The personal computer emerged in the mid-1970s, not as a single invention but as a shift from room-sized machines to devices individuals could own and operate at home
The first computers that resembled what we call a PC today appeared between 1975 and 1977. The Altair 8800, released in January 1975, is often marked as the starting point — it was the first computer kit affordable enough for hobbyists to build themselves, costing around $400. The Apple II, launched in April 1977, was the first PC sold fully assembled and ready to use. The Commodore PET arrived the same year. These three machines defined what a personal computer meant: a device small enough to fit on a desk, affordable enough for individuals to buy, and straightforward enough for non-engineers to operate.
Before 1975, computers existed only in laboratories, universities, and large corporations. They occupied entire rooms, required specialized technicians to run them, and cost hundreds of thousands of dollars. The shift to personal computers happened because microprocessors — the chips that do the computing — became small and cheap enough to make desktop machines practical. The Intel 4004, released in 1971, was the first microprocessor. By 1975, processors had advanced enough that a hobbyist could build a working computer from a kit.
Key Takeaways
- The Altair 8800 in 1975 was the first computer kit affordable for individual hobbyists, marking the beginning of the personal computer era.
- The Apple II and Commodore PET, both released in 1977, were the first fully assembled personal computers sold to consumers.
- Personal computers became possible because microprocessors shrank in size and cost during the early 1970s, making desktop machines practical.
- Before 1975, computers were room-sized machines operated only by specialists in corporations and universities.
Why the Altair 8800 mattered in 1975
The Altair 8800 was sold as a kit — buyers received circuit boards and components and had to assemble the machine themselves. It had no keyboard, no monitor, and no permanent storage. Users entered programs by flipping switches on the front panel and read results from blinking lights. Despite these limitations, it sold thousands of units in its first year because it was the first computer a person could actually own.
The Altair's success created a market. Hobbyists began writing software for it. Two young programmers, Bill Gates and Paul Allen, wrote a version of the BASIC programming language for the Altair and founded Microsoft to sell it. Steve Jobs and Steve Wozniak saw the Altair and decided to build something better — a computer that came fully assembled with a keyboard and monitor. That decision led to the Apple II.
The Apple II changed what a personal computer could do
The Apple II, released in April 1977, was the first personal computer that looked and worked like machines people use today. It came in a plastic case, included a keyboard, connected to a television for display, and had a cassette drive for storing programs. More importantly, it ran software that ordinary people could use without programming knowledge. A spreadsheet program called VisiCalc, released in 1979, made the Apple II useful for business — accountants and small business owners could suddenly do calculations on a computer instead of by hand.
The Apple II remained the best-selling personal computer throughout the 1980s. Its success proved that people would pay for computers if the machines were straightforward to use and the software solved real problems. Apple sold millions of Apple IIs over the next decade, and the company's profits from those sales funded the development of later machines like the Macintosh.
IBM entered the market in 1981 and set the standard for business computers
IBM, the dominant computer manufacturer of the 1960s and 1970s, initially dismissed personal computers as toys. By 1981, IBM decided it needed a PC to compete with Apple. IBM released the IBM PC in August 1981. It was not the most advanced machine — the Apple II was technically superior — but IBM had something Apple did not: relationships with thousands of businesses and a reputation for reliability.
The IBM PC ran an operating system called DOS, written by Microsoft. IBM's decision to allow other companies to manufacture IBM-compatible computers meant that dozens of manufacturers could build machines that ran the same software. This openness created competition on price and features. By the mid-1980s, IBM-compatible computers outsold Apple machines in the business market, and the IBM PC standard became the dominant architecture for personal computers.
The Commodore 64 brought personal computers into homes
While Apple and IBM competed for business users, the Commodore 64, released in 1982, became the best-selling personal computer of all time by volume. It cost $595 at launch — less than half the price of an Apple II — and came with built-in sound and graphics capabilities that made it popular for games and entertainment. The Commodore 64 introduced millions of people to computing who could not afford an Apple or IBM machine.
The Commodore 64 remained in production for over a decade and sold more than 17 million units worldwide. For many people born in the 1970s and 1980s, the Commodore 64 was their first computer. It proved that personal computers did not have to be expensive or business-focused to succeed — they could be affordable, fun, and accessible to ordinary households.
What made personal computers different from earlier machines
The computers that existed before 1975 were mainframes — large machines that occupied entire rooms and served many users at once through terminals. A mainframe cost millions of dollars and required a staff of technicians to operate and maintain. Only large corporations, universities, and government agencies could afford them. Computing was something that happened in a specialized facility, not something an individual could do at home.
Personal computers inverted this model. They were designed for one person to own and operate alone. They were small enough to fit on a desk or in a home office. They were affordable enough that a person could save up and buy one. They required no special training — a person could read a manual and learn to use one. This shift from centralized, specialized computing to individual, accessible computing changed not just technology but society itself.
The timeline from invention to mainstream adoption
The personal computer did not become mainstream overnight. The Altair 8800 in 1975 reached hobbyists and engineers. The Apple II and Commodore PET in 1977 reached early adopters with more money. The IBM PC in 1981 convinced businesses that personal computers were serious tools. The Commodore 64 in 1982 brought prices low enough that middle-class families could afford one. By the mid-1980s, personal computers were common in offices and homes.
The graphical user interface — the system of windows, icons, and a mouse that modern computers use — did not appear until the Macintosh in 1984 and the IBM PC with Windows in 1985. These machines made computers easier to use for people who had never programmed. By 1990, personal computers had become ordinary consumer products, and the era of room-sized mainframes was ending.
Frequently Asked Questions
Who invented the personal computer?
No single person invented the personal computer. The Altair 8800 was designed by Ed Roberts and Henry Yuen. Steve Jobs and Steve Wozniak built the Apple II. IBM assembled a team to create the IBM PC. The personal computer emerged from the work of many engineers and entrepreneurs working in the mid-1970s.
Was the Apple II really the first personal computer?
No. The Altair 8800 came first in January 1975, but it was a kit that required assembly and had no keyboard or monitor. The Apple II in April 1977 was the first fully assembled, ready-to-use personal computer. Both are considered foundational machines in the history of personal computing.
Why did IBM's personal computer become so dominant?
IBM allowed other manufacturers to build computers compatible with the IBM PC standard and did not control the supply of key components. This openness created competition and drove down prices. IBM's existing relationships with businesses also gave the IBM PC credibility in corporate environments where the Apple II had already gained ground.
How much did the first personal computers cost?
The Altair 8800 kit cost around $400 in 1975, which is roughly $2,000 in equivalent dollars from a decade later. The Apple II cost $1,298 in 1977. The IBM PC cost $1,565 in 1981. The Commodore 64 cost $595 in 1982, making it the most affordable option for home users.
What software made early personal computers useful?
VisiCalc, a spreadsheet program released in 1979 for the Apple II, was the first process that made personal computers valuable for business. WordStar, a word processor, followed. Games were also important — they drove sales of the Commodore 64 and other home computers. Without useful software, personal computers would have remained hobbyist devices.