News article: The 20 most important computers of all time

It might sound more like a sports car than a computer but the Panasonic was an excellent machine for musicians at the time, as it was able to produce CD-quality samples (although not for very long) and had a built-in Midi adaptor, announced in sparkly writing just above the keyboard, which meant it could drive synthesizers. As some old musicians and synth enthusiasts from the 1980s now have proper jobs or regular royalty cheques, the MSX is enjoying high resale values.

The Alto was the first computer to feature a graphical desktop, the inspiration for both the Macintosh OS and Microsoft Windows, making it an enormously influential machine. Xerox themselves failed to capitalise on their innovation, leaving it to other companies to revolutionise computing while they concentrated on making photocopiers and laser printers. The Xerox Star was a direct descendant of the Alto intended for a wider market, but failed to sell well in the face of stiff competition from so many other companies that had adopted graphical user interfaces. Xerox can take some solace from the respect paid to the Alto by computer collectors, for whom it is one of the few machines that are currently unavailable at any price.

The Lisa was Apple's first (anyone's first, in fact) personal computer to be operated using a graphical interface. It had a mouse, pull-down menus and windows, there were 5.25in disk drives and a whole megabyte of RAM. Think of it, a whole megabyte, who could possibly need more than that? Costing almost $10,000 it was not a big seller, and was discontinued after just a year. The hardware lived on as the Macintosh XL, but the Lisa OS was replaced by Macintosh OS and the twin 5.25in disk drives were succeeded by a single 3.5in unit.

The kit that made personal computing affordable, costing less than $500 in 1975, and inspired the generation of engineers and software developers that became the chiefs of Silicon Valley, some of the richest and most influential people on Earth. Its designer, Ed Roberts, only worked in electronics for a decade, retraining as a small-town family doctor after he sold his company in 1977. He died this week at the age of 68.

Steve Wozniak's Altair-inspired design started Apple from a bedroom and was funded by the sale of Steve Jobs's Volkswagen van. Around 200 were made, all by Wozniak himself, making it one of the very rarest of the machines on our list. It was sold as a completed circuit board but owners had to add their own keyboard, case, monitor and power set-up. The radical step away from machines such as the Altair was that the keyboard was the primary input device for the Apple 1. Ron Wayne, the third partner in the original business, handed back his 10 per cent of the company in exchange for $500 when he disagreed with Jobs over plans to borrow money to make more Apple 1s. His share would now be worth more than $20bn.

The Imsai 8080 was made famous by the 1983 film Wargames, in which Matthew Broderick almost-but-not-quite brings about the end of the world by hacking into a military nuclear war simulator. He does it using a customised version of the Imsai connected to the telephone lines through an acoustic coupler – a modem sporting rubber cups into which the ear and mouthpiece of a normal telephone were placed. The big coloured switches and flickering lights of the machine make it appealingly futuristic to look at in a 1970s sort of a way.

Launched in 1970, the Kenbak, which took its name from a contraction of that of its inventor, John Blankenbaker, is a very early personal computer. It was much cheaper than the expensive minicomputers of the time at $750, but still out of reach to all but the most prosperous enthusiasts. Input was by switches, output by blinking lights, so there were almost no practical applications, but its rarity and historical value are great.

For at least five years after Microsoft bought a licence to 86-DOS in 1980 (purchasing the full rights in 1981) and IBM agreed a licensing arrangement, the phrase 'IBM-compatible' was an essential requirement for any business machine. That IBM's PC manufacturing arm was sold to Lenovo, a Chinese company, in 2004 when it had only five per cent of the PC market, says more about Microsoft's ability to negotiate a first-class non-exclusive licensing deal than it does about IBM's influence on the computers that most of us use in our daily lives.

Steve Jobs left Apple in the mid-1980s to set up NeXT, a company that made computers for higher education and businesses. The NeXt Cube was launched in 1990 and manufactured until 1993. It was the computer used by Sir Tim Berners-Lee to create the first world wide web page and was the inspiration for Apple's G4 Cube. The NeXT operating system went on to become the foundation of Apple's OS X, a variation of which still powers today's Macs.

Launched in 1977, the PET was Commodore's first computer and various models were produced until 1982. Primarily used as education machines, the early PETs had built-in cassette drives for loading programs and tiny "chiclet" keyboards, which were hard to type on. Later versions hard larger keyboards.

Nowadays it seems that every new Apple product is a runaway success. The G4 Cube, inspired by the NeXT Turbo Dimension Cube, is their most recent failure. Despite achieving a cult status in recent years, the G4 Cube – released in 2000 – had disappointing sales and was sidelined in mid-2001.

Apple still calls its mid-range desktops iMacs but the classic iMac is the G3, the first computer produced after Jobs's return to Apple in 1997. Designed by Jonathan Ive, the iMac G3 had the computer hidden away as part of the monitor and encased in coloured, translucent plastic. Between 1998 and early 2003, when it was discontinued, the iMac reinvigorated Apple's image as a cool computer company and introduced the now familiar i-prefix for Apple products, of which the iPad is just the latest example.

Describing the Osborne 1 as a portable computer today seems laughable. Weighing 24.5 pounds – the equivalent of about five modern laptops – the Osbourne 1 had a five-inch, monochrome display and a keyboard that folded over to allow the computer to be carried like a suitcase. The Osborne 1 sold well from its launch in 1981 but eventually the computer began to lose ground to the rival Kaypro II. The Osborne Computer Company filed for bankruptcy in 1983.

The Digital Equipment Corporation introduced the PDP-8 minicomputer in 1965. Retailing for $18,500, the computer was DEC's most affordable to that point – the PDP-5 cost $27,000, while the PDP-6, built for the Massachusetts Institute of Technology, cost $300,000. Almost 1,500 were sold and DEC remained in business until the late 1990s, when it was acquired by Compaq.

Originally built in 1958 using vacuum tubes, the IBM 709 was a mainframe computer that cost $1 million. A later version of the machine was used for the US Ballistic Missile Early Warning System.

Envisaged as a cheaper version of the BBC Model B, the Acorn Electron was introduced in 1983. Production problems meant that sales were initially slow and as a result the Electron never really achieved mass-market success. However, software was still being produced for the computer until the early 1990s.

The BBC Micro was built by Acorn as a computer that the BBC could use for The Computer Programme, a show intended to educate the public in the growing importance of personal computing. More than 1.5 million BBC Micros, which came as the 16k Model A and the 32k Model B were sold. They were used in many British schools and remained in production until the early 1990s.

This tiny box with its strange rubber keys introduced many Britons to personal computing. Launched in 1982, the ZX Spectrum built on the success of the ZX81, released a year earlier. The 48k version sold at £175, while a cheaper 16k version was available for £125. The Spectrum brand was sold to Amstrad in 1986.

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From the Altair 8800 to the Apple iMac, here &ndash; in no particular order &ndash; is our   pick of the most significant machines in computing history