The Software That Made Computers Think
In 1974, Gary Kildall wrote CP/M (Control Program for Microprocessors) in his kitchen while his wife Dorothy handled the business side. This 4-kilobyte program became the first commercially successful operating system for microcomputers, running on Intel 8080 processors and costing $70.
CP/M could manage files, execute programs, and interface with hardware, tasks that seem basic now but were groundbreaking when computers were glorified calculators.Kildall's creation would inadvertently shape the entire personal computing industry, though not in the way he expected.Before CP/M, every computer program had to be written for specific hardware. Programmers spent more time figuring out how to make their software talk to disk drives and printers than solving actual problems. CP/M changed this by providing a standardized interface between software and hardware. WordStar, dBase, and hundreds of other programs could run on any CP/M machine regardless of the manufacturer. This standardization created the first real software market, where programs could be mass-produced and sold to thousands of users.
The computing landscape shifted dramatically in 1980 when IBM approached Microsoft for an operating system for their upcoming Personal Computer. Bill Gates didn't have one, but he knew someone who did. He bought QDOS (Quick and Dirty Operating System) from Seattle Computer Products for $50,000 and renamed it MS-DOS. This single transaction would make Microsoft the most valuable company in the world within two decades. MS-DOS 1.0 was essentially a CP/M clone with a different command structure, but it had one crucial advantage: it came pre-installed on IBM PCs.
MS-DOS evolved rapidly through the 1980s, each version adding capabilities that seem mundane today but were essential then. DOS 2.0 introduced subdirectories, allowing users to organize files in folders instead of having everything in one giant list. DOS 3.0 added network support, enabling multiple computers to share resources. By DOS 5.0 in 1991, the system could manage extended memory, run multiple programs through task switching, and included a basic text editor. The command line interface, with its cryptic commands like "dir," "copy," and "del," became the universal language of personal computing.
While Microsoft dominated the PC market, other operating systems were pushing boundaries elsewhere. Unix, developed at Bell Labs in 1969, was running on powerful workstations and servers. Unix introduced concepts that modern operating systems still use: multi-user environments, file permissions, and a hierarchical file system. Its philosophy of "do one thing and do it well" influenced generations of programmers. Unix systems cost tens of thousands of dollars but offered capabilities that PCs wouldn't match for years: true multitasking, network transparency, and rock-solid stability.
The graphical user interface era began with systems like the Xerox Star in 1981, but it was Apple's Lisa in 1983 and later the Macintosh in 1984 that brought GUIs to a broader audience. The Macintosh System 1.0 fit on a single 400KB floppy disk and introduced millions to the concept of windows, icons, and the mouse. Users could point and click instead of memorizing commands. Files looked like documents, and the trash can actually looked like a trash can. This visual metaphor made computers accessible to people who weren't programmers.
Microsoft's response came with Windows 1.0 in 1985, but it was more of a graphical shell running on top of DOS than a true operating system. Windows didn't gain real traction until version 3.0 in 1990, which could finally run multiple programs simultaneously and manage memory efficiently. Windows 3.1, released in 1992, became the first Windows version to outsell DOS, marking the beginning of the end for command-line interfaces in mainstream computing.
Network operating systems emerged as businesses began connecting their computers. Novell NetWare, launched in 1983, became the dominant network OS by focusing purely on file and print sharing. NetWare servers could handle hundreds of simultaneous users accessing shared databases and applications. The system was so reliable that many NetWare servers ran for years without rebooting. Network administrators became high priests of connectivity, managing user accounts, disk quotas, and backup schedules from central consoles.
OS/2, IBM's ambitious attempt to create a next-generation operating system, launched in 1987 with advanced features like preemptive multitasking and a 32-bit architecture. OS/2 was technically superior to Windows in many ways, but it came too late and cost too much. The system could run DOS and Windows programs better than Windows itself, but without significant software written specifically for OS/2, it remained a niche product despite IBM's massive marketing efforts.
The early 1990s brought Windows NT (New Technology), Microsoft's first truly modern operating system. NT was designed from the ground up with security, stability, and networking in mind. It featured preemptive multitasking, memory protection, and a robust security model. NT could run on different processor architectures and handle server duties as well as desktop work. The system was complex and resource-hungry, requiring at least 16 MB of RAM when most PCs had 4 MB, but it laid the foundation for all future Windows versions.
Unix variants proliferated throughout the 1980s and 1990s, with each vendor adding proprietary features. Sun Microsystems' SunOS, IBM's AIX, and HP's HP-UX dominated the workstation market. These systems powered early web servers, database systems, and computer-aided design workstations. Unix's networking capabilities, built-in from the beginning, made it the natural choice for the servers that would eventually run the internet.
The command line versus graphical interface debate raged throughout the 1980s and 1990s. Experienced users argued that command lines were faster and more powerful, while newcomers preferred the intuitive nature of graphical interfaces. Both sides were right. Power users could accomplish complex tasks with a few keystrokes, while casual users could be productive without memorizing arcane commands. The best systems provided both options, allowing users to choose their preferred interface.
Looking back, these operating systems established principles that still govern computing today: standardized hardware interfaces, multitasking, networking, and user-friendly interfaces. Modern operating systems like Windows 11, macOS, and Linux are direct descendants of these early systems. The concepts pioneered by CP/M, refined by DOS, and perfected by Unix form the foundation of every smartphone, tablet, and server running today. Without these early operating systems managing hardware resources and providing programming interfaces, there would be no platform for the artificial intelligence algorithms and robotic control systems that define current technology.
