US companies as the US government considers Huawei to be a national security threat.


Motorola MicroTAC is a cellular phone first manufactured as an analog version in 1989. The MicroTAC introduced a new "flip" design, where the "mouthpiece" folded over the keypad. This set the standard and became the model for modern flip phones today. Its predecessor was the much larger Motorola DynaTAC and it was succeeded by the Motorola StarTAC in 1996.


Nokia made significant contributions to the mobile telephony industry, assisting in the development of the GSM, 3G, and LTE standards. For a decade beginning in 1998, Nokia was the largest worldwide vendor of mobile phones and smartphones. In the later 2000s, however, Nokia suffered from a series of poor management decisions, and soon saw its share of the mobile phone market drop sharply.

Nokia 5110 is a GSM mobile phone that was introduced in 1998.

Nokia 3210 is a GSM cellular phone, announced by Nokia in 1999.

Nokia introduced its “Connecting People” advertising slogan in 1992.


Oppo phones are smartphones produced by the partially state-owned Chinese company Oppo.

The current lineup of phones includes the Find X, N, and Reno series.


The Samsung Galaxy was released in 2009. It uses the Android operating system.

The Galaxy S was released in 2010. It is produced in over two dozen variations, and 25 million units were sold by 2013.

Samsung later expanded the Galaxy S line to tablet computers with the announcement of the Galaxy Tab S in 2014.

In 2012, Samsung Electronics became the world's largest mobile phone maker by unit sales, overtaking Nokia. The Galaxy accounts for around 19% of global smartphone market share today.

In 2017, Samsung announced the voice-powered digital assistant named "Bixby". It was introduced alongside the Samsung Galaxy S8.

Samsung announced the Samsung Galaxy S23 series, consisting of the Samsung Galaxy S23, Samsung Galaxy S23+ and Samsung Galaxy S23 Ultra, in February 2023.


The Sony Xperia X1 was the first smartphone to be released by Sony, in 2008.

Sony Mobile was previously known globally as Sony Ericsson before being rebranded in 2012.

The X10 was released in 2010. It was the first in the Xperia line to feature the Android operating system, where previous models ran on the Windows Mobile OS.

In 2017, Sony Mobile held less than 1% global market share.


Xiaomi released its first smartphone in 2011. Most of the phones run on the MIUI User interface, which is based on the Android operating system.

Xiaomi's flagship mobile handset line is the Xiaomi series (formerly known as Mi series).

List of Android versions

Version Internal codename Release date
Android 1.0 2008
Android Cupcake Cupcake 2009
Android Donut Donut 2009
Android Eclair Eclair 2009
Android Froyo Froyo 2010
Android Gingerbread Gingerbread 2010
Android Honeycomb Honeycomb 2011
Android Ice Cream Sandwich Ice Cream Sandwich 2011
Android Jelly Bean Jelly Bean 2012
Android KitKat Key Lime Pie 2013
Android Lollipop Lemon Meringue Pie 2014
Android Marshmallow Macadamia Nut Cookie 2015
Android Nougat New York Cheesecake 2016
Android Oreo Oatmeal Cookie 2017
Android Pie Pistachio Ice Cream 2018
Android 10 Quince Tart 2019
Android 11 Red Velvet Cake 2020
Android 12 Show Cone 2021
Android 13 Tiramisu 2022
Android 14 Upside Down Cake Q3 2023
Android 15 Vanilla Ice Cream 2024

Mobile Network Operators

O2 was formed in 1985 as Cellnet and was later rebranded as BT Cellnet. O2 was bought by Telefonica in 2005 for £18 billion, but retained its name and continued to be based in the United Kingdom.

Orange S. A. was created when Hutchison Whampoa acquired a controlling stake in Microtel Communications Ltd during the early-1990s and rebranded it Orange. It became a subsidiary of Mannesmann in 1999 and was acquired by France Telecom in 2000. The France Telecom company was rebranded to Orange in 2013.

T-Mobile was launched as Mercury One2One (stylised one2one) in 1993. one2one was purchased by Deutsche Telekom in 1999. In 2010, it merged with Orange UK to form a joint venture, Everything Everywhere, which continued to operate the T-Mobile and Orange brands until 2015.

Virgin Mobile is owned by Virgin Media which is part of Virgin Media O2. was launched in 1999 as a private joint venture between One2One (later T-Mobile UK) and the Virgin Group. Virgin Media O2 is the biggest mobile network in the UK with around 24 million mobile customers.

