Before transistors, which regulate the flow of electricity, vacuum tubes—glass tubes containing no gas that resemble light bulbs—served as the electronic switches in computers.

Before the invention of transistors, vacuum tubes made radio possible

Discovered by Thomas Edison, vacuum tubes allow electrical currents to travel through empty space. Later modified into a diode—keeping current flowing in only one direction—vacuum tubes allowed electronics to turn alternating current into direct current.

Transistors in traditional computers are physically limited to atomic scales

As computer parts shrink, transistors—tiny switches that control the path of electrical signals—become obsolete because electrons can quantum tunnel through switch barriers. This makes quantum computers, which take advantage of quantum effects, an enticing alternative.

Transistors are the foundational components of integrated circuits and microchips and manage the processing of electronic signals by controlling the flow of electricity.

Logic gates—digital versions of conditional statements, such as 'if 0 and 1, then 1'—are specialized circuits that combine multiple digital signals, like the binary code representing numbers, into a single output, thereby allowing machines to perform math.

Watch a timeline of the history of electricity, from observations of static electricity in antiquity to the War of the Currents—a rivalry to establish the ideal system for electric grids.

An explanation of Turing machines—the foundations of digital algorithms and computers

The device reads data, overwrites or ignores it, and then moves on to the next piece of data based on a set of programmed rules. By imagining this data as zeros and ones—binary that makes up computer code—Turing machines became the theoretical models for how any algorithm could be run on a computer if the procedure could be coded into a set of digital rules.

FLOW-MATIC was the first programming language resembling the English language

As part of the team working on UNIVAC—the first commercially produced electronic digital computer in the US—Grace Hopper helped develop the system that enabled nonprogrammers and businesspeople without a strong mathematics background to use the machine effectively, thereby enhancing the computer's commercial viability.

Semiconductor chips are electronic devices that store and process information

They can contain billions of microscopic switches on a chip smaller than a fingernail. An article provides a quick overview of how the devices work and how they’ve provided the backbone of the computer age.

CES debuted in 1967 amid a wave of miniaturization in at-home electronics

The rapid development of integrated circuits—the basis of computing power—in the 1960s catalyzed an industrial shift toward miniature devices, including pocket transistor radios, smaller TVs, and more. This first consumer electronics trade show (with a slate of 117 exhibitors and 17,000 attendees) sought to make everyday electronics accessible and portable. See a timeline of early consumer tech with photos.

The Model K—named for its construction on a kitchen table—was the first electromechanical digital binary adder, which used an electric circuit to provide the sum of a pair of zeroes and ones in binary.

All computers are defined by their ability to input, store, process, and output data

From wooden machines to wearable tech, computers have changed a lot in appearance, but they all still perform the same essential tasks. Early computers were made of wood and metal—some were so big that they filled entire rooms just to solve simple math problems.

A simple explanation of semiconductors

Semiconductor chips are electronic devices that store and process information. Today they can contain billions of microscopic switches on a chip smaller than a fingernail. The article provides a quick overview of how the devices work and how they've provided the backbone of the computer age.

A timeline of computer history

The earliest computers bear little resemblance to the computing devices that most people rely on today. This timeline graphic from the Computer History Museum tracks their evolution, from the early days of bulky mainframes that only experts generally used through to the personal computing revolution and on to the modern mobile era. Readers will learn important context ahead of the next major computing platform shift.

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

There is a limit to how small transistors can become because they rely on being able to allow or block the flow of electrons, but quantum effects allow electrons to leak through these barriers, generating heat, current loss, and potential data errors.

Cathode-ray tube televisions are examples of electron accelerators

CRT TVs work by converting electricity into heat, which causes electrons to be emitted from the rear of the device in three beams responsible for the colors red, green, and blue. Electromagnets direct electrons to phosphor molecules on the screen, which emit light and illuminate the pixels.

More than 2,000 years ago, a hand-powered model of the solar system called the Antikythera mechanism—the oldest example of an analog computer—could predict solar eclipses.

The first compiler to facilitate communication with computers was developed by Grace Hopper

The A-0 program linker automatically translated mathematical symbols into machine-readable binary code. Although it took two years for computer executives to get on board with the idea, the technology was foundational to future programming languages that allowed computers to understand commands written in word-based languages.

