How the calculator
became everything

Seeing how many errors crept into tables calculated by hand, Charles Babbage designed the Difference Engine to evaluate polynomials automatically. His later Analytical Engine, with memory, an arithmetic unit and conditional branching, looks strikingly like a modern computer, but the technology of the day could not build it.

• Difference engine ↗
• Charles Babbage ↗

In notes added to her translation of a paper on the Analytical Engine, Ada Lovelace set out a procedure for computing Bernoulli numbers. She foresaw that such a machine could handle not only numbers but symbols, even music.

• Ada Lovelace ↗
• Note G ↗

Herman Hollerith stored information as holes in cards and built a machine that read and tallied them electrically, cutting the time needed to count the 1890 US census dramatically. Through mergers, his company became IBM in 1924.

• Tabulating machine ↗
• Herman Hollerith ↗

In "On Computable Numbers," Turing showed that every computation can be expressed by an imaginary machine with nothing but a tape and a table of rules. His universal Turing machine, a single machine that can imitate any other, is the theoretical foundation of every computer today.

• Turing machine ↗

In his master's thesis, MIT graduate student Claude Shannon showed that Boolean algebra could be used to design circuits of electrical switches. It has been called the most important master's thesis ever written.

• A Symbolic Analysis of Relay and Switching Circuits ↗

Built from relays in Germany, Zuse's Z3 was a fully automatic, program-controlled digital calculator. It was destroyed in a bombing raid during the war and remained little known for years.

• Z3 (computer) ↗

Built at Bletchley Park with about 1,600 vacuum tubes, Colossus was used to decrypt messages from the German High Command. Its very existence remained secret for decades after the war.

• Colossus computer ↗

A general-purpose electronic computer built to calculate artillery trajectories for the US Army, ENIAC was unveiled the following year and hailed as an "electronic brain." Reprogramming it meant days of rewiring cables and switches, work done mostly by six women programmers.

• ENIAC ↗

John von Neumann's draft report on the EDVAC laid out a design in which programs are stored in memory and fetched for execution. Instead of rewiring cables, you simply changed what was in memory, and nearly every computer still works this way.

• Von Neumann architecture ↗
• First Draft of a Report on the EDVAC ↗

Bardeen, Brattain and Shockley built a semiconductor device that could amplify and switch signals. It was smaller than a vacuum tube, used less power and rarely failed. The three shared the 1956 Nobel Prize in Physics.

• Transistor ↗

When the Harvard Mark II malfunctioned, Grace Hopper's team found a moth stuck in a relay and taped it into the logbook. The word "bug" was in use before then, but this page remains its most famous real-world example.

• Software bug ↗
• Grace Hopper ↗

A small experimental machine at the University of Manchester successfully ran a program stored in its own memory, the first proof that the von Neumann design actually worked.

• Manchester Baby ↗

First delivered to the Census Bureau, UNIVAC became famous during the 1952 presidential election when, early in the count, it correctly predicted Eisenhower's landslide. The same year in Britain, the LEO computer built by the catering company J. Lyons began running payroll.

• UNIVAC I ↗
• LEO (computer) ↗

Hopper created the A-0 system, which turned instructions written by people into machine code. At the time, many refused to believe it, insisting computers could only do arithmetic.

• A-0 System ↗
• Grace Hopper ↗

It stored about 5 MB on fifty platters and could retrieve any piece of data directly, without winding through a tape. Today a memory card the size of a fingernail holds hundreds of thousands of times as much.

• IBM 305 RAMAC ↗

FORTRAN, created by John Backus's team at IBM, let programmers write statements that looked like formulas, and it produced code as fast as hand-written machine code. It is still used for weather forecasting and physics simulations.

• Fortran ↗

Jack Kilby of Texas Instruments demonstrated it first, and the next year Robert Noyce of Fairchild introduced a planar silicon process suited to mass production. Noyce later co-founded Intel.

• Integrated circuit ↗
• Invention of the integrated circuit ↗

Influenced by Grace Hopper and developed jointly by industry and the US government, COBOL was built for business data processing. Many core systems at banks and government agencies around the world still run on it.

• COBOL ↗

MIT's CTSS sliced the computer's time so finely that many users at their own terminals could all seem to be using it at once. It marked the shift from batch processing, where you waited hours for results, to interactive computing.

• Compatible Time-Sharing System ↗

Two spaceships shot at each other on a PDP-1 computer. The game spread from lab to lab and became the first widely played video game.