Three UK (officially Hutchison 3G UK Limited) launched as the UK's first commercial video mobile network on 3 March 2003 (03-03-03), the day that 3G services went live across the country. In June 2023 it was announced that Three UK and Vodafone were planning to merge their UK-based operations.

EE is a brand within the BT Group. EE is the largest mobile network operator in the United Kingdom, with 32 million customers as of June 2023. The company was formed as Everything Everywhere in 2010 as a joint venture between Deutsche Telekom and France Telecom (now Orange S.A.). In 2012 it was rebranded to EE concurrently while launching the UK's first 4G mobile network.

Vodafone was originally part of Racal Electronics. The company was formed in 1985 and is headquartered in Newbury, Berkshire. The company owns and operates networks in 21 countries, with partner networks in 48 further countries.

Largest terrestrial mobile phone network operators

Company Country Subscriptions (in millions)
China Mobile China 974
Bharti Airtel India 496
Jio India 436
China Telecom China 390
China Unicom China 320
America Movil Mexico 307
MTN Group South Africa 289
Telefonica Spain 277
Vodafone United Kingdom 274
Orange France 241

Older Technology


iPod is a line of portable media players. The first version was released in 2001 and the product line was discontinued in 2022. Sales of iPods peaked in 2008. Apple sold an estimated 450 million iPod products

iPod product lines –

iPod (classic) – the original full-sized iPod line, marketed from 2001 to 2014, and retroactively named "classic" in 2007

iPod mini – a smaller version, marketed from 2004 to 2005

iPod nano – an even smaller version, marketed from 2005 to 2017

iPod shuffle – a series of tiny screen-less versions, marketed from 2005 to 2017

iPod touch – a series of iOS-based versions, marketed from 2007 to 2022

Compact disc

The compact disc was co-produced by Philips and Sony and released in 1982. By 2007, 200 billion CDs had been sold worldwide.

Standard CDs have a diameter of 120 mm (4.7 in) and are designed to hold up to 74 minutes of uncompressed stereo digital audio or about 650 MB of data.

CD formats –

CD-ROM – Read-only memory

CD-R – Recordable. Can be written once and read arbitrarily many times.

CD-RW – Rewritable. Can be written, read, erased, and re-written

The standard plastic case used by most manufacturers is known as a jewel case.


The DVD (Digital Video Disc or Digital Versatile Disc) is an optical disc. It was invented in Japan and released in 1996.

A standard DVD can store up to 4.7 GB of data.

Blank recordable DVD discs (DVD-R and DVD+R) can be recorded once using a DVD recorder and then function as a DVD-ROM. Rewritable DVDs (DVD-RW, DVD+RW, and DVD-RAM) can be recorded and erased many times.

Since 2008, DVD sales have declined more than 86%, due to a rise in customers buying on-demand and digital copies of films and the launch of streaming services.

The high-definition optical disc format war was between the Blu-ray Disc and Toshiba HD DVD optical disc standards for storing high-definition video and audio; it took place between 2006 and 2008 and was won by Blu-ray Disc.

Blu-ray Disc refers to the blue laser used to read the disc, which allows information to be stored at a greater density than is possible with the longer-wavelength red laser used for DVDs.

A standard Blu-ray Disc can store up to 25 GB of data. High-definition (HD) video may be stored on Blu-ray Discs with up to 1920 × 1080 pixel resolution.

Video recorder

The videocassette recorder, VCR, or video recorder, records analog audio and analog video from broadcast television or other source on a removable, magnetic tape videocassette.

Ampex introduced the Quadruplex videotape professional broadcast standard format with its Ampex VRX-1000 in 1956. It became the world's first commercially successful videotape recorder

In 1959 Toshiba announced a new method of recording known as helical scan, first implemented in reel-to-reel videotape recorders (VTRs).

The Telcan, produced by the UK Nottingham Electronic Valve Company in 1963, was the first home video recorder.

The Sony model CV-2000, first marketed in 1965, was their first VTR intended for home use.

In the 1970s, JVC’s VHS (Video Home System) won the ‘Videotape format war’ against Sony’s Betamax and Philip’s V2000. While Betamax was believed to be the superior format in the minds of the public and press (due to excellent marketing by Sony), consumers wanted an affordable VCR (which often cost hundreds of dollars less than a Betamax player).

