Review: Centre For Computing History

With almost everything that contains a shred of automation relying on a microcontroller these days, it’s likely that you will own hundreds of microprocessors beside the obvious ones in your laptop or phone. Computing devices large and small have become such a part of the fabric of our lives that we cease to see them, the devices and machines they serve just work, and we get on with our lives.

It is sometimes easy to forget then how recent an innovation they are.  If you were born in the 1960s for example, computers would probably have been something spoken in terms of the Space Race or science fiction, and unless you were lucky you would have been a teenager before seeing one in front of you.

Having seen such an explosive pace of development in a relatively short time, it has taken the historians and archivists a while to catch up. General museums have been slow to embrace the field, and specialist museums of computing are still relative infants in the heritage field. Computers lend themselves to interactivity, so this is an area in which the traditional static displays that work so well for anthropological artifacts or famous paintings do not work very well.

There's the unobtrusive sign by the level crossing, Cambridge's version of the black mailbox.
There’s the unobtrusive sign by the level crossing, Cambridge’s version of the black mailbox.

Tucked away next to a railway line behind an industrial estate in the city of Cambridge, UK, is one of the new breed of specialist computer museum. The Centre for Computing History houses a large collection of vintage hardware, and maintains much of it in a running condition ready for visitors to experiment with.

Finding the museum is easy enough if you are prepared to trust your mapping application. It’s a reasonable walk from the centre of the city, or for those brave enough to pit themselves against Cambridge’s notorious congestion there is limited on-site parking. You find yourself winding through an industrial park past tile warehouses, car-parts shops, and a hand car wash, before an unobtrusive sign next to a railway level crossing directs you to the right down the side of a taxi company. In front of you then is the museum, in a large industrial unit.

Pay your entrance fee at the desk, Gift Aid it using their retro green screen terminal application if you are a British taxpayer, and you’re straight into the exhibits. Right in front of you surrounding the café area is something you may have heard of if you are a Hackaday reader, a relatively recent addition to the museum, the Megaprocessor.

The Megaprocessor, playing Tetris
The Megaprocessor, playing Tetris

If we hadn’t already covered it in some detail, the Megaprocessor would be enough for a long Hackaday article in its own right. It’s a 16-bit processor implemented using discrete components, around 42,300 transistors and a LOT of indicator LEDs, all arranged on small PCBs laid out in a series of large frames with clear annotations showing the different functions. There is a whopping 256 bytes of RAM, and its clock speed is measured in the KHz. It is the creation of [James Newman], and his demonstration running for visitors to try is a game of Tetris using the LED indicators on the RAM as a display.

To be able to get so up close and personal with the inner workings of a computer is something few who haven’t seen the Megaprocessor will have experienced. There are other computers with lights indicating their innermost secrets such as the Harwell Dekatron, but only the Megaprocessor has such a clear explanation and block diagram of every component alongside all those LED indicators. When it’s running a game of Tetris it’s difficult to follow what is going on, but given that it also has a single step mode it’s easy to see that this could be a very good way to learn microprocessor internals.

The obligatory row of BBC Micros.
The obligatory row of BBC Micros.

The first room off the café contains a display of the computers used in British education during the 1980s. There is as you might expect a classroom’s worth of Acorn BBC Micros such as you would have seen in many schools of that era, but alongside them are some rarer exhibits. The Research Machines 380Z, for example, an impressively specified Z80-based system from Oxford that might not have the fame of its beige plastic rival, but that unlike the Acorn was the product of a company that survives in the education market to this day. And an early Acorn Archimedes, a computer which though you may not find it familiar you will certainly have heard of the processor that it debuted. Clue: The “A” in “ARM” originaly stood for “Acorn”.

The LaserDisc system, one you won't have at home.
The LaserDisc system, one you won’t have at home.

The rarest exhibit in this froom though concerns another BBC Micro, this time the extended Master System. Hooked up to it is an unusual mass storage peripheral that was produced in small numbers only for this specific application, a Philips LaserDisc drive. This is one of very few surviving functional Domesday Project systems, an ambitious undertaking from 1986 to mark the anniversary of the Norman Domesday Book in which the public gathered multimedia information to be released on this LaserDisc application. Because of the rarity of the hardware this huge effort swiftly became abandonware, and its data was only saved for posterity in the last decade.

The main body of the building houses the bulk of the collection. Because this is a huge industrial space, the effect is somewhat overwhelming, as though the areas are broken up by some partitions you are immediately faced with a huge variety of old computer hardware.

The largest part of the hall features the museum’s display of home computers from the 1980s and early 1990s. On show is a very impressive collection of 8-bit and 16-bit micros, including all the ones we’d heard of and even a few we hadn’t. Most of them are working, turned on, and ready to go, and in a lot of cases their programming manual is alongside ready for the visitor to sit down and try their hand at a little BASIC. There are so many that listing them would result in a huge body of text, so perhaps our best bet instead is to treat you to a slideshow (click, click).

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Definitely not Pong, oh no.
Definitely not Pong, oh no.

Beyond the home micros, past the fascinating peek into the museum’s loading bay, and there are a selection of arcade cabinets and then a comprehensive array of games consoles. Everything from the earliest Pong clones to the latest high-powered machines with which you will no doubt be familiar is represented, so if you are of the console generation and the array of home computers left you unimpressed, this section should have you playing in no time.

One might be tempted so far to believe that the point of this museum is to chart computers as consumer devices and in popular culture, but as you reach the back of the hall the other face of the collection comes to the fore. Business and scientific computing is well-represented, with displays of word processors, minicomputers, workstations, and portable computing.

The one that started it all
The one that started it all

On a pedestal in a Perspex box all of its own is something rather special, a MITS Altair 8800, and a rare example for UK visitors of the first commercially available microcomputer. Famously its first programming language was Microsoft BASIC, this machine can claim to be that from which much of what we have today took its start.

In the corner of the building is a small room set up as an office of the 1970s, a sea of wood-effect Formica with a black-and-white TV playing period BBC news reports. They encourage you to investigate the desks as well as the wordprocessor, telephone, acoustic coupler, answering machine and other period items.

UK phone afficionados would probably point out that office phones were rearely anything but black.
UK phone aficionados would probably point out that office phones were rarely anything but black.

The museum has a small display of minicomputers, with plenty of blinkenlight panels to investigate even if they’re not blinking. On the day of our visit one of them had an engineer deep in its internals working on it, so while none of them were running it seems that they are not just static exhibits.

Finally, at various points around the museum were cabinets with collections of related items. Calculators, Clive Sinclair’s miniature televisions, or the evolution of the mobile phone. It is these subsidiary displays that add the cherry to the cake in a museum like this one, for they are much more ephemeral than many of the computers.

This is one of those museums with so many fascinating exhibits that it is difficult to convey the breadth of its collection in the space afforded by a Hackaday article.

There is an inevitable comparison to be made between this museum and the National Museum of Computing at Bletchley Park that we reviewed last year. It’s probably best to say that the two museums each have their own flavours, while Bletchley has more early machines such as WITCH or their Colossus replica as well as minis and mainframes, the Centre for Computing History has many more microcomputers as well as by our judgement more computers in a running and usable condition. We would never suggest a one-or-the-other decision, instead visit both. You won’t regret it.

The Centre for Computing History can be found at Rene Court, Coldhams Road, Cambridge, CB1 3EW. They are open five days a week from Wednesday through to Sunday, and seven days a week during school holidays. They open their doors at 10 am and close at 5 pm, with last admissions at 4 pm. Entry is £8 for grown-ups, and £6 for under-16s. Under-5s are free. If you do visit and you are a UK tax payer, please take a moment to do the gift aid thing, they are after all a charity.

Retrotechtacular: Stereo Records

The 20th century saw some amazing technological developments. We went from airplanes to the moon. We went from slide rules to digital computers. Crank telephones to cell phones. But two of the most amazing feats of that era were ones that non-technical people probably hardly think about. The transformation of radio and TV from mono and black and white, to stereo and color. What was interesting about both of these is that engineers managed to find a way to push the new better result into the same form as the old version and — this is the amazing part — do it in such a way that the old technology still worked. Maybe it is the rate that new technology moves today, but we aren’t doing that today. Digital TV required all-new everything: transmitters, receivers, frequencies, and recording gear. Good luck trying to play the latest video game on your 25-year-old PC.

It is hard to remember when stores were full of all sorts of audio and video media. We’ve noticed that all forms of media are starting to vanish. Everything audio and video are all streamed or downloaded these days. Records, 8-tracks, cassettes, and even CDs and DVDs are vanishing. However, vinyl records have made a come back in the last few years for their novelty or nostalgic value.

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Low Background Steel — So Hot Right Now

The nuclear age changed steel, and for decades we had to pay the price for it. The first tests of the atomic bomb were a milestone in many ways, and have left a mark in history and in the surface of the Earth. The level of background radiation in the air increased, and this had an effect on the production of steel, so that steel produced since 1945 has had elevated levels of radioactivity. This can be a problem for sensitive instruments, so there was a demand for steel called low background steel, which was made before the trinity tests.

The Bessemer process pumps air through the iron to remove impurities.

The production of steel is done with the Bessemer process, which takes the molten pig iron and blasts air through it. By pumping air through the steel, the oxygen reacts with impurities and oxidizes, and the impurities are drawn out either as gas or slag, which is then skimmed off. The problem is that the atmospheric air has radioactive impurities of its own, which are deposited into the steel, yielding a slightly radioactive material. Since the late 1960s steel production uses a slightly modified technique called the BOS, or Basic Oxygen Steelmaking, in which pure oxygen is pumped through the iron. This is better, but radioactive material can still slip through. In particular, we’re interested in cobalt, which dissolves very easily in steel, so it isn’t as affected by the Bessemer or BOS methods. Sometimes cobalt is intentionally added to steel, though not the radioactive isotope, and only for very specialized purposes.