Cathode rays are beams of electrons that emit light when hitting a fluorescent screen

When these beams are emitted into an evacuated tube containing charged plates or a nearby magnet, deflections are observed due to the electron charge. In 1897, J.J. Thomson's calculations of this deflection led to his discovery of the subatomic particle.

Lasers, semiconductors, medical imaging, and atomic clocks rely on quantum mechanics

Semiconductors, crucial in electronics, operate based on quantum superposition. Lasers use stimulated emission, a quantum process, and MRI machines leverage the quantum spin of hydrogen atoms for imaging. Atomic clocks measure time with unprecedented precision using quantum transitions.

Since computers rely on the distribution of electrons in microchips to represent binary code, cosmic rays and ionizing radiation from radioactive elements can introduce software errors by detaching electrons from atoms.

Superconducting qubits have become foundational to today’s quantum computing efforts

Relying on electrons experiencing no friction across metal, these qubits require extremely low temperatures and behave like artificial atoms. The first superconducting qubit, invented in 1999, was large enough to be seen with the naked eye.

The first computer virus was created by a USC doctoral candidate in 1983

A year after creating malware in a controlled experiment that multiplied until it took over all of a computer's memory, Fred Cohen went public with his research and its risks. He called the self-replicating software a "computer virus," a term Cohen's advisor, Leonard Adleman, coined to describe its infectious behavior. (Some readers may experience a paywall.)

The terms 'bug' and 'debugging' were popularized by Grace Hopper's team

Engineers working on the Mark II computer at Harvard University identified a moth in one of its components in 1947, which caused it to malfunction. Describing the incident as the "first actual case of bug being found," the term first used by Thomas Edison in 1878 to describe faults in an apparatus caught on.

Logic bomb viruses can awaken from a dormant phase without human input

Theoretically, computer viruses can remain idle indefinitely while awaiting specific user actions, as instructed by their code. However, logic bombs—embedded code that triggers when specific conditions are met—can automatically execute viruses, such as when a certain date or time is reached.

Turing machines consist of an infinite tape, a read-write mechanism and instructions

Based on the information the mechanism reads on the tape, the machine follows the applicable instruction (e.g., if you read a 1, write a 0) and may proceed to the next cell of data. Given enough time and memory, Alan Turing proposed such a machine could perform any computation.

A collective effort from multiple scientists and inventors led to the light bulb

While Thomas Edison's thin carbon filament design made light bulbs commercially viable, prior contributions, such as Joseph Swan's development of the first successful incandescent filament electric lamp, made its eventual invention possible.

Named after Nikola Tesla, who pioneered alternating current power systems, the Tesla coil was the first device to wirelessly transmit electricity.

NASA purchased about 60% of all integrated circuits from 1961 to 1965

The US government adopted the new technology to support the development of the Apollo Guidance Computer, which would help astronauts fly to the moon. This drove manufacturing up and costs down, setting the stage for the modern computing era.

The process of electronic funds transfer was approved in the US in 1978

An electronic funds transfer is the transfering of money from one bank account to another via computer-based systems. When it was first introduced, it was revolutionary. A video from 1980 aimed to explain the value of electronic funds transfer to consumers at the time.

Alternating current was used to commit the first execution by electric chair

Dubbed the "executioner's current," the device was designed in Thomas Edison's lab by Harold Brown—an opponent of George Westinghouse and Nikola Tesla. The effort aimed at discrediting AC technology and gain favor for Thomas Edison's direct current as part of "The Current War."

See how computer memory really works—from binary bits to modern RAM

The video explains how computers store information as 1s and 0s, how RAM functions as fast working memory, and why systems utilize different types of storage. The video demonstrates how this process enables computers to operate.

Before 1932, when particle accelerators were first used for nuclear research, scientists relied on naturally radioactive substances to advance their understanding of the atomic nucleus.

The foundation for computer viruses was published after its creator's death

In the late 1940s, Hungarian American mathematician, scientist, and engineer John von Neumann gave a series of lectures where he explained the theoretical framework for a computer program that could replicate itself—the von Neumann Universal Constructor. His lectures were later compiled and published in 1966, nine years after his death from cancer.

Tesla's alternating current power's most of the world's electric grids

In 1879, Thomas Edison’s light bulb relied on direct current, but such currents can't efficiently transmit power over long distances. Nikola Tesla introduced alternating current, which feature far fewer energy loses. Despite Edison’s attempts to discredit AC, Tesla proved its efficiency by lighting the 1893 Chicago World’s Fair.

