Milestones: the ground the industry stands on

1800 · Alessandro Volta

The voltaic pile

A stack of alternating zinc and copper discs separated by brine-soaked cloth, producing a steady electric current rather than the momentary discharge of a static machine.

Everything downstream needs current that keeps flowing. Static electricity had been known for centuries and was useless for it. This is the first thing on the list because without a continuous source there is nothing to modulate, switch or send.

Volta's 1800 letter to the Royal Society describing the pile

1820 · Hans Christian Ørsted

A current deflects a compass needle

A wire carrying current was observed to move a nearby compass needle, showing that electricity and magnetism are aspects of one phenomenon rather than two curiosities.

Every motor, every transformer, every read head over a disk platter and every signal induced onto the wrong pair in a cable bundle is this observation, applied. Crosstalk is Ørsted's experiment happening when you did not ask for it.

Ørsted's 1820 report on the effect of a current on a magnetic needle

1831 · Michael Faraday

Electromagnetic induction

A changing magnetic field induces a current in a nearby conductor. The reciprocal of Ørsted: not only does current make magnetism, changing magnetism makes current.

This is generation, transformation and every inductive coupling problem in one law. It is also why twisted pair works: twist the conductors and the interference induced into each is roughly equal, so the difference between them - the thing the receiver actually reads - is largely clean.

Faraday's Experimental Researches in Electricity, first series, 1831

1865 · James Clerk Maxwell

A dynamical theory of the electromagnetic field

A set of equations describing electricity, magnetism and light as one field phenomenon, predicting that electromagnetic waves propagate at the speed of light.

The prediction came before the demonstration, which is worth noticing: radio existed on paper for two decades before anyone made it. Every wireless standard is an engineering treatment of this result, and propagation, attenuation and antenna design are all applied Maxwell.

Maxwell, A Dynamical Theory of the Electromagnetic Field, Philosophical Transactions, 1865

1882 · Thomas Edison's Pearl Street Station, New York

Commercial electricity distribution

A central generating station selling electricity to paying customers over a distribution network, rather than each building generating its own.

**The first utility, and therefore the first argument about centralised versus local provision** - the same argument that later produced timesharing, then the data centre, then cloud. The economics that favour a shared plant over a private one have not changed since 1882; only the plant has.

Pearl Street Station, in service September 1882

1887 · Heinrich Hertz

Electromagnetic waves demonstrated

A spark-gap transmitter and a loop receiver, showing that the waves Maxwell had predicted existed, could be reflected and refracted, and travelled at the predicted speed.

The moment radio became an engineering problem rather than a mathematical one. Hertz reportedly saw no use for it, which is a useful reminder about the distance between a demonstration and an application.

Hertz's 1887-88 experiments on electromagnetic waves

1897 · J. J. Thomson

The electron

Cathode rays shown to consist of particles far lighter than any atom, carrying negative charge.

Everything before this treated electricity as a fluid or a field without knowing what was actually moving. Knowing the carrier is what makes the valve, the transistor and semiconductor physics possible - you cannot deliberately control something you have not identified.

Thomson's 1897 cathode ray experiments at the Cavendish Laboratory

1904 · John Ambrose Fleming

The thermionic valve

A heated filament in an evacuated tube, allowing current in one direction only - the first electronic diode.

Rectification is the first thing you can do to a signal that is not simply carrying it. Detection of radio signals starts here, and so does the idea that a device can act on a signal rather than merely conduct it.

Fleming's 1904 patent for the oscillation valve

1906 · Lee de Forest

The triode, and amplification

A third electrode added to the valve, letting a small voltage control a much larger current.

**Amplification is the property that makes long-distance anything possible.** A signal that weakens with distance can now be rebuilt. Every repeater, every line amplifier and eventually every logic gate is a descendant of controlling a large current with a small one.

de Forest's audion patents, 1906-1908

1947 · John Bardeen, Walter Brattain and William Shockley, Bell Labs

The transistor

A solid-state device doing the valve's job - amplifying and switching - without a vacuum, a heater or the fragility of glass.

The valve worked but could not scale: it was large, hot, power-hungry and it failed. Everything about modern computing follows from being able to make this device small, cheap and reliable, and then to make a great many of them at once.

Bell Labs, December 1947 demonstration of the point-contact transistor

1958 · Jack Kilby at Texas Instruments, and Robert Noyce at Fairchild

The integrated circuit

Multiple components fabricated on a single piece of semiconductor rather than wired together as discrete parts.

The step from 'we can make a transistor' to 'we can make a million of them and they are all connected correctly'. Wiring components by hand has a hard ceiling; photolithography does not have one in the same way, which is the whole of the last sixty years.

