The ENIAC was the first electronic computer, but the Altair 8800 was the first personal computer you could buy
The answer depends on what you mean by "personal computer." ENIAC, built in 1946 at the University of Pennsylvania, was the first general-purpose electronic computer — but it weighed 30 tons, filled a room, and cost the equivalent of roughly $10 million in today's money. Nobody owned one.
The first computer ordinary people could actually purchase was the Altair 8800, released in January 1975 by MITS (Micro Instrumentation and Telemetry Systems). It cost $397 for the kit version (you assembled it yourself) or $498 fully built. It had no monitor, no keyboard, and no storage — just switches and lights. But it was the machine that made "personal computer" a real category.
Between those two dates, the technology shrank from room-sized to desktop-sized, and the price fell from millions to hundreds. That shift happened because of the microprocessor — a single chip that could do what earlier computers needed an entire building to accomplish.
Key Takeaways
- ENIAC (1946) was the first electronic computer, but it was a research machine the size of a room that no individual could own or operate.
- The Altair 8800 (1975) was the first personal computer available for purchase, costing under $500 and marking the start of the home computer era.
- The microprocessor made personal computers possible by shrinking computing power from room-sized equipment to a single chip small enough to fit on a desktop.
- Apple II (1977) and Commodore 64 (1982) brought personal computers into homes by adding a monitor, keyboard, and usable software.
- The IBM PC (1981) established the standard that most computers still follow today, including the operating system model and hardware architecture.
How ENIAC changed computing but was not a personal computer
ENIAC stood for Electronic Numerical Integrator and Computer. It used 18,000 vacuum tubes instead of transistors or chips, and those tubes generated so much heat that the machine needed its own cooling system. It ran on 150 kilowatts of electricity — roughly what 150 homes use today.
ENIAC was built to solve a specific military problem: calculating artillery firing tables during World War II. After the war ended, it stayed at the University of Pennsylvania and was used for scientific research. Only a handful of people in the world knew how to operate it, and only institutions with massive budgets could afford to build or run one.
ENIAC proved that electronic computing worked, but it was not personal in any sense. You did not own it, you did not operate it yourself, and you could not move it. It was a tool for institutions, not individuals.
The microprocessor made the Altair 8800 possible
In 1971, Intel released the 4004, the first microprocessor — a single chip that contained all the computing power that earlier machines needed thousands of components to achieve. By 1974, the Intel 8008 and then the 8080 made it practical to build a computer small enough to sit on a desk.
MITS saw the opportunity and designed the Altair 8800 around the Intel 8080. The machine came as a kit: you soldered components onto a circuit board, plugged in the processor, and powered it on. There was no screen — you toggled switches on the front panel to input data and read the results from a row of lights. There was no storage except a cassette tape drive you could add later.
But it worked, it was affordable, and it was yours. Hobbyists and engineers bought thousands of them. The Altair 8800 created a market where none had existed before.
Apple II and Commodore 64 brought personal computers into homes
The Altair 8800 was a hobbyist machine. It required technical knowledge to use and offered no built-in software. The Apple II, released in 1977, changed that. It came with a keyboard, a monitor port, and a cassette drive for storage. More importantly, it shipped with software already installed, including a spreadsheet program called VisiCalc.
The Apple II cost $1,298 fully configured — expensive, but within reach of small businesses and affluent families. It became the first personal computer to sell in large numbers to non-technical users.
The Commodore 64, released in 1982, brought the price down further. At $595, it was affordable for middle-class households. It had a color display, a keyboard, and a library of games and productivity software. The Commodore 64 became the best-selling computer model of all time, with an estimated 17 million units sold.
The IBM PC set the standard that still exists today
In August 1981, IBM released the IBM PC. IBM was a mainframe company — they made huge computers for corporations. The PC was their entry into the personal computer market, and they built it using off-the-shelf components rather than designing everything from scratch.
The IBM PC ran an operating system called MS-DOS, made by a small company called Microsoft. IBM licensed the operating system but did not require exclusivity, which meant other manufacturers could build computers that ran MS-DOS too. This decision shaped the entire industry.
Within a few years, IBM-compatible computers from other makers (Compaq, Dell, and others) outnumbered IBM's own machines. The architecture IBM chose — the way the processor, memory, and storage connected — became the standard. Most computers today, including the one you are using now, still follow the IBM PC architecture from 1981.
The timeline from ENIAC to the modern era
| Year | Computer | Key Detail |
|---|---|---|
| 1946 | ENIAC | First electronic computer; 30 tons; room-sized; research only |
| 1971 | Intel 4004 | First microprocessor; made personal computers possible |
| 1975 | Altair 8800 | First personal computer for sale; $397 kit version; hobbyist market |
| 1977 | Apple II | First personal computer for non-technical users; included software |
| 1981 | IBM PC | Set the standard architecture still used today; ran MS-DOS |
| 1982 | Commodore 64 | Best-selling computer model ever; brought price down to $595 |
Why the definition of "first" matters
When people ask when the first personal computer was built, they usually mean one of three things: the first electronic computer (ENIAC, 1946), the first computer you could buy (Altair 8800, 1975), or the first computer that ordinary people actually used (Apple II, 1977).
ENIAC is the historical answer if you care about the invention of electronic computing. The Altair 8800 is the answer if you care about when personal computers became a product category. The Apple II is the answer if you care about when computers entered everyday life.
All three are correct, depending on what question you are really asking. The Altair 8800 is usually called the first personal computer because it was the first one sold to individuals, even though most people could not actually use it without technical training.
Frequently Asked Questions
Did anyone else build a computer before ENIAC?
Earlier machines existed — the Analytical Engine (designed by Charles Babbage in the 1800s) and the Z3 (built by Konrad Zuse in Nazi Germany in 1941) — but ENIAC was the first general-purpose electronic computer that actually worked and was used for real calculations. The Analytical Engine was never fully built, and the Z3 was destroyed in World War II.
Could you actually do anything useful with an Altair 8800?
Yes, but only if you knew how to program it. You could write straightforward programs in a language called BASIC and store them on cassette tape. Most people who bought one were engineers or hobbyists who wanted to learn how computers worked. It was not a tool for everyday tasks like word processing or email.
Why did the IBM PC become the standard instead of the Apple II?
IBM's decision to use off-the-shelf components and license MS-DOS to other manufacturers meant that many companies could build IBM-compatible computers. Apple kept tight control over their design, so only Apple could make Apple computers. The open approach won out in the market, and IBM-compatible architecture became dominant in business and eventually in homes too.
What happened to the Commodore 64?
The Commodore 64 was hugely popular in the 1980s, especially in Europe, but IBM-compatible computers running Windows eventually took over the market. Commodore went out of business in 1994. The Commodore 64 is now considered a classic and is remembered fondly by people who grew up with it, but no new ones are manufactured.
Is there a difference between a personal computer and a PC?
"Personal computer" is a general term for any computer designed for individual use. "PC" originally meant any personal computer, but today it usually refers specifically to computers running Windows or Linux on IBM-compatible architecture. Macs are personal computers but not PCs in the modern sense.