COMPUTING PRE- HISTORY
Defining the earliest “computer” is tricky, but they’ve certainly been around for longer than you might think
ONE OF THE EARLIEST MACHINES to be accepted as an analog computer is the Antikythera Mechanism. Dated to around 100 BC, it was used in astronomy to determine the positions of celestial bodies decades in advance. Only fragments of it remain, but detailed imaging suggests it could even model the irregular orbit of the moon. You can find a simulation of the Antikythera Mechanism at www.etl.uom.gr/mr/index.php?mypage=antikythera_sim. It only has a Windows executable, but it runs under Wine.
In the 13th century, we find Turkish inventor Ismail al-Jazari and his automata, laid out in his Book of Knowledge of Ingenious Mechanical Devices. Al-Jazari made complex mechanical musicians that ran via clockwork, and even had a programmable drum machine, coded by altering the movement of cams. However, documentaries usually start just before the Victorian era. In those days the word “computer” would have evoked an image of a guy with a pencil behind his ear doing math. But these squishy creatures were unreliable at best, and a machine with unerring accuracy was needed for a genuine technical revolution.
SPLIT THE DIFFERENCE Enter Charles Babbage (1791-1871) and his Difference Engine. This was a mechanical number-cruncher, powered by a hand crank, with digits shown on rotating dials. It could not only perform arithmetic, but could also be programmed to follow numeric sequences, and even extract the root of a quadratic equation.
Babbage also designed the Analytical Engine, though it was never built. This would have been so far ahead of its time that it’s almost scary, with features much like a mainframe computer of the mid 20th century: punch-card programming, 16.2K of decimal storage, a grid layout with its own internal procedures, like a CPU dubbed “The Mill,” and something akin to assembly language.
Unfortunately, withdrawn funding meant the Difference Engine was never completed (Babbage only made a strippeddown prototype), and there was no interest in producing the even more elaborate Analytical Engine. Nevertheless, enough design existed for Babbage’s friend Ada Lovelace to write an algorithm for it, thus Lovelace is generally credited as having written the first computer program.
Victorian Britain may not have been interested in completing the Difference Engine, but thankfully modern Britain is. If you want to try out the Difference Engine, there are some simulations online, and a Python script on GitHub if you want to look for them. If you want to see it in the metal, as it were, the Science Museum in London has an operational section on display. Meanwhile, the Analytical Engine is currently being built by the Plan28 organization—see http://plan28.org for more info.