At a Saturday auction in Cologne, Germany, a treasured trove of some exclusive one-offs and oddities from the tech arena, as well as a few technology "firsts," will be put up for sale.

Among the unique tech items going under the hammer at the forthcoming auction in Germany are: an experimental mechanical calculator from the 17th century; a 108-year-old telephone; and an extraordinarily rare, headline-grabbing Apple-1 computer - a model which was launched in 1976.

According to the German auctioneer Uwe Breker, the Apple-1 computer which will be auctioned on Saturday was originally purchased by former baseball player Fred Hatfield, who played as an infielder in major leagues during the period from 1950 to 1958. Hatfield - whose nickname was `Scrap Iron' - played for five teams, including the Boston Red Sox and the Cincinnati Redlegs. He died in 1998, at the age of 73 years.

The documents which come along with the soon-to-be-auctioned Apple-1 computer include a letter to Hatfield, signed by Apple's iconic CEO, late Steve Jobs. In the letter, Jobs offered Hatfield a new Apple II as well as check for $400 for his Apple-1. However, the offer was turned down by Hatfield.

As per Breker, the Apple-1 computer is being sold by a young American who works for a software firm. The reserve price - minimum sale price - for the computer is $116,000; and, going by Breker's somewhat conservative estimates, the device will likely sell in the range of between $260,000 and $400,000.