EMUL ATION

Mike Bedford shows you how to program the mechanical computing devices that pre-dated modern electronic computers by over a century.

OUR EXPERT Mike Bedford Like most of us, Mike tended to think of the likes of Alan Turing and John von Neumann as the pioneers of computing, so delving further into Charles Babbage’s creations was truly inspiring.

D iscussion about the first ever computer often results in heated debate fuelled, no doubt, by a degree of patriotism, but also by the vagaries of what’s meant by ‘the first computer’. More precise terms help us get closer to the facts. There’s widespread agreement, for example, that the first programmable, digital electronic computer was Colossus, as designed by British codebreakers in 1943 at the Government Code and Cypher School at Bletchley Park. But it differed from today’s computers in being programmed by flipping switches and plugging patch leads and, most importantly, because it was designed with particular jobs in mind, it wasn’t a general purpose machine.

Two years later, the University of Pennsylvania completed a massive machine containing thousands of thermionic valves – or electron tubes if you prefer – in a project funded by the US Army. It was called ENIAC – which stood for Electronic Numerical Integrator and Computer – and unlike Colossus, it was Turingcomplete, which meant it was a universal computer. It’s generally recognised as the first electronic programmable computer. Like Colossus, though, it didn’t hold its program in memory, so programming was a laborious process of patching leads and switches.

Next up is the machine that I’m most comfortable about calling the first ever computer, although admittedly that’s in no small part because it was built less than 50 miles from the place I call home. This was Manchester University’s modestly named SSEM (Small-Scale Experimental Machine), or colloquially the Manchester Baby. It ran its first program in 1948, it was a universal computer, and it held its program in memory, just like all today’s mainstream machines.

Bizarrely, though, computers don’t have to be fuelled by electronic circuits. Today, researchers are delving into biological computers, optical devices and machines powered by chemical reactions, to name but a few, but our subject here is a concept of computing that takes us back to the 19th century when advanced technology utilised cogs, gears, levers and steam engines. This is our earliest foray into reliving historical computers, it features the work of Charles Babbage, and this isn’t just a history lesson. If you want some hands-on experience, we’ll show you how to use a spreadsheet and an emulator to exercise a couple of computing devices, one of which was designed 200 years ago.