Two independent inventions, months apart, with different approaches: Kilby's demonstration was in 1958, Noyce's planar process work in 1959. The planar approach is the one that scaled. Both are credited.

Kilby's 1958 demonstration at Texas Instruments; Noyce's 1959 planar integrated circuit at Fairchild

1965 · Gordon Moore

Moore's law

An observation, in a trade magazine article, that the number of components on an integrated circuit had been doubling roughly annually and would likely continue.

**It is an observation that became a plan.** The industry organised its roadmaps around it, which made it partly self-fulfilling for half a century. Worth understanding as economics rather than physics: the doubling continued because enormous capital was deployed on the assumption that it would.

Moore, Cramming more components onto integrated circuits, Electronics, April 1965

1971 · Intel 4004, designed by Federico Faggin, Ted Hoff, Stanley Mazor and Masatoshi Shima

The microprocessor

A complete central processing unit on one chip, originally built for a calculator.

The point is not the chip but the change in who could build a computer. Once a processor is a component you buy rather than a system you design, computers stop being capital projects. **Everything on the company timeline after 1975 depends on this being true.**

Intel 4004, announced November 1971

1804 · Joseph Marie Jacquard

Punched cards control a machine

A loom whose woven pattern is determined by a chain of punched cards, each row of holes selecting which warp threads lift.

**The first separation of a program from the machine that runs it.** The loom does not know what it is weaving; the cards do. That distinction - hardware that is general, instructions that are specific - is the one every computer since has been built on, and it arrived a century and a half early in a textile mill.

Jacquard's loom, demonstrated from 1801 and widely adopted after 1804

1854 · George Boole

An investigation of the laws of thought

An algebra in which variables take only two values and logical reasoning becomes calculation.

Boole was doing philosophy, not engineering, and there were no electrical circuits to apply it to. Eighty-three years later Shannon noticed the correspondence between his algebra and switching circuits. **A result can sit unused for three generations and then turn out to be the foundation of an industry**, which is worth remembering about anything currently filed as impractical.

Boole, An Investigation of the Laws of Thought, 1854

1936 · Alan Turing

On computable numbers

A definition of what it means for something to be computable, by way of an abstract machine, together with a proof that some questions cannot be decided by any such machine.

It establishes both that a general-purpose computing machine is possible and that there are limits to what it can be asked. The second half matters more often than people expect: a great many practical problems in this field are unsolvable in general and are handled with heuristics that mostly work.

Turing, On Computable Numbers, Proceedings of the London Mathematical Society, 1936

1937 · Claude Shannon

Boolean algebra describes switching circuits

A master's thesis showing that relay and switching circuits can be analysed and designed using Boolean algebra.

This is the hinge between electrical engineering and logic. Before it, a switching circuit was something you built and tested; after it, it is something you can reason about symbolically and prove correct. Every piece of digital design rests on this equivalence.

Shannon, A Symbolic Analysis of Relay and Switching Circuits, MIT, 1937

1945 · John von Neumann, drawing on the EDVAC group's work

The stored-program computer

A draft report describing a machine that holds its instructions in the same memory as its data, so a program can be loaded, changed and even modified while running.

Before this, changing what a computer did meant rewiring it. Afterwards it meant loading different data. Every idea downstream - operating systems, compilers, malware, virtualisation - depends on instructions and data being the same kind of thing in the same place.

Circulated as the First Draft of a Report on the EDVAC under von Neumann's name alone, which has been contested ever since: the design work involved Eckert, Mauchly and others, and the sole attribution was a consequence of how the draft was distributed rather than a claim about who did what.

First Draft of a Report on the EDVAC, 1945

1948 · Claude Shannon

A mathematical theory of communication

Information given a precise measure in bits, and a proof that every channel has a capacity above which reliable communication is impossible and below which it is achievable however noisy the channel is.

**This is the most load-bearing single result on this page for anyone who works with networks.** It says a noisy link is not simply a worse link - it is a link with a number attached, and that number is not negotiable by engineering effort. Every modulation scheme, every error-correcting code and every argument about how much can be pushed down a given piece of copper is an attempt to approach a bound Shannon proved exists.

Shannon, A Mathematical Theory of Communication, Bell System Technical Journal, 1948

1963

ASCII

A standard assignment of numbers to characters, so that machines from different manufacturers could exchange text and agree on what it said.

**Agreement is the product, not the encoding.** Any consistent mapping would have worked; what mattered was that everyone used the same one. The same lesson is relearned constantly, and the cost of relearning it is visible in every mojibake bug and every system that still assumes one byte per character.

ASA X3.4-1963, the first ASCII standard

1991

Unicode

A single character set intended to cover every writing system, replacing the patchwork of incompatible national encodings.

