­On Dec. 11, as part of what is being calling the Exceptional Sale, Christie’s in New York will auction off the “Ricketts” Apple-1 personal computer, a surviving example of the first model Apple sold commercially, in 1976. This particular computer — a green circuit board mounted under glass — can trace its history clear back to Steve Jobs’s parents’ garage (its original owner and namesake, Charles Ricketts, bought the computer there, as evidenced by a canceled check for $600 that is part of the sale). It is estimated to fetch $400,000 to $600,000 and will likely go higher, as did one that sold for $671,400 last year at Breker auction house in Germany.

To assess the condition of the “Ricketts” Apple-1 and bring it to full operation, Christie’s called in Corey Cohen, a 43-year-old manager at a software company and vintage computer enthusiast from New Jersey who has become to early Apple circuitry what Renaissance art historians are to Caravaggios. Mr. Cohen spoke last week about his newfound role and the beauty of the Apple-1 design. (This interview has been edited and condensed.)

Q. How did you become the go-to guy to assess Apple-1s for auction houses?

A. There was a sale a few years ago when a board came up at Sotheby’s. They were going to do the press event and somehow the machine wasn’t working. The owner had come to New York and we’d conversed. I got a panicked call from him. I repaired what was wrong with that machine. Word spread. I started collecting original Apple-1 replacement parts to restore them back to original condition. I got to be known as the parts guy. I’m big into the vintage computer scene.

I didn’t realize collecting vintage computers was a scene.

­It very much mimics the classic car community. You see the different factions: Should something look cosmetically correct? What’s a restoration versus a rebuild? It’s less messy than rebuilding an engine of a car. But like car collecting, you’re starting to see some of these computers be escalated to works of art.