Sunday, July 19, 2009

Origins of the computer, the analog calculator

Absorbed by my next book, Consommation et technologie (Consumption and Technology), due out this fall (in French only for now), by my daily microblog on Twitter and by other publishing activities, amongst which an article titled « Le luxe de 1950 à 2020 : une nouvelle géoéconomie des acteurs » (Luxury from 1950 to 2020: a new geo-economics of actors) in the GÉOÉCONOMIE journal, I am forced to space out the columns of my blog, through lack of sufficient time. I beg you to forgive me.

Contrary to what I wrote at the end of my last column, this one will not be devoted to technological development of air weaponry in the United States. Pursuit of a series such as the one about war technologies, which began June 6, must be more sustained; I must interrupt it. I may take it up again one day.

Today I will give you a glimpse of my next book’s content, by talking about the origins of the computer. Two very different types exist: analog and digital. Let us begin with the analog computer.

It’s a mechanical data management device «expressed through physical measurements (for example, intensities, tensions or hydraulic pressures) », whose gear work is driven by electric motors or hydraulic pistons. The Chinese abacus and the slide rule formerly used by engineers are examples of manually operated analog «computers». Vannevar Bush, professor at the Massachusetts Institute of Technology, was the first to develop the first functional analog computer in 1931; he called it «continuous integraph», later renamed «differential analyzer».

The «differential analyzer» is a huge machine that uses the ten digits of the decimal system rather than the binary system of today’s computers; it’s one of Bush’s student, Claude Shannon, who suggests in his master dissertation the practical application of Boolean algebra and binary arithmetic to electrical circuits, work on the «differential analyzer» having led him to look for ways to improve the device, by replacing the wheels with electric circuits amongst others.

During World War II, the Norden bombsight which equipped USAF bombers uses an analog computer to calculate the point of impact of bombs. Until the 1960s, perhaps even the 1970s, banks have used electromechanical calculators using Bush’s analog computer concept. Digital machines subsequently relegated these first computers to history’s oubliettes.

Bush is nonetheless visionary. In «As We May Think» an article published in 1945 in «The Atlantic», he foresees the dominance of digital programmable computers over their analog cousins: «The advanced arithmetical machines of the future will be electrical in nature, and they will perform at 100 times present speeds, or more [...] they will select their own data and manipulate it in accordance with the instructions thus inserted. » Bush recognizes the advantages of digital calculators and programming languages developed during the Second World War.

In my next column, I will continue with digital computers.

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