DVD rentals in the United States first exceeded those of VHS in 2003.

The last VHS recorders were manufactured in 2016.

Cassette tape

The cassette tape was invented by Lou Ottens at Philips in 1963. Compact Cassettes come in two forms, either containing content as a prerecorded cassette (Musicassette), or as a fully recordable "blank" cassette.

Tape length usually is measured in minutes of total playing time. The most popular varieties of blank tape were C60 (30 minutes per side), C90 (45 minutes per side) and C120 (60 minutes per side).

Sales of CDs overtook those of prerecorded cassettes in the early 1990s. Sales of pre-recorded music cassettes in the US dropped from 442 million in 1990 to 274,000 by 2007.

Cassette tapes have seen a modest resurgence, and in the UK, sales of cassette tapes in 2021 reached its highest number since 2003.

Personal stereo

A personal stereo is also known as a personal cassette player.

The Sony Walkman was released in 1979. It became a popular and widely imitated consumer item in the 1980s. 220 million cassette-type Walkman were sold by the end of production in 2010.

Portable CD player

Discman was Sony's brand name for portable CD players. The first Discman, the D-50/D-5, was launched in 1984, two years after mass production of CDs began. The brand name was later changed to CD Walkman. Production ceased in 2008.



Vacuum tubes (thermionic valves) were the first active electronic components which controlled current flow by influencing the flow of individual electrons.

The simplest vacuum tube, the diode, was invented in 1904 by John Ambrose Fleming. Electrons can flow in only one direction through the device – from the cathode to the anode.

The triode, which consists of three electrodes inside an evacuated glass envelope: a heated filament or cathode, a grid, and a plate (anode), was the first practical electronic amplifier. Invented in 1906 by Lee De Forest.

William Shockley of Bell Labs invented the first transistor in 1947.

The MOSFET (metal-oxide-semiconductor field-effect transistor) was invented at Bell Labs in 1959. The MOSFET was the first truly compact transistor that could be miniaturised and mass-produced for a wide range of uses.

Jack Kilby and Robert Noyce created the first integrated circuit in 1958.

Very large-scale integration (VLSI) is the process of creating an integrated circuit (IC) by combining millions or billions of MOS transistors onto a single chip. VLSI began in the late 1970s.

Electronic components

Circuit Symbols for A-level-OCR-Physics A.png

Components can be classified as active or passive. Active components can control the flow of current, amplify power, and require an external source of energy. Passive components cannot control the current, have no power gain, and do not need an external source of energy.

Active components

Transistor – a semiconductor device used to amplify and switch electronic signals. The two types of transistors are the bipolar junction transistor (BJT) and the field-effect transistor (FET).

Thyristor – a four-layered semiconductor rectifier in which the flow of current between two electrodes is triggered by a signal at a third electrode.

Diode – a vacuum tube that allows current to flow in one direction only.

Light-emitting diode (LED) – a semiconductor diode that converts applied voltage to light.

Photodiode – a semiconductor capable of converting light into either current or voltage.

Triode – an electronic amplifying vacuum tube.

Passive components

Resistor – an electronic component that restricts the flow of current in an electrical or electronic circuit.

Rheostat – a variable resistor that controls the flow of electric current by changing the resistance.

Potentiometer – a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.

Thermistor – an electrical resistor whose resistance is greatly reduced by heating.

Memristor – an electrical component that limits or regulates the flow of electrical current in a circuit and remembers the amount of charge that has previously flowed through it.

Capacitor – formerly known as a condenser, is a device that stores electrical energy in an electric field by accumulating electric charges on two closely spaced surfaces that are insulated from each other.

Inductor – an electrical component that stores energy in a magnetic field when electric current flows through it.

A flip-flop or latch is a circuit that has two stable states and can be used to store state information.


A semiconductor is a substance such as silicon or germanium whose electrical conductivity is intermediate between that of a conductor and an insulator. Its resistivity falls as its temperature rises

In semiconductor production, doping is the process of intentionally introducing impurities into an extremely pure (also referred to as intrinsic) semiconductor to change its electrical properties. The impurities are dependent upon the type of semiconductor. Lightly and moderately doped semiconductors are referred to as extrinsic. A semiconductor doped to such high levels that it acts more like a conductor than a semiconductor is referred to as degenerate.

n-type semiconductor – a semiconductor in which electrical conduction is due chiefly to the movement of electrons.

p-type semiconductor – a semiconductor in which electrical conduction is due chiefly to the movement of positive holes.

Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuits. Electronic circuits are gradually created on a wafer, typically made of pure single-crystal semiconducting material. Silicon is almost always used.

Integrated Circuits

An integrated circuit (chip, or microchip) is a set of electronic circuits on one small plate (‘chip’) of semiconductor material, normally silicon. Large numbers of miniaturized transistors and other electronic components are integrated together on the chip.

Generations of integrated circuits

Name Year Transistor count Number of logic gates
Small-scale integration (SSI) 1964 1 to 10 1 to 12
Medium-scale integration (MSI) 1968 10 to 500 13 to 99
Large-scale integration (LSI) 1971 500 to 20,000 100 to 9,999
Very large-scale integration (VLSI) 1980 20,000 to 1,000,000 10,000 to 99,999

VLSI was made practical by technological advancements in semiconductor device fabrication.

Ultra large-scale integration (ULSI) was proposed for chips of more than 1 million transistors.

Moore’s Law states that “the number of transistors that can be placed inexpensively on an integrated circuit doubles approximately every two years”. The law is named after Intel co-founder Gordon E. Moore, who described the trend in his 1965.

An application-specific integrated circuit (ASIC) is an integrated circuit chip customized for a particular use, rather than intended for general-purpose use.

A gate array is an approach to the design and manufacture ASICs using a prefabricated chip with components that are later interconnected into logic devices.


Foxconn, based in Taiwan, is the world's largest maker of electronic components. Up to the iPhone 4, all iPhones and other Apple devices, such as iPod Touch models and iPads, were manufactured by Foxconn.

Taiwan Semiconductor Manufacturing Company (TSMC) is the world's most valuable semiconductor company. The company was founded in Taiwan in 1987 by Morris Chang. In 1997 it became the first Taiwanese company to be listed on the New York Stock Exchange.

Logic Gates

A logic gate is a device implementing a Boolean function; that is, it performs a logical operation on one or more logical inputs, and produces a single logical output. The primary way of building logic gates uses diodes or transistors acting as electronic switches. Today, most logic gates are made from MOSFETs.


The NOT gate is more commonly called an inverter. The circle on the symbol is called a bubble and is used in logic diagrams to indicate a logic negation.

The output of the exclusive-OR (XOR) gate is true only when the two input values are different.

The XNOR is the logical complement of the XOR gate.

All Boolean logic gates can be created from a suitable network of NAND gates or NOR gates.

Microprocessors may contain more than 100 million logic gates.

Big Tech

Big Tech, also known as the Tech Giants, refers to the most dominant companies in the information technology industry. The term when referring to American technology companies notably the five largest from the United States: Alphabet (Google), Amazon, Apple, Meta (Facebook), and Microsoft.

Alphabet (Google)

Google was founded in 1998 by Larry Page and Sergey Brin while they were Ph.D. students at Stanford University.

The Google HQ in Mountain View, California, is known as the Googleplex.

Eric Schmidt served as the CEO of Google from 2001 to 2011 and the company's executive chairman from 2011 to 2015.

Sundar Pichai is the CEO of Alphabet and Google.

In 2006, Google acquired YouTube for $1.65 billion in Google stock.

Waze provides satellite navigation software on smartphones and other computers that support the Global Positioning System (GPS). The company was acquired by Google in 2013.

In 2015, Google announced plans to reorganize its various interests as a conglomerate named Alphabet Inc. Google became Alphabet's largest subsidiary and the umbrella company for Alphabet's Internet interests.

Google Ads (previously known as Google AdWords) is an online advertising platform developed by Google, where advertisers bid to display brief advertisements, service offerings, product listings, and videos to web users. Google Ads is the main source of revenue for Alphabet.

Google Drive is a file storage and synchronization service created by Google. It allows users to store files in the cloud, share files, and edit documents, spreadsheets, and presentations with collaborators.

Google Cloud Platform is a suite of cloud computing services.

Google Earth is a virtual globe program that was originally called Earth Viewer and was created by Keyhole, Inc. It maps the earth by the superimposition of images obtained from satellite imagery, aerial photography and GIS over a 3D globe.