ASCII solved agreement for one language and created a problem for everyone else. Unicode is the admission that text is harder than it looks: normalisation, collation, bidirectional text and the fact that a user-visible character is not a code point. **This site's own translation rules exist because of what is in this entry** - proper diacritics are cheap now and were not always.

The Unicode Standard, version 1.0, 1991

1928 · Fritz Pfleumer

Magnetic tape

Iron oxide bonded to a paper, later plastic, strip - a flexible medium that could be magnetised in a pattern and read back.

The first storage medium that was cheap per unit of capacity and physically compact. It is also the ancestor of a distinction that still governs backup design: tape is sequential, and sequential media are excellent at throughput and terrible at random access.

Pfleumer's 1928 patent for magnetic recording on paper tape

1928 · IBM

The 80-column punched card

A rectangular-hole card holding eighty characters, which became the dominant format for machine-readable data for the next four decades.

**Eighty columns is why terminals are eighty columns wide, and why so much software still assumes an eighty-character line.** A physical constraint from a cardboard rectangle propagated into screens, then into style guides, then into linters, long after the last card was punched. Formats outlive their reasons.

IBM's 80-column card, introduced 1928

1956 · IBM, RAMAC 305 with the 350 disk unit

The first hard disk drive

Fifty rotating 24-inch platters storing about five million characters, with a moving head that could reach any record without winding through everything before it.

**Random access is the point, not capacity.** A tape must be traversed; a disk can be addressed. Every database, filesystem and index assumes you can go straight to a location, and that assumption starts here. The capacity was trivial and the idea was not.

IBM 350 disk storage unit, shipped with the RAMAC 305, 1956

1971 · IBM

The floppy disk

A flexible magnetic disk in a protective sleeve, originally shipped to load microcode into mainframes, then adopted as removable storage.

It made data portable in a way tape never quite managed for ordinary use, and in doing so created the software industry's distribution model and its first serious piracy problem in the same object. **The save icon on software written this decade is still a picture of one.**

IBM's 8-inch flexible disk, 1971

1980 · IBM 3380

A gigabyte in one cabinet

The first disk product to reach a gigabyte of capacity, in a unit the size of a large refrigerator and priced accordingly.

Useful as a yardstick rather than a breakthrough. **A capacity that needed a refrigerator-sized cabinet and a six-figure price in 1980 now costs less than lunch and fits on a fingernail** - and every architectural assumption made when storage was scarce was made under the earlier conditions.

IBM 3380, announced 1980

1980 · Fujio Masuoka, Toshiba

Flash memory

Non-volatile solid-state memory that can be erased and rewritten in blocks, without moving parts.

It removes the last mechanical component from the storage path. That changes latency by orders of magnitude and changes what a filesystem should optimise for - and it introduces wear as a design constraint, which rotating media never had in the same way.

Invention is usually dated to around 1980 with the first public presentation in 1984 and commercialisation later in the decade. The gap between invention and market is the interesting part rather than a discrepancy.

Masuoka's flash memory work at Toshiba, presented 1984

1982 · Philips and Sony

The compact disc

Digital audio on an optical disc, standardised jointly and released in 1982, with the data-carrying CD-ROM specification following.

**The first mass-market medium that was digital end to end**, and the first time consumers encountered error correction as a product feature - a scratched disc still played, which was startling to anyone used to vinyl. It also proved that two competing manufacturers agreeing on one standard beats either of them winning.

The Red Book standard, Philips and Sony, with commercial release in 1982

1837 · Cooke and Wheatstone in Britain; Morse and Vail in the United States

The electric telegraph

Messages encoded as electrical signals and sent along a wire, arriving faster than any physical carrier could travel.

**The first separation of a message from its messenger**, and therefore the beginning of everything this site is about. It also produced the first version of a problem still with us: a shared medium, contention for it, and the need for a code that a receiver can unambiguously decode.

Cooke and Wheatstone's 1837 patent; Morse's demonstrations in the same period

1866

A working transatlantic cable

After failures in 1857 and 1858, a submarine telegraph cable between Ireland and Newfoundland that stayed in service.

Intercontinental latency drops from weeks to minutes. It is also the first time the industry learns that a long cable is not a short cable scaled up - dispersion, attenuation and the physics of a very long conductor forced the theory that made later cables possible.

The 1866 Atlantic Telegraph cable, following the failures of 1857 and 1858

1876 · Alexander Graham Bell, with contested priority

The telephone

Speech transmitted electrically, rather than a code standing in for words.

It introduced the requirement that would dominate networks for a century: a continuous, low-latency, always-available path between two points. Circuit switching exists to provide that, and packet switching exists because it turned out to be a wasteful way to carry anything but speech.

