After earning a bachelor’s degree in electrical engineering, followed by master’s and Ph.D. degrees, Niklaus Wirth began his career in teaching — first at Stanford University, then at his undergraduate alma mater, the Swiss Federal Institute of Technology (ETH), where he remained from 1968 until his retirement in 1999.

When tasked with starting the school’s computer science department, Wirth found the programming languages available at the time too complex — so he created his own. He released Pascal and its source code to the community in 1970 and introduced it to the classroom in 1971.

The result was a success, recalled Wirth: “It allowed the teacher to concentrate more heavily on structures and concepts than features and peculiarities — that is, on principles rather than techniques.” Pascal became an introduction to programming for generations of students — though it was not merely an academic exercise.

“I do not believe in using tools and formalisms in teaching that are inadequate for any practical task,” said Wirth. “[Pascal] represented a sensible compromise between what was desirable and what was effective.”

During his time at ETH, Wirth took two sabbaticals to work at Xerox PARC. There, he encountered the Alto computer, his first time using a personal computer that he didn’t need to timeshare with others. The experience inspired him to return to Switzerland and build his own personal computers and their accompanying software. Languages he developed for these computers included Modula-2 (1979) and Oberon (1988). Ultimately, Wirth was his own best student: “One learns best when inventing,” he said.

Wirth was honored in 1984 with ACM’s Turing Award and in 2004 as a Computer History Museum Fellow. He died at 89.

Some inventors have ideas ahead of their time; it takes decades for technology and society to catch up. That’s why it wasn’t until 2000 that Herbert Kroemer received the Nobel Prize in Physics for his work in heterostructures dating back to the 1960s.

Kroemer earned his Ph.D. at the age of 23 before joining a semiconductor research group in the German postal service in 1952. Charged with improving the rate and reliability of transistors (still fairly new at the time, having been invented in 1947), Kroemer proposed improvements that required technology that did not yet exist. Kroemer’s proposals were eventually implemented in what became known as heterostructure transistors.

In 1963, while working at one of Silicon Valley’s first high-tech companies, Varian Associates, Kroemer recommended using heterostructures for lasers as well, enabling them to operate continuously at room temperature. He received the patent for his idea in 1967, which led to the creation of laser diodes — a technology with applications both small (disc players, barcode scanners) and large (satellite communications, fiber optics).

In 1976, after eight years on the faculty at the University of Colorado, Kroemer moved to University of California, Santa Barbara, where he remained until his retirement in 2012.

Kroemer once said, “Small steps didn’t really interest me. I was interested in big steps.” Those big steps earned him not only the 2000 Nobel Prize, but also the 2001 Grand Cross of the Order of Merit of the Federal Republic of Germany and the 2002 IEEE Medal of Honor. He was 95 when he passed.

Entering college on a French horn music scholarship, Robert Dennard earned his bachelor’s, master’s, and Ph.D. degrees in electrical engineering. He then joined IBM as a researcher in 1954.

At that time, storing a single bit of information in memory required six transistors — a relatively expensive and limiting technique. In 1966, Dennard delivered dramatic improvements in speed and capacity when he invented the one-transistor memory cell. This design became the basis for dynamic RAM, or DRAM, which is used in practically all computing devices to this day.

Dennard also worked on metal-oxide-semiconductor field-effect transistors (MOSFETs). In a 1974 paper he co-authored, Dennard described how transistors could become smaller (in accordance with Moore’s Law) while retaining the same energy consumption — a principle that became known as Dennard scaling.

Dennard’s innovations earned him the United States’ National Medal of Technology and Innovation in 1988 and the Kyoto Prize in Advanced Technology in 2013. Yet Dennard remained humble, saying, “I’m a very ordinary person, with a very ordinary background and upbringing… It’s not enough to just think creatively. Once you’ve posed the question, you’ve got to answer the question.”

Dennard stayed at IBM until his retirement in 2014. He died at 91 from a bacterial infection.

While working at IBM on the Advanced Computing Systems project in the 1960s, Lynn Conway developed dynamic instruction scheduling (DIS), a computing architecture technique that enabled computers to perform multiple operations simultaneously, paving the way for the first superscalar computer.

Conway’s reward: she was fired from IBM and all record of her work expunged — all because she’d come out to her employer as being transgender. With her career erased, Conway underwent gender-affirming surgery and began a new career under a new name.

Despite the professional setback, Conway continued building a legacy of profound innovations. In 1973, while working at Xerox PARC with Carver Mead and Bert Sutherland, she co-developed very large-scale integration (VLSI), enabling microchips to hold millions of circuits — kicking off a revolution in computer architecture and design. She returned to MIT, a school she’d previously dropped out of in the 1950s after a physician threatened her with institutionalization, to teach the university’s first VLSI design course.

Conway then worked at DARPA before joining the faculty of the University of Michigan, where she remained for 13 years until her retirement in 1998. She did not come out about her work at IBM until 2000, after which she became an outspoken advocate for transgender rights. Conway was heartened by the changing landscape compared to when she grew up, saying: “Parents who have transgender children are discovering that if they… let that person blossom into who they need to be, they often see just remarkable flourishing of a life force.”

In 2020, fifty-two years after Conway was fired, IBM issued a formal apology.

She passed away at the age of 86 from a heart condition.

In 1979, while earning his master’s degree in computer science at Brigham Young University, Bruce Bastian partnered with his professor, Alan Ashton, to co-found Satellite Software International. Their flagship product was word processing software that they had co-developed for the city of Orem, Utah. That program later became the new name of their company: WordPerfect Corporation.

