The PC emerged in the mid-1970s, not as a single invention but as a shift from room-sized machines to devices that fit on a desk

The personal computer did not have one invention date. Instead, several machines arrived within a few years of each other in the mid-1970s, each claiming to be "first" depending on how you define personal computer. The Altair 8800, released in January 1975, is often called the first true PC because it was the first to be sold as a kit to hobbyists and small businesses. The Apple II, released in April 1977, was the first to come fully assembled and ready to use out of the box. The Commodore PET and TRS-80 both arrived later in 1977 and competed fiercely with the Apple II.

Before 1975, computers existed only in laboratories, universities, and large corporations. They occupied entire rooms, cost hundreds of thousands of dollars, and required trained operators. The shift to personal computers meant that individuals and small organizations could own and operate their own machines. This change happened because microprocessors—the chips that run computers—became small and cheap enough to put into a box you could place on a desk.

Key Takeaways

  • The Altair 8800 (January 1975) was the first personal computer sold to the public, though it required assembly and programming knowledge.
  • The Apple II (April 1977) was the first fully assembled PC ready to use, which made personal computers accessible to people without technical training.
  • The Commodore PET and TRS-80 also launched in 1977 and competed with Apple for early market dominance.
  • Personal computers became possible because microprocessors dropped in price and size during the early 1970s, making desktop machines affordable.
  • The shift from room-sized mainframes to personal computers took place over roughly two years, between 1975 and 1977.

The Altair 8800: The First Personal Computer Kit

The Altair 8800 arrived in January 1975 as a kit sold through Popular Electronics magazine for $395. Buyers received a metal box, a circuit board, and components they had to solder together themselves. The machine had no keyboard, no screen, and no storage—you entered data by flipping switches on the front panel and read results from blinking lights. Despite these limitations, it sold thousands of units to hobbyists and engineers who wanted to own a computer.

The Altair's success proved there was a market for personal computers. Two young programmers named Bill Gates and Paul Allen saw the Altair and wrote a version of the BASIC programming language for it, which led to the founding of Microsoft. The Altair showed that computers did not have to be locked away in corporate data centers—they could be personal tools.

The Apple II: The First Consumer-Ready Personal Computer

The Apple II launched in April 1977 and changed what a personal computer could be. Unlike the Altair, the Apple II came fully assembled, with a keyboard and the ability to connect to a television as a display. It had a cassette drive for storage and came with BASIC programming language built in. The price was $1,298, which was expensive but within reach of small businesses and affluent hobbyists.

The Apple II's design made computing accessible to people who did not want to build their own machine or learn assembly language. It came with a manual written for non-technical users and software that made it useful for real tasks like spreadsheets and word processing. The Apple II remained in production for 16 years and became the best-selling personal computer of the 1970s and 1980s.

The Commodore PET and TRS-80: Competing Visions

In the same year as the Apple II, Commodore Business Machines released the Commodore PET (Personal Electronic Transactor) in August 1977. The PET was also fully assembled and came with a built-in screen and keyboard—all in one unit. It cost $595, making it cheaper than the Apple II, and it appealed to schools and small offices.

The Radio Shack TRS-80 (Tandy Radio Shack Model 80) launched in August 1977 as well. Radio Shack sold it through its retail stores across the United States, which gave it a distribution advantage over Apple and Commodore. The TRS-80 cost $599 and also came fully assembled. These three machines—Apple II, Commodore PET, and TRS-80—became the dominant personal computers of the late 1970s and early 1980s, each with its own loyal user base.

Why the Mid-1970s Was the Turning Point

Personal computers became possible because of advances in microprocessor technology. The Intel 4004, released in 1971, was the first microprocessor—a single chip that could perform the functions of a much larger computer. By 1975, microprocessors had become fast enough and cheap enough that manufacturers could build complete computers around them for under $400.

At the same time, memory chips (RAM) dropped in price, and floppy disk drives became small and affordable enough to include in a desktop machine. These three pieces—a fast microprocessor, affordable memory, and reliable storage—made the personal computer practical. Before 1975, these components were too expensive or too large. After 1975, they were not.

The IBM PC and the Shift to Business Computing

In August 1981, IBM released the IBM PC, which was designed for business use rather than hobbyists. The IBM PC cost $1,565 for a basic model and ran an operating system called MS-DOS, which Microsoft had developed. IBM's entry into the personal computer market gave the industry credibility with large corporations and government agencies that had been skeptical of small computers.

The IBM PC's design was open—other manufacturers could build compatible machines using the same processor and operating system. This openness led to a flood of IBM-compatible computers from companies like Compaq, Dell, and Gateway. By the mid-1980s, IBM-compatible machines running MS-DOS had become the dominant personal computers in offices and businesses, while Apple remained strong in education and creative fields.

How Personal Computers Changed Work and Home Life

Before personal computers, most office work required typewriters, filing cabinets, and paper. Word processing software made it possible to edit and revise documents on screen. Spreadsheet software, pioneered by VisiCalc on the Apple II in 1979, let accountants and financial analysts perform complex calculations in minutes instead of hours. Email and networking, which arrived in the 1980s, changed how people communicated.

In homes, personal computers started as toys and tools for hobbyists but gradually became household items. By the 1990s, personal computers were used for homework, entertainment, banking, and shopping. The shift from mainframe computers owned by institutions to personal computers owned by individuals and families fundamentally changed how technology shaped daily life.

Frequently Asked Questions

Was the Apple II really the first personal computer?

No—the Altair 8800 came first in January 1975. However, the Apple II (April 1977) was the first fully assembled, ready-to-use personal computer. The Altair required buyers to assemble it and program it themselves, while the Apple II worked out of the box. Both claims to "first" are technically correct depending on how you define personal computer.

What did the first personal computers cost?

The Altair 8800 kit cost $395 in 1975. The Apple II cost $1,298 in 1977. The Commodore PET and TRS-80 cost around $595 to $599. Adjusted for inflation, these prices are roughly three to four times higher in current dollars, so a $1,298 Apple II in 1977 would cost around $6,000 in equivalent purchasing power.

Could you actually do useful work on early personal computers?

Yes, but only after software was written for them. The Apple II became useful for business when VisiCalc (a spreadsheet program) arrived in 1979. Word processing software followed. The IBM PC became useful for business when ready because MS-DOS and business software were available from day one. Early Altairs and Commodore PETs were mostly used by hobbyists and programmers.

Why did IBM enter the personal computer market so late?

IBM dominated the mainframe computer business and did not see personal computers as a threat at first. By 1980, it became clear that personal computers were becoming serious business tools. IBM rushed the IBM PC to market in 1981 to compete. IBM's late entry actually helped the industry because IBM's reputation made corporations take personal computers seriously.

What happened to the Commodore and early Apple computers?

The Commodore PET faded as IBM-compatible computers became dominant in business. Commodore later released the Commodore 64, which became the best-selling personal computer of all time, but mainly as a home computer and gaming machine. Apple survived by focusing on education and creative professionals. Most other early PC makers disappeared as IBM-compatible machines became the industry standard.