After 25 years of the IBM PC, it's hard to remember that the IT system ever consisted of more than the binary system of the bloated red giant of Wintel and the sputtering white dwarf of Apple, with perhaps a few swarms of Linux distro asteroids cluttering up the place. Yet the past quarter-century has seen many other strange comets swing past, each offering a glimpse of what might have been.
Although it wasn't the only 16-bit computer launched in 1981, the IBM PC was the only one based on the Intel 8088 chip. Most opinion at the time favoured Motorola's 68000 processor, which had many claims to be the better design — and had IBM followed that path, it is very possible that Microsoft would not have been chosen as the software provider.
Nobody can say how IT history would have changed, but it's worth remembering that while the PC world was working its way slowly through moderate competencies such as the VGA adaptor and the early years of Windows, the 68K world had the Macintosh, the Amiga and the Atari ST. We cannot tell whether the state of the art in 2006 would be much further advanced, but we may confidently predict we'd have got here a lot quicker.
But IBM was by no means the worst of the class of 1981. History is mercifully silent on the ICL Personal Computer, launched with technology that was already geriatric. Other companies were also on their way out — Xerox with its slow 820, Tandy with its ageing TRS-80 range, Lucas with its end-of-an-era NASCOM-3 — while others were setting up for bursts of success of varying lengths.
Osborne demonstrated that portable need not mean light, while Acorn and Sinclair prepared the ground for revolutions yet to come with the BBC Micro and the ZX81. They provided the UK with a generation of adept programmers in a way that no subsequent designs have matched — but that's a subject for another time.
Of the 50-odd companies launching personal computers that year, only HP and Toshiba remain in the trade. Even IBM has left the building — rejected at length by the empire it built. Students of business and technology will argue for decades to come about IBM's mistakes and successes, but for richer or poorer, better or worse, we will be living with that company's legacy for years to come.