From time to time you hear about Apple’s first computer, the Apple 1, selling to collectors at auction for big bucks. But did you know some of those surviving antiques carry an enduring mystery? For decades, no one could figure out who wrote the serial numbers on their circuit boards. Until now.
The mystery of the handwritten Apple 1 serial numbers
Both Apple co-founders Steve Jobs and Steve Wozniak denied they wrote the serial numbers. The friend of Jobs who assembled and tested some of the boards, Daniel Kottke, said the same. And so did Paul Terrell, who bought 50 of the computers for the Byte Shop in Mountain View, California.
So Achim Baqué, who maintains the Apple-1 Registry — a list of all Apple 1 computers — set about cracking the case. And it turned out to be a pretty tricky mystery to solve.
Although Jobs said he did not write the serial numbers, they appear to match his handwriting. Given the rarity of Jobs autographs, they’re super-valuable to collectors. So Apple 1 computers that he wrote on could see an increase in value. That added urgency to the task of accurately figuring out who wrote those numbers.

Photo: Achim Baqué, Apple-1 Registry
Top handwriting expert enlisted
Baqué requested that one of the leading handwriting authentication services compare samples of Jobs’ writing to the serial numbers on two of the Apple 1 boards.
California-based authentication company PSA took the job, but indicated photos would not cut it. The company said it needed to physically examine the writing samples and the boards. Such tests cover several characteristics of a person’s writing, including slant, flow, pen pressure, letter size and more.
A contribution of letters and postcards Jobs wrote came from his friend Kottke. Some of those documents included handwritten numbers, which helped the process.
Based in Germany, Baqué personally delivered two of the boards, along with the handwriting samples, to PSA in California.
After three months of analysis, including the careful study of many photos, the company officially authenticated the handwriting on the boards. Steve Jobs wrote the Apple 1 serial numbers. Apparently he just didn’t recall doing it.
Mystery solved! You can read much more about it at the Apple-1 Registry.