The history and operation of SIGABA, the US counterpart of the Nazi Enigma machine

Developed by the US Army and US Navy, over 10,000 of these machines were deployed by the end of World War II to encrypt messages for the armed forces using three series of rotors. The device would continue to be used until the 1950s, while personal computers were shown to possess enough computing power to crack it by 2021.

Today's massive data centers evolved from single-room mainframes

Punch card computers from the late 1940s were used to store and process a company's data locally before the advent of desktop computers. As the amount of data and company sizes increased alongside the miniaturization of technology, mainframes were replaced by local server rooms and external facilities with interconnected servers running cloud-based and AI software.

Integrated circuits come in digital, analog, or mixed types

Each type can be further divided based on application, technology, and integration level. Digital ICs are used in computer memories and microprocessors, while analog ICs process continuous signals within sensors, including temperature, light, and sound.

The history of Vannevar Bush, who influenced the creation of hyperlinks and the NSF

As director of the Office of Scientific Research and Development, Bush submitted a report outlining how to support basic research at American colleges and universities by establishing an independent funding agency, which laid the groundwork for the National Science Foundation. His idea for a Memex machine that connected microfilm content in "associative trails" of links would influence Douglas Engelbart's development of hypertext.

Quantum computers harness weird physics to explore unsolvable problems

Classical computers manipulate bits as either 0 or 1, but quantum computers use qubits to hold combinations of both, enabling new algorithms. This new approach could one day help with breakthroughs in medicine, chemistry, and AI.

An integrated circuit combines major circuit components onto a single device

Before 1958, these components were fabricated separately before manual assembly, introducing human error, delays, and higher costs. The invention of the IC laid the foundation for automated manufacturing, miniaturization, and improvements to speed and energy efficiency.

A dispute about the origin of twitching frog legs led to the invention of the first battery

Experiments by Luigi Galvani on exposed frog leg nerves showed activity when they were hung from iron railings and brass hooks, suggesting the existence of "animal electricity" that discharged when connected to metals. Alessandro Volta's voltaic pile, which stacked metals with an inorganic electrolyte, showed that electricity originates from chemical reactions.

Niagara Falls helped decide the battle between AC and DC power

In the 1890s, Niagara Falls became the proving ground for alternating current (AC) when Tesla and Westinghouse built the first large-scale AC hydroelectric plant—defeating Edison’s push for direct current (DC) in the US electrical system.

Grace Hopper was inspired to join the armed forces after the attack on Pearl Harbor

Despite being too old to enlist and weighing below the required minimum to serve, Hopper was granted an exemption and assigned to work on the first electromechanical computer produced in the US. She and her team spent three months using the device to solve equations needed to design the implosion mechanism for the atomic bomb.

The first algorithmic random number generator was developed in 1946

Although previous methods of randomness involved physical tools with limited outcomes, such as dice, or relied on chaotic variables for number generation, such as electronic noise, John Von Neumann's middle-square method turned the problem into a mathematical computation. It has since been replaced by methods that generate numbers from unique initial values, such as the time on a clock.

At the age of seven, Grace Hopper dismantled alarm clocks

Foreshadowing a career in computers, Hopper exhibited a curiosity for gadgets at a young age and took apart seven clocks, determined to understand how they worked. Despite having a dollhouse, Hopper built an elevator for it and showed a greater interest in building toy furniture than playing with dolls.

Computational and biological systems share fundamental principles, like randomness

Proposed by Alan Turing and John von Neumann, the concept originates from how DNA and computers run by executing encoded instructions in parallel. The advent of AI and the temperature parameter has seen neural networks mimic the randomness of protein encoding.

Your iPhone started with a Cold War secret

Silicon Valley wasn't supposed to happen. A stretch of California orchard land somehow became the place that built the modern world: chips, PCs, the internet, the smartphone, and now AI. But the real story isn't the garage myth. It's a series of contradictions hiding in plain sight.

Solid neon mirrors help trap single electrons to create stable quantum bits

Researchers created this new unit of information for a quantum computer by trapping a single electron near the surface of solid neon. The electron was held in its quantum state by attraction to its mirror image.

Quantum computers use qubits to solve problems much faster than classical machines

Unlike regular computers, where each bit is either 0 or 1, quantum computers use qubits, which can simultaneously be both—allowing for massive parallel processing power. Google’s quantum processor once solved a problem in seconds that would have taken a supercomputer 47 years.