Google Maps is a web mapping platform and consumer application. It offers satellite imagery, aerial photography, street maps, 360° interactive panoramic views of streets (Street View), real-time traffic conditions, and route planning for traveling by foot, car, bike, and public transportation. As of 2020, Google Maps was being used by over one billion people every month around the world.

Waymo is Google’s self-driving car project. The company was founded in 2009.

Google Glass was a brand of smart glasses. Google started selling a prototype of Google Glass in 2013, before it became available to the public in 2014.The headset received a great deal of criticism amid concerns that its use could violate existing privacy laws, and in 2015 Google announced that it would stop producing the Google Glass prototype.

Google TV was a smart TV operating system from Google co-developed by Intel, Sony and Logitech. It launched in 2010 and was succeeded in 2014 by Android TV.

Daydream is a discontinued virtual reality (VR) platform which was developed by Google, primarily for use with a headset into which a smartphone is inserted. Google is discontinued Daydream in 2019, due to a lack of interest from both consumers and developers.

Ruth Kedar designed the Google logo.


Amazon was founded by Jeff Bezos from his garage in Bellevue, Washington, in 1994.

The first book sold on was Douglas Hofstadter’s Fluid Concepts and Creative Analogies: Computer Models of the Fundamental Mechanisms of Thought

Amazon went public in 1997. It began selling music and videos in 1998.

Amazon opened a physical Amazon Books store in University Village in Seattle in 2015.

Amazon Web Services (AWS) was launched in 2002.

Andy Jassy replaced Jeff Bezos as CEO in 2021.

IMDB was purchased by Amazon in 1998.

Audible is an American online audiobook and podcast service that allows users to purchase and stream audiobooks and other forms of spoken word content. It was purchased by Amazon in 2008.

Goodreads was purchased by Amazon in 2013.

Twitch was purchased by Amazon in 2014.

Amazon Prime is a paid subscription service that gives users access to additional services otherwise unavailable or available at a premium to other Amazon customers. Services include same, one- or two-day delivery of goods, and streaming music and video

Amazon Music is a music streaming platform and online music store.

Amazon Kindle is a series of e-readers designed and marketed by Amazon. Launched in 2007.

Amazon Alexa is a virtual assistant, first used in the Amazon Echo smart speaker and the Echo Dot.

Amazon Fresh is a grocery retailer with physical stores and delivery services in most major U.S. cities.


Apple was founded by Steve Jobs, Steve Wozniak, and Ronald Wayne in 1976, to develop and sell personal computers. It was incorporated as Apple Computer, Inc. in 1977, and was renamed as Apple Inc. in 2007, to reflect its shifted focus towards consumer electronics.

Ronald Wayne left after 12 days and relinquished his (10%) share of the partnership back to Jobs and Wozniak for $800.

John Sculley was CEO of Apple from 1983 to 1993.

Tim Cook has been CEO of Apple since 2011.

Apple Park is the corporate headquarters of Apple, located in Cupertino, California. The main building's scale and circular design, by Norman Foster, have earned the structure the media nickname "the spaceship". Opened in 2017.

Jony Ive was the chief design officer of Apple from 1997 until 2019. He played a vital role in the designs of the iMac, iPod, iPhone, iPad, and MacBook.

The Apple I went on sale in July 1976 and was market-priced at $666.66

Apple Lisa was released in 1983. It is one of the first personal computers to present a graphical user interface (GUI) in a machine aimed at individual business users. Only 10,000 were sold in two years and it was considered a commercial failure.

Apple Mac was introduced by Steve Jobs in 1984. Its debut was signified by “1984”, a $1.5 million television commercial modeled after the George Orwell novel and directed by Ridley Scott, that aired during the 1984 Super Bowl.

NeXT was founded in 1985 by Steve Jobs after he was fired from Apple the same year. NeXT introduced the first NeXT Computer in 1988. Apple purchased NeXT in 1996.

iMac was a range of all-in-one Macintosh desktop computers built by Apple. It was sold from 1998 to 2003. iMac was the first PC sold without a floppy drive.

Newton platform was an early personal digital assistant and the first tablet platform developed by Apple, the second platform being iOS, used in the iPhone, iPod Touch and iPad. Development of the Newton platform started in 1987 and ended in 1998.