Priority is genuinely disputed - Elisha Gray filed a caveat the same day, and Antonio Meucci's earlier work is recognised by some accounts. The dispute is recorded rather than adjudicated here.

Bell's 1876 patent; Gray's same-day caveat; Meucci's earlier demonstrations

1901 · Guglielmo Marconi

Radio across the Atlantic

A signal reported received in Newfoundland from Cornwall, over a distance many believed impossible given the curvature of the earth.

It established that radio was not limited to line of sight, which nobody could then explain - the ionosphere had not been described. A working technology outrunning its own theory is a recurring pattern in this industry.

The 1901 reception has been questioned - the evidence was a faint sequence of clicks heard by ear, and later analysis has debated whether it could have been the intended signal. Subsequent transmissions were unambiguous. Recorded as reported, with the doubt noted.

Marconi's reported transatlantic reception at Signal Hill, December 1901

1958

The modem

The Bell 101, converting digital data into audible tones so it could travel over telephone lines built for speech.

**The first time digital data was carried on infrastructure designed for something else**, which is the pattern for everything since - DSL, cable, mobile data. It also sets the constraint the whole field then worked against: the telephone channel is about three kilohertz wide, and Shannon's theorem says exactly what that permits.

The Bell 101 dataset, 1958

1962

Communications by satellite

Telstar 1 relayed the first live transatlantic television pictures and telephone calls.

It established a second path between continents that owed nothing to cable, and introduced a latency floor set by the speed of light and the height of the orbit. Every argument about geostationary versus low-earth-orbit constellations is a re-run of the trade this made visible.

Telstar 1, launched July 1962

1969

The first ARPANET links

Packet-switched links between four university sites in the United States, using Interface Message Processors as the first routers.

Packet switching rather than circuit switching: the network stops reserving a path for a conversation and starts forwarding self-describing chunks independently. Everything about congestion, routing and best-effort delivery follows from that single choice.

The first four ARPANET nodes, 1969

1970 · Robert Maurer, Donald Keck and Peter Schultz, Corning

Low-loss optical fibre

Glass fibre pure enough to carry light for kilometres rather than metres, crossing the threshold below which optical transmission becomes practical.

Fibre had been understood for years and was useless because the glass was too dirty. **This is a materials achievement rather than a communications one**, and it is the reason bandwidth stopped being scarce. Almost every capacity figure elsewhere on this site rests on it.

Corning's 1970 demonstration of fibre with attenuation below 20 decibels per kilometre

1973 · Robert Metcalfe and David Boggs, Xerox PARC

Ethernet

A memo describing a broadcast network over shared coaxial cable, with stations listening before transmitting and backing off after collisions.

**The design that won, and it won by being tolerant rather than correct.** It did not guarantee delivery or fair access; it assumed collisions would happen and made recovery cheap. Modern switched Ethernet has no collisions and keeps the frame format, the addressing and the name - which is a lesson about what actually persists in a standard.

Metcalfe's 1973 memo at Xerox PARC describing the Ethernet concept

1974 · Vint Cerf and Robert Kahn

A protocol for packet network intercommunication

A design for connecting different packet networks to each other, with gateways between them and a common protocol above.

**Internetworking, as distinct from networking.** The insight is that the networks themselves need not agree on anything much, provided something above them does. That is why the internet absorbed every physical medium invented since without redesigning itself.

Cerf and Kahn, A Protocol for Packet Network Intercommunication, IEEE Transactions on Communications, 1974

1983

The ARPANET switches to TCP/IP

On 1 January 1983 the network cut over from its older host protocol to TCP/IP, with no gradual transition.

**A hard cutover on a working network, which nobody would attempt today**, and it is the moment the internet's protocol stack becomes the internet's protocol stack. It is also the best available demonstration that migrations succeed when the deadline is real and everyone has the same one.

The ARPANET TCP/IP transition, 1 January 1983

1988

The first transatlantic fibre cable

TAT-8, carrying roughly 40,000 simultaneous telephone circuits across the Atlantic on optical fibre.

Capacity per cable jumps by orders of magnitude, and the economics of long-distance traffic change permanently. Almost every argument about where data physically travels, and whose jurisdiction it passes through, dates from the fibre era beginning here.

TAT-8, the first transatlantic fibre-optic cable, in service 1988

1991 · Tim Berners-Lee, CERN

The World Wide Web made public

Hypertext over the internet, with a naming scheme, a transfer protocol and a markup language - released for anyone to implement.

The internet existed for two decades before most people had a reason to touch it. **The web is that reason**, and the decision to put it in the public domain rather than license it is why there is one web rather than several incompatible ones. Every tool on this site is delivered through it.

The World Wide Web project made publicly available in 1991; CERN's public-domain release in 1993