A prototype Apple 1, a holy-grail item in electronics memorabilia, has been sold for $815,000 (£618,000).
Apple co-founders Steve Jobs and Steve Wozniak built just 200 of the computers in 1976.
The model auctioned this week contains tell-tale signs that it is a prototype, probably made prior to its manufacturing run.
One computer historian says it is “one of the first, if not the first ever” Apple computer.
This “celebration edition” Apple 1 was expected to make $1m, but auctioneer Charitybuzz told the BBC that the final bid was $815,000.
That means it is not the highest-grossing Apple 1 computer – that distinction belongs to a rare working version that sold for $905,000 at a Bonhams auction in New York in October 2014.
A spokeswoman for Charitybuzz said that “about 80 bidders” had been watching the item. She denied reports that there had been a last-minute $1.2m bid, apparently made too late to be accepted.
Ten percent of the proceeds will go to the Leukemia and Lymphoma Society, based in New York, Charitybuzz said.
The winning bidders, Glenn and Shannon Dellimore, said they want to take the computer into schools and universities to help inspire young people.
Mr Dellimore told the BBC: “It is incredible to think that this was most likely the very first Apple 1, the unicorn or holy grail of computers, the original very first prototype.”
No more than 70 Apple 1 computers are believed to still be in existence. The machine – initially named “Apple Computer 1” – first went on sale in July 1976, and was discontinued in October of the following year when the company turned its attention to building the Apple 2.
The “celebration edition” is different from the other Apple 1s because it was manually soldered on to a blank PC board, meaning it was not part of the only two production runs of the device.
Mr Wozniak was quoted by Charitybuzz as saying: “Only a few Apple 1s, on blank (not green) PC boards, may have been manually soldered, although I’m not sure of it.
“We arranged the wave soldering with the company that made the PC boards. But we may not have wanted to wave solder a run (of maybe 10 or more board) until we manually soldered one or two to debug them.”
Apple historian Corey Cohen, who assessed the machine, said in a promotional video that the celebration edition is “one of the first, if not the first, Apple computers because this appears to be one of the sample boards”.
According to a timestamp on the PC board, it was made in the summer of 1976.
Jobs, Wozniak, and Ronald Wayne founded Apple on 1 April 1976 in California in the garage of Paul and Clara Jobs.
The trio’s first major project was the Apple 1 computer, which was first unveiled at the Homebrew Computer Club – a hobbyist group in Silicon Valley.
To help finance the machine’s production, Jobs sold his VW Microbus, while Wozniak sold his HP-65 calculator for $500.
The Apple 1 went on sale in July 1976 at a price of $666.66.
About 175 of the 200 units were sold, while the remaining units were destroyed.
Two weeks after Apple’s formation, Mr Wayne sold his 10% stake for $800.
The company’s annual revenue last year was $234bn.