Personal computers evolved from hobbyist kits costing $439 in 1975 to essential tools used by approximately 4 billion people today. This guide covers every defining machine and milestone in personal computer history, from the Altair 8800 through the current PC market, with precise dates and specifications.
What Is a Personal Computer?
A personal computer is a general-purpose microprocessor-based computer designed for use by one person at a time, at a price point affordable to individuals. Three criteria define the personal computer: single-user operation, affordability for individuals (not just institutions), and general-purpose programmability. Mainframes and minicomputers failed the first two criteria before 1975.
Pre-PC Era: Why Individuals Could Not Own Computers Before 1975
Before 1975, computers were institutional machines. The IBM System/360 Model 30 (1964) cost $133,000 to purchase ($1.27 million in 2024 dollars) or $5,330 per month to lease.
The PDP-8 minicomputer (1965), the cheapest computer available, cost $18,500. Both required dedicated facilities, trained operators, and institutional budgets.
No individual could own or personally operate these machines. Computing time was rented in fractions of hours on shared systems. The microprocessor, specifically the Intel 8080 (1974), changed this by reducing CPU cost to under $400.
Altair 8800: The First Personal Computer (January 1975)
The Altair 8800 appeared on the cover of Popular Electronics in January 1975, designed by Ed Roberts of MITS (Micro Instrumentation and Telemetry Systems). It is the first machine meeting all three personal computer criteria.
Altair 8800 specifications:
- Processor: Intel 8080, 2 MHz
- RAM: 256 bytes (expandable)
- Price: $439 kit (assembled version: $621)
- Storage: none standard — no keyboard, no display
- Input: front panel toggle switches
- Output: front panel LEDs
- Units sold: approximately 5,000 in the first year
Bill Gates and Paul Allen wrote a BASIC interpreter for the Altair 8800 in 1975 — the founding product of Microsoft. The Altair’s open bus (S-100 bus) allowed third-party expansion cards, establishing the hardware expansion ecosystem that defines PCs.
Apple I and Apple II: Computing for Non-Hobbyists (1976–1977)
Steve Wozniak designed the Apple I in 1976. Unlike the Altair, it included a built-in video interface, eliminating the need for a separate terminal.
Apple I specifications:
- Processor: MOS 6502, 1 MHz
- RAM: 4KB (expandable to 48KB)
- Price: $666.66
- Units sold: approximately 200
The Apple II (June 1977) was the first personal computer designed for mass-market consumers, not hobbyists. It included color graphics, a keyboard, and a power supply in a complete unit.
Apple II impact:
- VisiCalc spreadsheet (1979) — first killer app for any personal computer; drove Apple II sales to businesses
- Cumulative Apple II sales: approximately 6 million units through 1993
- Price at launch: $1,298 (4K RAM model)
IBM PC: Open Architecture and the Clone Industry (August 1981)
IBM released the IBM Personal Computer (Model 5150) on August 12, 1981. IBM deliberately used off-the-shelf components and published the hardware specifications — a decision that created the PC clone industry.
IBM PC 5150 specifications:
- Processor: Intel 8088, 4.77 MHz
- RAM: 16KB standard (expandable to 640KB)
- Storage: optional 5.25-inch floppy drive, 160KB
- OS: MS-DOS 1.0
- Price: $1,565 base configuration
- Display: monochrome text, optional color graphics
IBM’s open architecture enabled Compaq to release the first IBM-compatible clone in 1982. By 1986, PC clone manufacturers sold more units than IBM. By 1995, the clone industry had created an ecosystem of over 1,000 compatible manufacturers.
Apple Macintosh: First Mass-Market GUI PC (January 1984)
Apple released the Macintosh 128K on January 24, 1984. It was the first mass-market personal computer with a graphical user interface and mouse as standard equipment.
- Processor: Motorola 68000, 8 MHz
- RAM: 128KB
- Storage: 400KB 3.5-inch floppy drive
- Display: 512 × 342 pixels, 9-inch monochrome built-in
- Price: $2,495
Windows Dominance: 1990s
Microsoft Windows versions drove PC adoption through the 1990s on IBM-compatible hardware:
- Windows 3.1 (1992): sold 3 million copies in 2 months; first widely adopted Windows version
- Windows 95 (1995): introduced Start menu, taskbar, 32-bit multitasking; sold 7 million copies in 5 weeks
- Windows 98 (1998): USB support, Internet Explorer integration
- Windows XP (2001): stable NT kernel for consumers; reached 400 million licenses by 2004
By 1995, Windows held approximately 90% of the desktop OS market. The PC installed base grew from approximately 2 million units (1981) to 500 million units (2000).
Laptop Era and Mobile Computing
IBM released the ThinkPad 700C in October 1992 — the defining early laptop with a 10.4-inch color TFT display, 25 MHz 486 processor, and the TrackPoint pointing device. Price: $4,350.
