Gary Kildall, The Story of The Forgotten Genius Who Invented the PC Operating System

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Gary Kildall, Father Of The Operating System

Gary Kildall was one of the early pioneers of personal computing. Before he wrote CP/M, the first PC operating system, professional work on a personal computer workstation was unimaginable—and far too expensive. Kildall's work was revolutionary, laying the foundations for software development as we know it today. He played a crucial role in the rapid rise of microelectronics in the 1970s, a time when the potential of personal computing was just beginning to be realized, before being overtaken—and outmaneuvered—by Bill Gates and Microsoft in the 1980s.

Despite his academic struggles, Gary Kildall's resilience shone through. As a poor student, he faced the daunting task of repeating a year at Queen Anne High School in Seattle due to failing grades in English, his native language. However, a stroke of luck in the form of his desk neighbor, Dorothy McEwen, who matched him in intellect and wit, changed his life. The two were quickly separated in class for talking too much, but they stayed together long after—as husband and wife.

After school, Kildall initially followed in his father's and grandfather's footsteps, becoming an instructor at Kildall's College of Nautical Knowledge, where he trained future naval officers. However, he soon realized that other topics interested him more, so he decided to study at the University of Washington despite his poor grades.

Beating the Odds

Against all odds, he was accepted and transformed into a straight-A student through hard work. His early mathematical training from family schooling helped. Since calculations were no longer done solely with mechanical tools, he had his first encounter with computers in 1964—and found his life's calling. Kildall's resilience and determination in the face of academic challenges and financial constraints are a testament to his character and played a significant role in shaping his future success.

Working on a room-sized Burroughs, Kildall discovered his passion for compiler programs, which translate user inputs into machine-readable code. Assigned to maintain the computer, he hung a 'Maintenance Work' sign between midnight and 6 AM—during which time the machine was his alone. His dedication and passion for computing paid off, leading him to become one of the first graduates of the University of Washington's computer science program.

His dedication paid off. He became one of the first graduates of the University of Washington's computer science program. His thesis focused on the mathematical principles of code optimization, the foundation of every compiler. Kildall was among the few people at the time who understood both the practical workings of computers and the theoretical foundations for improving them.

But one thing he didn't have? His own computer.

Despite his privileged access to the university's mainframe, his time on it was limited. That changed when he learned about the first commercially available microprocessor. Unfortunately, the chip—and the programming hardware needed—were still far too expensive for his meager assistant professor's salary.

The Intel 4004 CPU was supposed to cost just $1,000, plus another $700 for a Teletype input device. (Monitors weren't standard in the early 1970s.)

Kildall's innovative approach to problem-solving was evident when he found a way to simulate the Intel 4004 on his work computer, an IBM 370, and began writing programs without ever touching the actual chip. His resourcefulness and creativity impressed an Intel employee, leading to Kildall receiving his own CPU and hardware, as well as a consulting job with the rising company.

The First Personal Computer

By 1972, he had assembled a portable computer from a mess of circuit boards, cables, and rewritable memory chips—one he could take to demonstrations. Always in tow was the 30-kilogram Teletype monster, without which no input or output was possible.

At the time, Intel was unconvinced by personal computing or the software business. When Kildall showed an Intel executive a game he'd programmed for his blinking contraption, the man dryly remarked that the future lay in digital watches, not computer games.

Kildall spent more time trading his programming skills for Intel hardware. But when the chipmaker finally recognized its technology's potential in 1976, their visions diverged.

Kildall was an idealist; Intel saw big business. By then, he already had his own product: Control Program/Monitor (CP/M), software that provided a computer's basic functions independently of its hardware.

The first tests ran on perhaps the most unusual system imaginable: a horoscope machine for carnivals. Its developer had accidentally typed "del ." (delete all) instead of "dir ." (list files), wiping everything. Kildall changed the command to "era" and added a safety prompt: "Are You Sure (Y/N)?"

Kildall wrote the first BIOS, which set up the operating system's environment at startup and could be adapted for any machine to make CP/M work on any hardware.

It was time to reap the rewards of his years of effort.

Gary Kidall And The Founding Of Digital Research Inc.

