A rare, working Apple I computer known as the "Hatfield" unit is going back under the hammer this autumn, with auction house Bonhams estimating it could fetch between $500,000 and $800,000. The machine last sold for $671,400 in 2013, and its return to auction highlights the enduring collector demand for early Apple hardware, even though the Apple I never achieved mainstream commercial success in its own right. Fewer than 75 of these computers are thought to survive today, making working examples like this one especially prized by collectors.

The Apple I, of which only around 200 were made, retailed for $666.66 in the mid-1970s and required buyers to supply their own power supply, keyboard and monitor, with just 4KB of RAM. This particular unit, No. 48 on the Apple I Registry, is named after original owner Fred Hatfield and features a motherboard signed by Apple co-founder Steve Wozniak. It also comes with a 1978 letter signed by Steve Jobs, offering Hatfield a trade-in for an Apple II after he complained about a lack of software; Hatfield declined and later sold the machine for $40,000. Bonhams will tour the computer through Los Angeles, Boston and San Francisco before the sale concludes in New York on 14 October.