His mother Emma was of half Swedish descent, as Kildall's grandmother was born in Långbäck, Sweden, in Skellefteå Municipality, but emigrated to Canada at 23 years of age.

[16] He created CP/M the same year to enable the 8080 to control a floppy drive, combining for the first time all the essential components of a computer at the microcomputer scale.

In response, Kildall pioneered the concept of a BIOS, a set of simple programs stored in the computer hardware (ROM or EPROM chip) that enabled CP/M to run on different systems without modification.

After hardware manufacturers talked about creating a rival operating system, Kildall started a rush project to develop CP/M 2.

On the advice of DRI attorney Gerry Davis, Dorothy refused to sign the agreement without Gary's approval.

[21] Sams related the story to Gates, who had already agreed to provide a BASIC interpreter and several other programs for the PC.

[26] Kildall accepted, believing that IBM's new system (like its previous personal computers) would not be a significant commercial success.

[28] In 1985 Digital Research developed FlexOS, a modular real-time multiuser multitasking operating system (RTOS).

[29][30] After seeing a demonstration of the Apple Lisa, Kildall oversaw the creation of DRI's own graphical user interface, called GEM, which was introduced on February 28, 1985.

[32] Kildall co-hosted a public television program produced by PBS called Computer Chronicles.

In 1984 Gary started another company, Activenture, which adapted optical disc technology for computer use,[33] using as reference the Red Book developed by Sony and Phillips in 1980.

[35] Kildall's final business venture, known as Prometheus Light and Sound (PLS) and based in Austin, Texas, developed a modular PBX communication system[12] that integrated land-line telephones with mobile phones (called "Intelliphone") to reduce the then-high online costs and to remotely connect with home appliances.

According to Brian Halla, Intel's technical liaison to Digital Research in the 1970s, Gary Kildall showed him a VAX 11/780 running in his house generating a Coke bottle spinning.

He also took offense at the decision to give the keynote speech to Bill Gates, a Harvard dropout who had donated to UW, but had never attended.

[7] IBM veterans from the PC project disputed the book's description of events, and Microsoft described it as "one-sided and inaccurate.

A legend grew around the fateful IBM-DRI meeting, encouraged by Gates and various journalists,[24][41] suggesting that Kildall had irresponsibly taken the day off for a recreational flight.

[7] In later years, Kildall privately expressed bitter feelings about being overshadowed by Microsoft,[12] and began suffering from alcoholism.

[25][42] Selling DRI to Novell had made Kildall a wealthy man, and he moved to the West Lake Hills suburb of Austin.

His Austin house was a lakeside property, with stalls for several sports cars, and a video studio in the basement.

[23] Harold Evans, in They Made America, states that Kildall "stumbled and hit his head" inside the premises, and "was found on the floor.

[40][4] Evans states that Kildall's head injury triggered a cerebral hemorrhage, causing a blood clot to form inside the skull.

[7] A CP/M Usenet FAQ states that Kildall was concussed due to his injury, and died of a heart attack; the connection between the two is unclear.

According to the coroner's report, Kildall's fatal injury may have taken place "as a result of foul play," and the case was referred to the Monterey Police Department.

[7] Following the announcement of Kildall's death, Bill Gates commented that he was "one of the original pioneers of the PC revolution" and "a very creative computer scientist who did excellent work.

"[46] In March 1995, Kildall was posthumously honored by the Software Publishers Association (SPA) for his contributions to the microcomputer industry:[47][48][12] In April 2014, the city of Pacific Grove installed a commemorative plaque outside Kildall's former residence, which also served as the early headquarters of Digital Research.