Recycling is another reason that modern steel stays radioactive. We’ve been great about recycling steel, but the downside is that some of those impurities stick around.

Why Do We Need Low Background Steel?

Imagine you have a sensor that needs to be extremely sensitive to low levels of radiation. This could be Geiger counters, medical devices, or vehicles destined for space exploration. If they have a container that is slightly radioactive it creates an unacceptable noise floor. That’s where Low Background Steel comes in.

A person is placed into a low background steel container with sensitive equipment to measure the radioactivity of the body, which may be near the background level. Photo from

So where do you get steel, which is a man-made material, that was made before 1945? Primarily from the ocean, in sunken ships from WWII. They weren’t exposed to the atomic age air when they were made, and haven’t been recycled and mixed with newer radioactive steel. We literally cut the ships apart underwater, scrape off the barnacles, and reuse the steel.

Fortunately, this is a problem that’s going away on its own, so the headline is really only appropriate as a great reference to a popular movie. After 1975, testing moved underground, reducing, but not eliminating, the amount of radiation pumped into the air. Since various treaties ending the testing of nuclear weapons, and thanks to the short half-life of some of the radioactive isotopes, the background radiation in the air has been decreasing. Cobalt-60 has a half-life of 5.26 years, which means that steel is getting less and less radioactive on its own (Cobalt-60 from 1945 would now be at .008% of original levels). The newer BOS technique exposes the steel to fewer impurities from the air, too. Eventually the need for special low background steel will be just a memory.

Oddly enough, steel isn’t the only thing that we’ve dragged from the bottom of the ocean. Ancient Roman lead has also had a part in modern sensing.

Retrotechtacular: Tinkertoy and Cordwood in the Pre-IC Era

It is widely accepted that Gutenberg’s printing press revolutionized thought in Europe and transformed the Western world. Prior to the printing press, books were rare and expensive and not generally accessible. Printing made all types of written material inexpensive and plentiful. You may not think about it, but printing–or, at least, printing-like processes–revolutionized electronics just as much.

In particular, the way electronics are built and the components we use have changed a lot since the early 1900s when the vacuum tube made amplification possible. Of course, the components themselves are different. Outside of some specialty and enthusiast items, we don’t use many tubes anymore. But even more dramatic has been how we build and package devices. Just like books, the key to lowering cost and raising availability is mass production. But mass producing electronic devices wasn’t always as easy as it is today.

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How Many Inventors Does It Take To Invent A Light Bulb

Many credit the invention of the incandescent light bulb with Edison or Swan but its development actually took place over two centuries and by the time Edison and Swan got involved, the tech was down to the details. Those details, however, meant the difference between a laboratory curiosity that lasted minutes before burning out, and something that could be sold to consumers and last for months. Here then is the story of how the incandescent light bulb was invented.

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Retrotechtacular: How Old is the Remote?

A few weeks ago we covered a (probably) bogus post about controlling a TV with the IR from a flame. That got us thinking about what the real origin of the remote control was. We knew a story about the 38 kHz frequency commonly used to modulate the IR. We’ve heard that it was from sonar crystals used in earlier sonic versions of remotes. Was that true? Or just an urban myth? We set out to find out.

Surprise! Remotes are Old!

If you are a younger reader, you might assume TVs have always had remotes. But for many of us, remotes seem like a new invention. If you grew up in the middle part of the last century it is a good bet you were your dad’s idea of a remote control: “Get up and turn the channel!” Turns out remotes have been around for a long time, though. They just weren’t common for a long time.

If you really want to stretch back, [Oliver Lodge] used a radio to move a beam of light in 1894. In 1896, [Marconi] and some others made a bell ring by remote control. [Tesla] famously showed a radio-controlled boat in 1898. But none of these were really remote controls like we think of for a television.

mysteryOf course, TV wouldn’t be around for a while, but by the 1930’s many radio manufacturers had wired remotes for radios. People didn’t like the wires, so Philco introduced the Mystery Control in 1939. This used digital pulse coding and a radio transmitter. That’s a fancy way of saying it had a dial like an old telephone. As far as we can tell, this was the first wireless remote for a piece of consumer equipment.

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Two Bits a Gander: Of Premature Babies, Incubators, and Coney Island Sideshows

Newborn humans are both amazingly resilient and frighteningly fragile creatures. A child born with a 40 full weeks of gestation has pretty good odds of surviving the neonatal period these days, and even if he or she comes along a few weeks early, things usually go smoothly. But those babies that can’t wait to get out and meet the world can run into trouble, and the earlier they’re born, the greater the intervention needed to save them.

We’ve all seen pictures of remarkably tiny babies in incubators, seemingly dwarfed by the gloved hands of an anxious parent who just wants that first magical touch of their baby’s skin. As common as such an intervention is now and as technologically advanced as neonatology is, care for premature infants as a medical discipline has a long and interesting history of technical and social hacks that’s worth looking at.

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