• Spacewar! ↗

By letting the same software run on everything from small models to large ones, System/360 became the standard for business computing. IBM invested so much in the project that it bet the company on it.

• IBM System/360 ↗

Kemeny and Kurtz at Dartmouth College designed BASIC so that students outside science and engineering could program. A decade later it became the standard language of personal computers.

• Dartmouth BASIC ↗

Gordon Moore observed that the number of components on an integrated circuit was doubling every year (later revised to every two years). The prediction became a target the semiconductor industry set out to meet, and it held for more than half a century.

• Moore's law ↗

At about $18,000, a startlingly low price for its time, DEC's PDP-8 let labs and factories have computers of their own. A market that had held only mainframes gained a new category: the minicomputer.

• PDP-8 ↗

In 90 minutes he showed the mouse, hypertext, windows, video conferencing and real-time collaborative editing all at once. The same year, Noyce and Moore founded Intel.

• The Mother of All Demos ↗

Apollo 11's guidance computer steered the moon landing with what today seems a tiny amount of memory, and Margaret Hamilton, who led its software team, popularized the term "software engineering." The same year, Ken Thompson and Dennis Ritchie at Bell Labs began building UNIX.

• Apollo Guidance Computer ↗
• Unix ↗

A semiconductor memory chip that stores bits as charges in tiny capacitors, it was smaller and cheaper than core memory woven from magnetic rings, and it turned Intel into a memory company.

• Intel 1103 ↗
• Dynamic random-access memory ↗

Made for the Japanese calculator company Busicom, it put an entire CPU on a chip the size of a fingernail. The same year IBM introduced the 8-inch floppy disk.

• Intel 4004 ↗

Rewritten in C, UNIX became easy to move to other machines. C and UNIX went on to become the roots of Linux, macOS, Android and iOS, and C's syntax lives on in C++, Java and JavaScript.

• C (programming language) ↗

Atari's Pong was the first commercially successful arcade video game. A vast new market, the game industry, opened up.

• Pong ↗

The Alto, built at Xerox PARC, was a personal workstation with a graphical screen, a mouse and an Ethernet connection. It was never sold commercially, but a few years later it greatly inspired a visiting Steve Jobs.

• Xerox Alto ↗

Microsoft began when Bill Gates and Paul Allen wrote and sold a BASIC interpreter for the Altair 8800, the kit featured on a magazine cover. Apple's founders were active in the Homebrew Computer Club, a gathering of hobbyists.

• Altair 8800 ↗
• Altair BASIC ↗

Three ready-made personal computers, later called the "1977 Trinity," came out in a single year and opened the market. The Apple II, with its color graphics, spread quickly into schools and homes.

• Apple II ↗
• Commodore PET ↗
• TRS-80 ↗

The instruction set of Intel's 16-bit 8086 carried on through its successors and became known as "x86." More than 40 years later, most PCs and servers still use chips from this lineage.

• Intel 8086 ↗
• X86 ↗

The first spreadsheet program recalculated the whole table whenever you changed a single number. Accountants and managers bought Apple IIs just to use it.

• VisiCalc ↗

IBM built its PC quickly from off-the-shelf parts and an outside operating system, and its open design spawned countless compatible clones. Microsoft, which supplied the operating system, became the biggest winner of the PC era.

• IBM Personal Computer ↗
• MS-DOS ↗

With a low price and impressive graphics and sound, it sold an estimated 10 million units or more. A whole generation of programmers and game developers learned to code on it.

• Commodore 64 ↗

Stallman announced he would build a UNIX-compatible operating system that anyone could freely use, change and share. GNU's tools and its GPL license later combined with Linux to form the foundation of the open-source world.

• GNU Project ↗

Launched with a Super Bowl ad, the Macintosh made the graphical interface and the mouse a mass-market product. Its screen also gave rise to a new industry: desktop publishing.

• Macintosh 128K ↗
• 1984 (advertisement) ↗

Microsoft released Windows 1.0, and Britain's Acorn made the first ARM processor, a simple, low-power chip. Twenty-five years later, ARM would be the brain of almost every smartphone.

• Windows 1.0 ↗
• ARM architecture family ↗

Linus Torvalds released an operating system kernel he called "just a hobby," and developers around the world joined in. Today most servers, supercomputers and Android phones run on Linux.

• Linux ↗

Intel launched the Pentium, a chip with a name instead of a number, and built up its "Intel Inside" brand. The same year, Jensen Huang and others founded NVIDIA to make 3D graphics chips.