The WordPerfect software debuted several innovations, including function-key shortcuts, numbering of lines in legal documents, and a scripting capability. It went toe-to-toe with Microsoft Word, trouncing it in the MS-DOS era but proving slow to catch up in Windows, where Microsoft bundled Word in its Office suite. But over the years, versions of WordPerfect also proliferated for Atari, Amiga, Unix, Linux, Macintosh, and iOS devices.

WordPerfect was acquired by Novell in 1994 and by Corel, now Alludo, in 1996. Only the Windows version is still supported, having been most recently updated in 2021; it remains popular, especially among lawyers.

Bastian left the Mormon church in the 1980s when he came out as gay. He became a staunch advocate for LGBTQIA+ rights, sitting on the board of the nonprofit Human Rights Campaign and donating $1 million to defeat California’s Proposition 8 to outlaw same-sex marriage in 2008. His own nonprofit, the B.W. Bastian Foundation, continues to support organizations that further human rights and the LGBTQIA+ community.

“I’m doing this for the kid in Idaho, growing up on a farm. I don’t want him to go through the s— I went through,” Bastian told the Salt Lake Tribune.

Bastian died at 76 from complications associated with pulmonary fibrosis.

When Larry Page and Sergey Brin founded Google in 1998, they needed office space. Management consultant Susan Wojcicki provided her garage — and, over the years, so much more.

Hired as Google employee #16, Wojcicki went on to play several defining roles in the company: she was Google’s first marketing manager in 1999; she product-managed the launch of Google Image Search in 2001; she was AdSense’s first product manager in 2003; and, while heading the nascent Google Video division, she initiated and managed Google’s acquisition of competitor YouTube in 2006.

In 2014, Wojcicki was appointed CEO of YouTube. Over the next nine years, she oversaw the service’s expansion into multiple countries, languages, and brands, including YouTube Premium, TV, Shorts, Music, and Gaming. The platform’s annual advertising revenue now exceeds $50 billion.

Throughout her career, Wojcicki’s work embodied the early days of Google, which she defined as “incredible product and technology innovation, huge opportunities, and a healthy disregard for the impossible.” She stepped down as YouTube CEO in February 2023, remaining in an advisory role at parent company Alphabet. She passed away 18 months later at age 56 from lung cancer.

Ward Christensen spent his entire 44-year career as a systems engineer at IBM — but it was his hobbies that earned him a place in history.

In 1977, when Christensen needed to convert a CP/M floppy disk to an audio cassette, he developed a transfer protocol consisting of 128-byte blocks, the sector size used by CP/M floppies. The protocol proved so versatile and reliable for a variety of platforms that it evolved into XMODEM, which became a standard for transferring data files across dial-up modem connections, especially at slower speeds such as 300 baud.

Christensen’s work on XMODEM earned him a sponsorship from the White Sands Missile Range to dial into the ARPANET. But he was frustrated by the organization’s design-by-committee approach, where ideas languished. When Chicago’s Great Blizzard of 1978 left Christensen and his fellow computing enthusiasts stranded in their homes, Christensen called his friend Randy Suess to develop a way for their local hobby computer club to meet virtually. The two collaborated, with Suess providing the hardware and Christensen the software. Within two weeks, the Computerized Bulletin Board System (CBBS) was up and running.

CBBS became the first of tens of thousands of dial-up BBSes that proliferated over the next twenty years. BBSes formed some of the first online communities and became important shareware distribution nodes for early game companies. The groundbreaking innovation earned Christensen multiple awards and recognition, including a 1993 Pioneer Award from the Electronic Frontier Foundation.

Christensen retired from IBM in 2012, after which he remained active in Build-a-Blinkie, a nonprofit that teaches basic computer hardware skills. “I [can] think of no finer testimony to the soul behind this pioneer than the fact that up to the end of his life, he was teaching very young children how to solder together electronics to get them interested in science and engineering,” said Jason Scott, creator of BBS: The Documentary.

Christensen died at home from a heart attack at the age of 78.

In 1959, the University of Illinois at Urbana-Champaign’s Control Systems Laboratory set out to develop a computerized learning system. They hired Don Bitzer, who’d just earned his bachelor’s, master’s, and Ph.D. degrees in electrical engineering from the school.

Bitzer accomplished what a committee could not, and the result was Program Logic for Automatic Teaching Operations, or PLATO. The system was jam-packed with content, including tens of thousands of hours of course materials, Star Trek-inspired games, and a message board that constituted an early online community. The hardware, initially based on the ILLIAC I computer, was equally groundbreaking: PLATO was one of the first computers to combine a touchscreen with graphics, and it was an early example of timesharing — an innovation University of Illinois might’ve earned a patent for, had the paperwork not been misfiled.

In 1964, the PLATO IV model debuted another innovation: the flat-panel plasma display. This alternative to traditional cathode-ray tube (CRT) displays, invented by Bitzer, H. Gene Slottow, and Robert Willson, rippled far beyond academic computers: decades later, it became the basis for flatscreen, high-definition televisions, used in computers and entertainment worldwide. For this work, Bitzer received a 2002 Technology & Engineering Emmy Award.

In 1989, Bitzer joined the faculty of NC State University in Raleigh, North Carolina, where he remained until retirement. He was inducted into the National Inventors Hall of Fame in 2013, the National Academy of Inventors in 2018, and as a fellow of the Computer History Museum in 2022.

“He was a rare systems-level individual who could easily move between hardware and software, and wrangled both sets of people, all while evangelizing the entire PLATO platform to any individual or organization who would listen,” said Thom Cherryhomes, creator of IRATA.ONLINE, a modern online community based on the PLATO system.

Bitzer was 90 when he died at home.