Laptop market milestones:
- 2008: netbooks (Asus Eee PC 900) — sub-$400, 9-inch screen, solid-state storage — peak unit sales of 35 million in 2010
- 2011: Intel Ultrabook standard — under 21mm thick, SSD required, under $1,000
- 2012: Microsoft Surface Pro — first mainstream 2-in-1 tablet/laptop hybrid
- 2020: Apple M1 MacBook Air — ARM-based laptop, 18-hour battery life, fanless design
Personal Computer Market: Key Milestones Table
| Year | Machine | Key Spec | Price | Significance |
|---|---|---|---|---|
| 1975 | Altair 8800 | Intel 8080, 256B RAM | $439 kit | First personal computer |
| 1976 | Apple I | MOS 6502, 4KB RAM | $666.66 | First with built-in video interface |
| 1977 | Apple II | 1 MHz, color graphics | $1,298 | First mass-market consumer PC |
| 1981 | IBM PC 5150 | 8088, 16KB RAM, MS-DOS | $1,565 | Open architecture; created clone industry |
| 1984 | Apple Macintosh 128K | 68000, 128KB, GUI | $2,495 | First mass-market GUI PC |
| 1992 | IBM ThinkPad 700C | 486, color TFT, TrackPoint | $4,350 | Defining early laptop design |
| 1995 | Windows 95 PC era | 32-bit, Start menu | Various | Windows at 90% desktop market share |
| 2012 | Microsoft Surface Pro | Core i5, 2-in-1 form factor | $899 | First mainstream tablet-laptop hybrid |
| 2020 | Apple M1 MacBook Air | ARM, 8-core CPU, 18hr battery | $999 | ARM transition; defined thin-and-light |
PC Gaming: A Distinct Market Segment
Dedicated gaming PCs emerged as a significant market in the 2010s with NVIDIA’s GeForce RTX series (2018) introducing real-time ray tracing.
- PC gaming revenue (2023): $38.7 billion globally (Newzoo)
- NVIDIA RTX 4090 (2022): 76.3 teraFLOPS FP32, 24GB GDDR6X — $1,599
- Steam peak concurrent users (2024): 37.7 million players
- Gaming PC share of total PC shipments: approximately 20% by revenue
Current PC Market (2024)
The global PC installed base reached approximately 1.6 billion units in 2024 per Statista. Annual PC shipments:
- 2021 (peak, pandemic demand): 348.8 million units shipped (Gartner)
- 2023: 241.8 million units shipped (IDC)
- Market share by vendor (Q4 2023): Lenovo 24.5%, HP 21.6%, Dell 16.4%, Apple 9.2%, ASUS 6.8%
Last Thoughts on the History of Personal Computers
The personal computer went from a $439 hobbyist kit with 256 bytes of RAM in 1975 to a market of 1.6 billion devices in 2024. The defining structural shift was IBM’s open architecture in 1981 — a single business decision that created a clone industry and made the PC a commodity. The current era is defined by the ARM transition (Apple M-series), AI-accelerated hardware, and a stable installed base that shifts form factor more than function.
Key Takeaways
- The Altair 8800 (January 1975) was the first personal computer: $439 kit, Intel 8080, 256 bytes RAM, no keyboard or display.
- Apple II (1977) drove business adoption via VisiCalc — the first spreadsheet; cumulative sales reached approximately 6 million units.
- IBM’s open architecture PC (1981) at $1,565 created the clone industry; over 1,000 compatible manufacturers existed by 1995.
- Windows reached approximately 90% desktop market share by 1995 on IBM-compatible hardware.
- The global PC installed base stands at approximately 1.6 billion units as of 2024 per Statista.
- Annual PC shipments peaked at 348.8 million units in 2021 (pandemic demand); normalized to 241.8 million in 2023.
What was the first personal computer?
The Altair 8800 (January 1975) is recognized as the first personal computer. It used an Intel 8080 processor, had 256 bytes of RAM, cost $439 as a kit, and had no keyboard or display.
How much did the first Apple computer cost?
The Apple I (1976) sold for $666.66 and approximately 200 units were sold. The Apple II (1977) launched at $1,298 and became the first mass-market consumer PC with color graphics.
When did the IBM PC launch?
IBM released the Personal Computer Model 5150 on August 12, 1981. It used an Intel 8088 at 4.77 MHz, 16KB RAM, and MS-DOS 1.0. The base price was $1,565.
How many personal computers exist in the world?
The global PC installed base reached approximately 1.6 billion units in 2024 per Statista. Annual shipments in 2023 were 241.8 million units per IDC.
What is the best-selling PC brand?
Lenovo held the largest PC market share at 24.5% in Q4 2023, followed by HP at 21.6% and Dell at 16.4%, per IDC quarterly PC shipment data.