• Pentium (original) ↗
• Nvidia ↗

People lined up outside stores on launch day, and the Start menu and taskbar remain the basic look of Windows to this day. The PC became as easy as a household appliance.

• Windows 95 ↗

A small device for your calendar, contacts and notes, with simple handwriting recognition for a stylus. It was the prototype of the handheld computer before the smartphone.

• PalmPilot ↗

An all-in-one computer from Steve Jobs, back at an Apple on the brink of bankruptcy. By dropping the floppy drive and putting USB front and center, it played a big part in making USB the standard.

• iMac G3 ↗

NVIDIA introduced the GeForce 256, a chip dedicated to 3D processing, as "the world's first GPU." At the same time the world was busy fixing Y2K: programs that stored years as two digits and might mistake 2000 for 1900.

• GeForce 256 ↗
• Year 2000 problem ↗

Apple rebuilt its operating system on a UNIX foundation with Mac OS X, while Microsoft's Windows XP became one of the longest-lived versions of Windows, in use for more than a decade.

• Mac OS X 10.0 ↗
• Windows XP ↗

A music player with a tiny hard disk and a click wheel revived Apple and paved the way to the iPhone.

• iPod ↗

As heat made higher clock speeds impractical, Intel and AMD released processors with two cores on one chip. The same year Linus Torvalds created Git, a distributed version control system, to manage Linux development.

• Multi-core processor ↗
• Git ↗

It dropped the physical keyboard and controlled everything through a single multi-touch screen. The era of always having a computer in your hand began here.

• iPhone (1st generation) ↗

Apple opened the App Store, and Google released Android, an open-source mobile operating system. With manufacturer after manufacturer adopting Android, smartphones spread rapidly.

• Android (operating system) ↗
• App Store (Apple) ↗

The iPad brought the tablet into the mainstream. Within a few years, sales of smartphones and tablets had far overtaken PCs.

• iPad (1st generation) ↗

Created by a British foundation to teach students to code, this ultra-cheap computer found its way not only into classrooms but into hobby electronics and industrial equipment.

• Raspberry Pi ↗

When etching ever-smaller cells on a flat surface hit its limits, mass production began on 3D NAND, which stacks storage cells vertically. It made SSDs cheaper and larger, and they rapidly replaced hard disks.

• Flash memory ↗

Google revealed the TPU, a chip dedicated to neural networks that it was already using in its data centers. The trend of building chips tailored to specific tasks, beyond general-purpose CPUs and GPUs, took off.

• Tensor Processing Unit ↗

Researchers revealed that speculative execution, a technique for running instructions ahead of time to gain speed, could let one program peek at another's secret data. Almost every processor made in the previous 20 years was affected.

• Spectre (security vulnerability) ↗
• Meltdown (security vulnerability) ↗

Google announced that its 53-qubit quantum processor had far outperformed classical supercomputers on a specific calculation. The practicality of the task and the fairness of the comparison were disputed, but it became an important milestone for quantum computing.

• Quantum supremacy ↗
• Sycamore (processor) ↗

Apple dropped Intel and put the M1, an ARM-based chip descended from the iPhone's, into the Mac. Its performance and battery life reset expectations for laptops.

• Apple M1 ↗

As the pandemic drove up demand for electronics and disrupted supply chains, almost every industry, from cars to appliances, ran short of chips. Governments began treating semiconductors as a matter of national security.

• 2020–2023 global chip shortage ↗

Frontier at Oak Ridge National Laboratory became the first machine to officially reach exascale performance (10^18 operations per second). The same year the US passed the CHIPS Act, providing huge subsidies for domestic chip manufacturing.

• Frontier (supercomputer) ↗
• CHIPS and Science Act ↗

As orders poured in for the GPUs needed to train generative AI, NVIDIA became the first chipmaker worth more than a trillion dollars. High Bandwidth Memory (HBM), mounted beside the GPU, became a prized component too.

• Nvidia ↗
• High Bandwidth Memory ↗

Apple launched Vision Pro, which floats screens in front of your eyes, as a "spatial computer," while the PC industry promoted "AI PCs" with dedicated neural processing units (NPUs). The same year, NVIDIA briefly became the most valuable company in the world.

• Apple Vision Pro ↗
• Neural processing unit ↗

Google's Willow quantum chip demonstrated "below threshold" error correction: grouping more qubits together actually lowered the error rate. It is seen as a key step toward a useful quantum computer.

• Willow processor ↗