Apple introduced the iBook, a laptop aimed at the consumer and education markets, in 1999. Apple replaced the iBook line with the MacBook in 2006 during the Mac transition to Intel processors.

The first Apple Store retail locations were opened in the US in 2001.

iTunes Store was introduced in 2003. The service offered music downloads for 99 cents a song and integration with the iPod. The iTunes Store quickly became the market leader in online music services, and by 2010 was the world's largest music retailer.

In 2008, Apple launched the App Store to sell third-party applications for the iPhone and iPod Touch.

Beats Music was acquired by Apple as part of its purchase of Beats Electronics in May 2014. Beats Music stopped accepting new subscriptions when Apple Music launched in June 2015.

Apple bought Shazam in 2018.

FaceTime works by using an Apple device’s mobile data or Wi-Fi connection to make voice and/or video calls to other Apple device users.

Retina Display is a brand name used by Apple for liquid crystal displays which they claim have a high enough pixel density that the human eye is unable to notice pixelation at a typical viewing distance.

Apple Watch is a line of smartwatches that incorporates fitness tracking, health-oriented capabilities, and wireless telecommunication, and integrates with iOS and other Apple products and services. An estimated 100 million units had been sold by 2020

AirPods are wireless Bluetooth earbuds first announced in 2016.

The Apple logo was created by Rob Janoff.

"There's an app for that" which was first used in a commercial for the iPhone, is a slogan that has been officially trademarked by Apple.

Meta (Facebook)

Facebook was founded in 2004 by Mark Zuckerberg and some fellow Harvard College students. Its predecessor was a website called Facemash, and it was originally known as Thefacebook. Initially this was only opened to people with a Harvard email address.

Zuckerberg had previously worked on a similar project with fellow students Cameron Winklevoss, Tyler Winklevoss, and Divya Narendra. He eventually quit to do Thefacebook, but his ex-collaborators say he stole their concept and ideas and they wanted recompense. They eventually came to a settlement in 2008, with each of the trio receiving 1.2m shares in Facebook.

The company announced 500 million users in July 2010.

Facebook acquired Instagram in 2012 for approximately US$1 billion in cash and stock.

Facebook's initial public offering came in 2012, at a share price of $38. The company was valued at $104 billion.

Facebook acquired Oculus, a VR headset startup, in 2014. The Oculus Rift was the first virtual reality headset to provide a realistic experience at an accessible price.

WhatsApp was acquired by Facebook in 2014 for approximately US$19.3 billion

Sheryl Sandberg was chief operating officer of Facebook from 2008 to 2022.

In October 2021, Facebook rebranded itself as Meta Platforms, Inc., or simply "Meta" in an attempt to own the Metaverse, a concept for a 3D version of the internet. This change does not affect the name of the Facebook social networking service itself, instead being like the creation of Alphabet as Google's parent company in 2015.

For information on the Facebook website see Lifestyle/Social Media and the Internet


Microsoft was founded in 1975 in Albuquerque by Bill Gates and Paul Allen. Microsoft is a portmanteau of “microcomputer software”. The company headquarters are in Redmond, Washington.

Steve Ballmer replaced Bill Gates as CEO in 2000, and in 2014 Satya Nadella took over as CEO.

In April 2019, Microsoft became the third US public company to be valued at over $1 trillion after Apple and Amazon.

Microsoft was the world's largest software maker by revenue as of 2022.

Microsoft bought Skype Technologies for $8.5 billion in 2011.

Microsoft bought LinkedIn for $26 billion in 2016.

GitHub is a platform and cloud-based service for software development and version control using Git. It has been a subsidiary of Microsoft since 2018.

Microsoft HoloLens is an augmented reality (AR)/mixed reality (MR) headset developed and manufactured by Microsoft.

Microsoft Azure is a suite of cloud computing services.

Visual Studio is an integrated development environment (IDE) from Microsoft. It is used to develop computer programs including websites, web apps, web services and mobile apps.

Microsoft Store is a digital platform for the purchase and download of apps, games, and software from Microsoft and its partners.

Encarta is a discontinued digital multimedia encyclopaedia published by Microsoft from 1993 to 2009.

Microsoft Mobile was a subsidiary of Microsoft involved in the development and manufacturing of mobile phones. It was established in 2014 following the acquisition of Nokia's Devices and Services division by Microsoft. The company sold the Lumia range of phones, but in 2016 Microsoft abandoned its mobile business.