Babbage Difference Engine No.2
Copyright 1991, Peter D Rieden

Delving back into my archive yielded the following piece which I believe I originally painted onto the stretched vellum in 1991. The covering note at the beginning dates from 1996 when I last retrieved this particular bit of prose. It helps if you can remember the Sinclair QL...


"I wrote the following some years ago when the Science Museum announced their intention to build a Babbage Difference Engine to determine once and for all whether Babbage's machines would work. The story bears more than a passing resemblance to some of Clive Sinclair's projects - whilst reading think back to the Sinclair QL... It was circulated to a select ALL-IN-1 audience and provoked a lively correspondence at the time."

At last it's here: the Difference Engine No.2, an all British product, designed, built and tested at Babbage's new workshops at the Science Museum, aimed at the small business market and, according to Babbage, "realistically priced at 290,000".

From the engine's first announcement in 1847 to its completion, it has had a long and troubled life. Critics have said of its 140 year development that perhaps Babbage was somewhat premature in his announcement because he didn't have the technology to build the engine. Babbage answered by attributing the delays to `temporary production difficulties with my suppliers - of course my death didn't help matters much'. He went on: `I never intended the engine to be produced in 1847. I just wanted to get the credit before anyone else thought of the idea'.

Babbage was never one to hide his light under a bushel. The 15 year production delay on his difference engine No.1 was a good indication of the problems to come. Babbage denied the delay caused any difficulties, but sources close to him say it caused the collapse of his less than bulging order book, and that the South London entrepreneur had to sink a considerable amount of his own money into the engine after repeatedly asking the government to bail him out.

On first viewing, the engine is awesome: 6'high, 10'long and 2'wide. It is built from black painted gunmetal and brass, which gives it a rather distinguished look; however, weighing in at over 3 tonnes, you would have a few problems installing it on a desktop. Babbage assures us a portable version will be available when he can find a "horseless carriage" powerful enough to pull it.

The engine has 2 unique features: the manual power drive, and the distinctive flicker free, low radiation, low power display. The manual drive requires the user to turn a large wooden handle four times per instruction; fine for simple addition but somewhat tedious for finite element analysis. There are plans to replace the handle with a Rottweiler powered treadmill in a future "Executive Model".

The single line 30 character display has a 1 Hz refresh rate with photographic resolution and zero radiated emissions - an achievement Babbage claims to be a world first.

The engine has a zero wait state processor construction with some embedded parallelism; the clock speed is dependent on the manual drive but averages at around 1Hz. The engine has a 30 bit (all internal bits are decimal rather than binary) internal word and a 30 bit data/address bus. There are 248 bits of non-volatile BOB (Brass On Brass) memory split into 217 bits of programmable RAM and 31 bits for the bit mapped display. The engine benchmarks at around .0000001 MIPS, depending on how fast you turn the handle. However, with this type of performance it's not going to compete with too many of the current i486 machines[sic].

The engine has some major hardware limitations, with no provision for networking and, even more alarmingly, no serial or parallel ports. The engine is not IBM compatible; when asked about this Babbage replied "That never stopped the Apple Mac".

As yet little software has been written for the machine. The Director of Babbage's Application Support Division stated that most of her resources were dedicated to the engine's successor. Babbage said that Ashton-Tate, Borland and Lotus were porting applications; however, when approached all the companies denied any links with Babbage. A BSI source did say that a BabOS resident version of TURBO C had been submitted for validation, but was unlikely to succeed.

Babbage has plans to add a printer to the engine but the price, an estimated 200,000, could prove prohibitive to some small business users. Babbage claimed that the price would fall when the engine was in mass production. The printer is capable of 30 CPS with daisywheel quality.

The Manual for the engine is rather confusingly titled "Making a difference - Charles Babbage and the Birth of the Computer: The catalogue". It is pleasing to note that it complies with the Microsoft convention in that it devotes much of its content to the life and times of Charles Babbage and is totally lacking in any operating instructions. We were later told that there had been a "mix up at the printers" and that the real manual would be "available shortly"

In conclusion, the engine seems doomed to failure. It is not IBM compatible; it's slow; it needs a crane to move it; each engine takes a year to build; it costs 290,000, and a firm understanding of mathematics is needed to program it. But there are several interesting innovations: the low radiation flicker free display, low overall power consumption and rugged construction might find an application in battlefield or possibly airborne use (the latter being the one application where it has a performance advantage). The IT directorate of Messibeast have suggested that its high cost and technical obsolescence render it ideal for technical computing applications throughout the company.

Babbage has produced another truly British invention in a long line stretching from Brunel's Atmospheric Railway to Sinclair's C5. Has Babbage made a dreadful mistake in aiming the engine at small business users? Should he have stuck to governments and large corporate users? Only time will tell.

I will leave you with a final word from Babbage himself: "Look here young man, this is a British invention, built in Britain, and as a British citizen you should be..."

Copyright 1991, Peter D Rieden


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