With his wife Dorothy, he founded Digital Research Inc. (DRI) to market CP/M. She used her maiden name, McEwen, to make the business seem smaller than it was. Dorothy handled communications and accounting, while Gary focused on programming.

It was a carefree time. The family lived well, then very well, on software revenue alone. One day, the bank even called to verify their income—with an 85% profit margin, the manager grew suspicious.

The profits and DRI's laid-back "hippie" atmosphere attracted top programmers. Kathy Strutynski worked on the Apple version and CP/M 2, adding early multitasking features.

Tom Rolander recalled spotting a model plane on Kildall's desk during his interview. Minutes later, they were at the airfield, flying the real thing. Rolander joined DRI two days later, earning the nickname "The Cannon"—point him at a coding problem, and he'd work nonstop until it was solved.

In the early 1980s, something happened that would forever change Gary Kildall, DRI, and the entire IT world.

IBM had decided to build its first personal computer. Though estimates suggested it would take nine months just to design the packaging, the project moved quickly.

Within a year, the hardware, built from off-the-shelf parts, was ready. All it needed was an operating system and a programming language. For the latter, IBM contacted a small firm called Microsoft, which had already adapted BASIC for several manufacturers. Its young CEO, Bill Gates, referred them to the market leader for an OS: DRI.

When IBM's suited delegation arrived at Digital Research's door, they handed Dorothy McEwen a non-disclosure agreement (NDA) stating that DRI couldn't disclose anything about the talks—while IBM could. Worse, any ideas discussed would become IBM's property.

Dorothy refused to sign, leaving the suits baffled. Neither she nor Gary (who arrived much later, by his account) knew IBM was desperate to keep the project secret because its off-the-shelf

design made it easy to copy. 

MS-DOS: Quick and Dirty

Kildall's calm didn't last. Soon, he saw what Microsoft was offering IBM: QDOS (Quick and Dirty Operating System). Written by 24-year-old Tim Paterson, it was CP/M-compatible and copied mainly from CP/M's documentation. Microsoft bought it for $50,000.

After IBM declared that negotiations with Kildall had failed, they returned to Gates. He gambled on three things:

1. The slapped-together OS would be ready in time.

2. Kildall wouldn't sue over the strikingly similar code.

3. IBM wouldn't cancel the PC project at the last minute.

All three bets paid off. Gates had little to lose—he was the most minor player in the deal.

The agreement with IBM was lopsided: Microsoft got a paltry sum for licensing QDOS, which was bare-bones but functional. IBM didn't foresee the clause letting Gates license QDOS to others—a move that would make Microsoft filthy rich.

As IBM PC clones (Compaq, Dell, HP) flooded the market, they needed the cheapest OS possible—MS-DOS. This laid the foundation for Microsoft's billions.

IBM worried about a lawsuit and offered Kildall a deal: PC buyers could choose their OS. What seemed like a guaranteed win (CP/M was the industry standard) backfired. Kildall agreed—and then saw the price tags: $240 for CP/M and $40 for QDOS.

Gary Kildall A Man With Plenty of Money But Little Happiness

It was too late to sue. A frantic call to IBM about lowering CP/M's price went unanswered. Kildall had been outmaneuvered by IBM and Microsoft. Did this ruin him? Hardly. CP/M remained the best system in the early 1980s, DRI thrived, and Kildall was a millionaire.

But bitterness festered. His marriage collapsed. He worked on groundbreaking projects like an early graphical interface and co-hosted the TV show "The Computer Chronicles"—sometimes, by his own admission, not entirely sober.

In 1985, he nearly sold DRI to Microsoft, but they offered $10 000 000 instead of his asking price of $26 million.

Ironically, DRI later released DR DOS, a superior MS-DOS clone that frustrated Gates. Users called it "Dr. DOS" for fixing Microsoft's bugs. Microsoft retaliated: Windows 3.1 "checked" for MS-DOS, locking out competitors.

Kildall never got the recognition he wanted. He began writing his autobiography to dispel the myth that he'd flown his private plane to the beach instead of meeting IBM in 1980.

As his health declined, he gave up flying—but not drinking. It likely contributed to his early death. Gary Kildall would have turned 83 in May 2025, but he died in 1994 at just 52, under unclear circumstances.