One of the most rare and valuable Apple 1 computers, which is still in  working condition after being hand-built 37 years ago, will go on sale during an auction Saturday in Cologne, Germany.

What makes the Apple 1 computer so valuable? Well, firstly the Apple 1 computer marks the start of Apple's creation story. It was hand-built by Stephen G. Wozniak, co-founder of Apple Inc. and its rarity makes it more valuable as there are only six of these original Apple computers, which still work.

Wozniak had built only 200 of these Apple 1 computers in 1976 when he first started the Apple Computer Company with Steve Jobs, who passed away in 2011 suffering from cancer. The computer was originally owned by Fred Hatfield, a former baseball player also known as "Scrap Iron." He played from 1950 to 1958 in major leagues for teams like Boston Red Sox and the Cincinnati Redlegs. These computers were built in the Jobs family garage in Los Altos, California, according to NY Times.

Apple's new computers and iMacs are much advanced in terms of configuration and 300 times cheaper than the valuable Apple 1. The first of Apple computers had 4 Kilobytes of memory, which in comparison to today's basic iMac is millions of times lesser. These old computers were designed to write simple programs and run ancient computer games.

The German auction house sold an Apple 1 computer November, last year, for $640,000, which beats the previous record set by selling another Apple 1 computer for $374,500 at Sotheby's in New York, June last year. The German auction house will display the working Apple 1 computer to potential bidders on Friday before it goes on sale the next day.

Auctioneer, Uwe Breker expects the Apple 1 computer to fetch $260,000 to $400,000 and the minimum sale price is set at $116,000, according to NY Times. The machines were originally priced at $666.66 when they were released in July 1976.

Besides a rare Apple 1 computer, the German auction house will also display a series of other antiques, including the 1983 Apple Lisa, one of the world's first mouse-controlled computers, 1895 Ford typewriter, 1905 desk telephone and world's first mechanical calculator designed by French philosopher, physicist and mathematician, Blaise Pascal.

Watch the video below released by AUCTION TEAM BREKER which shows the functioning of Apple 1: