Sometimes it is called “Grandpa Mark.” In fact, it is the ancestor of today's computers, which are widely used at home now: on August 7, 1944, the first American programmable computer Mark I was launched in Harvard, USA.

The glass and stainless-steel case containing about 765,000 parts, such as electromechanical relays and switches, was 17 meters long, more than two and a half meters high, and weighed four and a half tons. The connecting wires alone in the computer would be enough for seven skeins across the Moscow Ring Road, with their total length of 800 kilometers. A 15-meter shaft on a five-horsepower electric motor synchronized the main computing modules.

The computer operated with 72 numbers, which consisted of 23 decimal places. 3 addition or subtraction operations per second, about 6 seconds for multiplication, even longer for division – 15.3 seconds. Calculating logarithms and trigonometric functions took more than a minute. Basically, it was an improved calculator: the first computer could replace the work of 20 operators with manual calculators. The computer, however, became known exactly for the fact that it did not require any human interaction in the working process.

Computational programs were uploaded to the computer on a perforated tape. Mark I sequentially read and executed the instructions from the paper. The computer did not know how to make conditional transitions, so each program looked like a very long tape roll. The cycles were organized by looping the beginning and the end of the tape to be read. The principle of separating data and instructions became known as the Harvard architecture.

The computer development was financed by the U.S. Navy. IBM served as a contractor: a group of five development engineers worked under the guidance of U.S. Navy Captain 2nd Rank Howard Aiken, and the computer was based on the work of British scientist Charles Babbage, who invented the first analytical computing machine in the mid-19th century. It cost $500,000 to build the computer.


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Based on materials from, Википедия