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A credit-card sized computer designed to help teach children to code has gone on sale for the first time.

The Raspberry Pi is a bare-bones, low-cost computer created by volunteers mostly drawn from academia and the UK tech industry.

Sold uncased without keyboard or monitor, the Pi has drawn interest from educators and enthusiasts.

Supporters hope the machines could help reverse a lack of programming skills in the UK.

"It has been six years in the making; the number of things that had to go right for this to happen is enormous. I couldn't be more pleased," said Eben Upton of the Raspberry Pi Foundation which is based in Cambridge.

Massive demand for the computer has caused the website of one supplier, Leeds-based Premier Farnell, to crash under the weight of heavy traffic.

School tools

The device's launch comes as the Department for Education considers changes to the teaching of computing in schools, with the aim of placing greater emphasis on skills like programming.

In a speech outlining those changes, Michael Gove mentioned the Pi, suggesting devices like it could play an important role in the kind of computer class the government envisages.

"Initiatives like the Raspberry Pi scheme will give children the opportunity to learn the fundamentals of programming," he said.

"This is a great example of the cutting edge of education technology happening right here in the UK."

Initially the £22 ($35) model of the Pi will be offered for sale. A cheaper £16 ($25) version will go on sale later in the year.

The machine, which runs on open-source operating system Linux, can be hooked up to a typical computer monitor - with additional ports used to attach a keyboard, mouse and other peripherals.

It also features an ethernet port, meaning the device can make use of high-speed internet connectivity.

Supporters hope the thousands-strong community of people that has grown up around the Pi will help develop additional software and suggest uses for the device.

The Pi going on general sale is likely to add to the buzz around the machine, but there are already a number of similar stripped-down computers on the market.

These include devices such as the Beagleboard and the Omnima MiniEMBWiFi.

Bottle-necks banished

The Raspberry Pi Foundation says it has already produced thousands of the machines, using a Chinese manufacturer.

It had originally hoped to produce the devices in the UK - "we want to help bootstrap the UK electronics industry" the group wrote in a blog post - but that turned out not to be possible at the right price.

But while production remains overseas, deals with two distributors, Premier Farnell and RS Components, mean that production volumes will be able to grow much faster than previously thought.

Rather than the foundation having to fund production, distributors have agreed to handle orders and deal with manufacturers paying the foundation a royalty on sales.

Dr Upton says that will help the project grow much more quickly than previously thought.

"We didn't realise how successful this was going to be," he said.

"This means we can scale to volume. Now we can concentrate on teaching people to program."