---
title: Personal Computer Revolution
tags: [personal-computer, apple, ibm, microprocessor]
status: active
confidence: high
created: 2026-04-09
sources:
  - file: public-domain/ceruzzi-history-modern-computing.txt
    hash: placeholder
    size: 0
    ingested: 2026-04-09
aliases: []
---

# Personal Computer Revolution

The personal computer revolution of the 1970s and 1980s brought computing from air-conditioned mainframe rooms into homes and small businesses, fundamentally democratising access to programmable machines.

## The Altair 8800 (1975)

MITS's Altair 8800, sold as a kit for $439, is the symbolic starting point of the PC era. Based on Intel's 8080 processor, it had no keyboard and no display — users toggled binary switches on the front panel. Despite this, it sold thousands of units and triggered a hobbyist ecosystem. Critically, it attracted two Harvard students — Bill Gates and Paul Allen — who wrote a BASIC interpreter for it and founded Microsoft.

## Apple II (1977)

Steve Wozniak designed the Apple II around the MOS 6502 processor. It was the first mass-market computer with a colour display, an open expansion bus, and a plastic case designed for a home environment. VisiCalc (1979), the first spreadsheet, ran on the Apple II and became the first "killer app" — people bought the computer to run the software, not the other way around.

## IBM PC and the Open Architecture (1981)

IBM's decision to build the PC from off-the-shelf parts and publish the technical specifications was the most consequential business decision of the era. It licensed the operating system from Microsoft (MS-DOS) and the CPU from Intel. Within two years, dozens of manufacturers cloned the platform legally, creating a commodity hardware market. The architecture — x86 CPU, BIOS, DOS — became the default standard and still underlies most Windows machines today.

## Graphical User Interface

Xerox PARC developed the first practical GUI with the Alto (1973), but it was Apple's Macintosh (1984) that brought windows, icons, and a mouse to a mainstream audience. Microsoft followed with Windows 1.0 (1985). The GUI made [[programming-languages-overview]] tools accessible to users who would never write code.

## Relationship to Other Pages

The personal computer runs on [[von-neumann-architecture]] hardware. Its operating systems descend from [[unix-history]] (macOS, Linux desktop) or from the DOS/Windows lineage. The [[transistor-and-microchip]] revolution made the microprocessors that power PCs possible. The [[internet-origins]] web gave PCs their "always-on" purpose in the 1990s.
