An Apple-1 circuit board that was hand-soldered by Apple co-founder Steve "Woz" Wozniak and reportedly used to secure Apple's first big order is up for auction now. 

The unit is an "Apple Computer A" prototype - a circuit board rather than a fully assembled Apple-1 PC - but with suitable provenance and legend that should see it sold for at least$500,000 at Boston-based RR Auction. 

Apple

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This prototype is the one that Steve Jobs in 1976 demoed to Paul Terrell, the owner of the Byte Shop in Mountain View, who convinced Jobs to sell his product as an assembled computer rather than as a circuitboard. 

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Jobs initially wanted to sell a circuitboard for$40, much like today's$35 Raspberry Pi, as a DIY project. Instead, Jobs heeded Terrell's advice, pre-assembled the Apple-I, and sold it for$666.66. The circuitboard Jobs and Wozniak presented to the Homebrew Computer Club in 1976 used the BASIC programming language for interaction. Users needed to bring their own storage, power supply and keyboard. 

Terrell later placed an order for 50 Apple-1 with Wozniak, changing the course of Apple's trajectory - from a small operation in the 'Apple Garage' to the$2.5 trillion tech behemoth it is today, which designs in California but assembles everything in China. 

Bids opened on July 20 and the latest bid, placed today, was$407,029. Bidding closes on August 18.

"The board has been matched to Polaroid photographs taken by Paul Terrell in 1976 showing the prototype in use, first published by Time Magazine in 2012 and also covered by Achim Baqu