DALLAS (AP) — Jerry Merryman, one of the inventors of the hand-held electronic calculator who is described by those who knew him as not only brilliant but also kind with a good sense of humor, has died. He was 86.

Merryman died Feb. 27 at a Dallas hospital from complications of heart and kidney failure, said his stepdaughter, Kim Ikovic. She said he'd been hospitalized since late December after experiencing complications during surgery to install a pacemaker.

He's one of the three men credited with inventing the hand-held calculator while working at Dallas-based Texas Instruments. The team was led by Jack Kilby, who made way for today's computers with the invention of the integrated circuit and won the Nobel Prize. The prototype built by the team, which also included James Van Tassel, is at the Smithsonian Institution.

"I have a Ph.D. in material science and I've known hundreds of scientists, professors, Nobel prize-winners and so on. Jerry Merryman was the most brilliant man that I've ever met. Period. Absolutely, outstandingly brilliant," said Vernon Porter, a former TI colleague and friend. "He had an incredible memory and he had an ability to pull up formulas, information, on almost any subject."

Another former TI colleague and friend, Ed Millis, said, "Jerry did the circuit design on this thing in three days, and if he was ever around, he'd lean over and say, 'and nights.'"

Merryman told NPR's "All Things Considered" in 2013, "It was late 1965 and Jack Kilby, my boss, presented the idea of a calculator. He called some people in his office. He says, we'd like to have some sort of computing device, perhaps to replace the slide rule. It would be nice if it were as small as this little book that I have in my hand."

Merryman added, "Silly me, I thought we were just making a calculator, but we were creating an electronic revolution."

The Smithsonian says that the three had made enough progress by September 1967 to apply for a patent, which was subsequently revised before the final application in June 1974.

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Merryman, who was born on June 17, 1932, grew up in Hearne in Central Texas. By the age of 11 or so he'd become the radio repairman for the town.

"He'd scrape together a few cents to go to the movies in the afternoons and evenings and the police would come get him out ... because their radios would break and he had to fix them," said Merryman's wife, Phyllis Merryman.

He went to Texas A&M University in College Station but didn't finish. His jobs after that included working at the university's department of oceanography and meteorology and before long he was on an oil platform in the Gulf of Mexico measuring the force of hurricane winds. He started at Texas Instruments in 1963, at the age of 30.

His friends and family say he was always creating something. His daughter Melissa Merryman recalls him making his own tuning fork for their piano. She said she asked him how he made it out of that "hunk of metal" and he told her: "It was easy, I just took away all the parts that were not an F sharp."

Friend and former TI colleague Gaynel Lockhart remembers a telescope in concrete at Jerry Merryman's home with a motor attached that would allow it to follow a planet throughout the night.

Despite his accomplishments, he was humble. "He wouldn't ever boast or brag about himself, not ever," said Melissa Merryman, who became stepsisters with her friend Kim Ikovic when they set up their parents, who got married in 1993.

Jerry Merryman retired from TI in January 1994, the company said.

"He always said that he didn't care anything about being famous, if his friends thought he did a good job, he was happy," Phyllis Merryman said.