A GENERATION of youngsters in Britain learned to program during the 1980s courtesy of the BBC Micro, developed by Acorn Computers of Cambridge for the BBC’s computer literacy project. American teenagers did much the same with the Commodore 64. At the time, your correspondent could not afford the $595 for a Commodore, let alone the £335 (equivalent to $800 at the time and over $2,000 today) for the more practical version of the BBC Micro. At more than $1,300, the Apple II was completely out of the question. But for £50, enthusiasts adept at wielding a soldering iron could construct a Sinclair ZX81 from a kit. Your correspondent built two, one for himself and another for a friend’s 11-year-old son.
In hindsight, the best part about the ZX81 was, ironically, its limited amount of storage. Having to write programs that could fit within the featherweight machine’s one kilobyte of RAM demanded serious thought. Simply displaying a screen-full of data took up three-quarters of the RAM. Even so, one enthusiast actually wrote a whole chess game in a kilobyte. Sinclair owners viewed the 32 kilobytes of the BBC Micro or the 64 kilobytes of a Commodore 64 as unimaginable luxury. But had they been given such an amount of memory, they might have written sloppier code.
Clive Sinclair (later knighted for his part in dragging Britain into the technological age) wanted to produce the cheapest computer possible, so schools and parents could afford to buy one for each child. The ZX81 came with a built-in keyboard but no screen nor any permanent means of storage. An audio cassette recorder served, somewhat erratically, as the latter. To display data, the ZX81 had to be plugged into a TV’s antenna socket and the set tuned to a vacant UHF channel.
Various tricks were used to keep the busy little computer running. One of the more memorable stunts was to place a bottle of cold milk on top of the ZX81’s black plastic case, just above the ULA (uncommitted logic array). This programmable chip did the work normally performed at the time by 18 separate devices—and, not surprisingly, tended to get hot. All told, the ZX81 contained only four integrated circuits. Its nearest rival in processing power, the Radio Shack TRS-80, needed no fewer than 44 separate chips.
Since those early days of home computing, your correspondent had never seen such minimalism in computing until the Raspberry Pi arrived on the scene a little over a year ago. This tiny bare-bones Linux computer, no bigger than a credit-card, costs $25 in basic Model A form. Model B, with a built-in network adapter plus an Ethernet port, a second USB socket and double the amount of RAM (512 megabytes), costs just $35.
Your correspondent instantly put his name down for a pair of Model B boards with one of the two distributors licensed by the Raspberry Pi Foundation, a charitable organisation linked to Cambridge University. Over the past year, he has periodically checked back with the distributor in New Jersey to see where on the waiting list he might be. After giving up all hope, out of the blue came a single Model B last week. It is all he imagined: computing stripped to its bare essentials. For an erstwhile Sinclair hacker, the Raspberry Pi is déjà vu all over again.
The Raspberry Pi comes without a keyboard or a mouse. Nor does it include a power supply (an old mobile-phone charger usually suffices). And like the Sinclair ZX81, it also lacks a screen—and has to be plugged into a TV or computer monitor. As well as sockets for analogue video and audio, the tiny board includes an HDMI port for streaming high-definition digital television to an HDTV set.
The key to the Raspberry Pi’s compactness is the use of a system-on-a-chip from Broadcom, which combines a frugal ARM 11 central processing unit with a graphics processor and (in the Model B) 512 megabytes of memory. Instead of a hard-drive, a slot for an SD card acts as the main form of storage. As with the peripherals and cables, users have to supply their own SD card.
The computer also comes without an operating system, which first has to be downloaded onto a PC or Macintosh, and the image then written to a formatted SD card. The Raspberry Pi website (www.raspberrypi.org) provides all the necessary software, along with ample instructions. Before trying other operating systems, users are advised to start with Raspbian—a Linux build based on the bullet-proof Debian 6.0 distribution that has been tailored especially for the little computer.
The Raspberry Pi is the brainchild of a couple of computer scientists at Cambridge University. Back in 2006, they lamented the decline in programming skills among applicants for computer-science courses. “It’s a problem for universities,” says Eben Upton, co-founder of the Raspberry Pi project and nowadays a trustee of the non-profit foundation that manages the programme.
The problem is not a lack of interest, but the lack of cheap, programmable hardware for teenagers to cut their teeth on. For typical youngsters, computers have become too complicated, too difficult to open (laptops especially) and alter their settings, and way too expensive to tinker with and risk voiding their warranty by frying their innards.
For that reason, Dr Upton and his colleagues have made some pretty serious programming languages—including Python, Basic, C and Perl—available for the Raspberry Pi. Initially, the computer boots straight into a command line. Before the Macintosh, Windows and other graphical user-interfaces hid commands behind icons that took the drudgery out of getting a computer to perform a user’s bidding, learning to concatenate cryptic commands helped fledgling programmers understand the inner workings of computers.
For those who prefer a Windows-like desktop, Raspbian can be tweaked to boot directly into LXDE, a lightweight graphical user-interface. Once there, the Raspberry Pi behaves like any other user-friendly computer, complete with a browser, a word-processor, plus all the usual productivity tools and games capable of being launched with a click of a mouse.
Many users may stop there. That would be a pity. For the Raspberry Pi can do practically anything a Linux desktop can do, albeit at a much more pedestrian pace. Overall, it performs like a Pentium computer from the late 1990s, but with bang up-to-date graphics.
But using the Raspberry Pi as a general-purpose computer is missing the point. The designer’s original brief was to create, not simply a much cheaper computer, but a hacking and teaching tool for school children. Rather than make it run faster or become easier to operate, Dr Upton wants to see it boot straight into a programming environment such as Scratch, a language developed by the Lifelong Kindergarten Group at the Massachusetts Institute of Technology.
Your correspondent occasionally has the urge to learn a new programming language. But at his superannuated stage of life, he has neither the time nor the need for such a skill. Tinkering with hardware, however, sounds a lot more satisfying.
For starters, he plans to turn his existing Raspberry Pi into a media centre. By all accounts, Raspbmc—a Linux-based operating system derived from the XBox game-player’s media centre—is a pretty powerful media player. The first task, then, is to rig the Raspberry Pi up so it can pluck video off the internet, via a nearby WiFi router, and stream it direct to a TV in the living room. Finding out not whether, but just how well, this minimalist little computer manages such a feat will be all part of the fun. Your correspondent likes to think that Sir Clive, hacker emeritus, would give an encouraging nod.
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