Popular culture is filled with examples of technological products that were heralded as ground-breaking but, due to the rate of development in the world of computing, went on to sink without a trace. Although some of them are best left forgotten, others were truly innovative.

Here we reveal five pieces of tech that were big in their time but fell by the wayside. In each case, though, their legacy is still with us today.

1. OS/2: The OS that wasn't

OS/2 was jointly developed by Microsoft and IBM as the primary operating system for the IBM PS/2. The PS/2, in turn, was IBM's second-generation personal computer architecture, launched in 1987 with the intention of clawing back market share from PC clone manufacturers.

It was a miserable failure, with customers preferring to stick with the regular PC architecture, but OS/2 remained. Back in the mid '80s and even into the '90s, it was at the cutting edge of OS technology.

OS/2

When OS/2 was launched, most computers were running DOS. This provided only a command-line interface. Except for running programs, it did little more than provide some mundane ways to copy, rename and delete files. User-friendly it certainly wasn't.

To stand any chance of success, IBM knew that OS/2 would have to support MS-DOS software. So it did, right from the start. From version 2.0 in 1992, it even had the power to run Windows applications as well, thanks to OS/2's support of Virtual DOS Machines (VDMs). Each of these could run a separate DOS program, which was all that Windows was at that time.

Today, virtualisation offers the possibility of running apps written for one OS under another. Many think this is a new feature, but OS/2 was providing a surprising degree of cross-platform support over 20 years ago.

The first version of OS/2 was text-only. A rather basic graphical interface, the Presentation Manager, was introduced with version 1.1. But with version 2.0, OS/2 gained what we would recognise as a Windows-like user interface that went by the name of Workplace Shell.

This was just one of the aspects in which OS/2 – and particularly OS/2 Warp, which launched in 1994 – attempted to court home users as well as computer professionals.

Another example was support for video playback, which was integrated into OS/2 from version 2.1 in 1993. By way of contrast, it took until Windows 95 for Microsoft to catch up (though add-ons were available earlier).

To think of OS/2 as merely an open-platform operating system with a future-looking user interface would be to do it a great disservice. Behind the scenes it was also breaking new ground in many other areas. OS/2 brought support for 32-bit processors to the desktop years before Windows 95. It offered multitasking, permitting several apps to run at the same time, and it provided an unprecedented level of security.

Prior to OS/2 it was quite possible for a badly behaved application to crash the entire PC. It's interesting to note that OS/2 version 3.0 never materialised, at least not under that name. Instead the technology saw the light of day – after a convoluted and murky development process – in the guise of Windows NT, which was aimed primarily at the server market and seen by many as the first 'serious' version of Windows.

Given that Windows 2000, XP, Vista and 7 are all based on the NT architecture, it's clear how much we owe to the ideas pioneered in OS/2.

2. Windows 3.1

Windows came to the PC in 1985, but it didn't exactly take the world by storm. Neither did versions 2.0 or 2.1, which followed in close succession. That privilege was reserved for Windows 3.1, which launched in 1992 and sold over two million copies in its first few months – a phenomenal achievement for an operating system.

In the early days of Windows, when you started up your PC you'd be presented with a DOS command line prompt such as 'C:/>'. You could then start a DOS program by typing its name, or you could start up Windows by typing WINDOWS.

The fact that Windows was started in this way indicated that it was little more than any other DOS program. Indeed, these early versions have been described as graphical front-ends rather than operating systems in their own right.

Windows 3.1

With Windows 3.x, especially the hugely popular Windows 3.1, all of this changed. Though Windows still required DOS to provide much of its core functionality, it became a platform in its own right. In some respects, Windows 3.1 didn't have the same level of sophistication as OS/2. But given that it proved far more successful in the marketplace, it too has had a major impact on the versions of Windows that followed in its wake.

Formerly, PC OSes imposed a limit of 640kB for user applications, but Windows 3.1 smashed through this barrier to give users access to up to 16MB. This might not sound a lot today, but in the days of 80286 and 80386 processors it was a vast amount. More importantly, the OS started the trend of ever-increasing memory availability.

Another of Windows 3.1's innovative features was support for TrueType fonts. Familiar names such as Arial, Times New Roman, Symbol and Windings are all with us still.

For the first time, the on-screen display was WYSIWYG ('what you see is what you get'), meaning that you could create a document on-screen in the sure knowledge that it would appear just the same when you printed it out. Today we take this for granted, but it was key to bringing desktop publishing to the mainstream.

Windows 3.1 also appeared in the guise of an enhanced version called Windows for Workgroups 3.1. This was much the same as the base version, but it also provided native networking support. PCs were suddenly able to share files and printers, an essential part of business computing.

Also included in this version were utilities for Messenger-like chatting and email. In the main these were used across a LAN rather than via the internet, but they were more examples of how this long-forgotten version of Windows was ahead of its time.

3. ICQ

Launched in 1996, ICQ (pronounced 'I Seek You') led the way in promoting web-based instant messaging. Now owned by AOL, but quite distinct from AIM (AOL Instant Messenger), ICQ is still around. We hear much less of this particular IM client today, yet modern counterparts owe much to its pioneering technology.

Despite its head start, it was commercial considerations that pushed ICQ into the margins. The likes of AIM, MSN Messenger (now Windows Live Messenger) and Skype entered the market from different angles, polished up the experience and ultimately proved to have more clout.

ICQ

AOL was one of the first to jump on the ICQ bandwagon – it launched its competitor just a few months after ICQ. Skype didn't appear on the scene until 2003, and initially its product was quite different in offering, being primarily a VoIP (Voice over Internet Protocol) service. But by then all the major textual instant-messaging clients were starting to add VoIP, and very soon the dividing lines got very indistinct.

Today, casual users will see little difference between the major products. In addition to textual instant messaging and VoIP, the vast majority of clients now offer video conferencing, a whiteboard so you can sketch as you chat and even photo sharing, file sharing and app sharing.

ICQ didn't represent the first steps in internet-based chat. For that we'd have to go back to 1988 and IRC (Internet Relay Chat), but that was subtly different from instant messaging. With IRC, you joined a channel to take part in a discussion among lots of people, many of whom you might not know. It was used extensively by the academics and enthusiasts who inhabited the internet in the early days.

ICQ broke new ground because its service restricted communications to your group of known contacts. ICQ's current market share may pale next to that of the big boys, but without it, instant messaging might never have been.

4. RealPlayer

Think streaming video on the web and you think Flash, right? Well, it hasn't always been that way. At one time, wherever you looked, the web was awash with RealVideo movies. True, RealVideo hasn't totally disappeared into oblivion, perhaps because the RealPlayer browser plug-in can also handle MPEG video and play DVDs, but the native RealVideo format is rarely encountered in the wild any more.

RealPlayer first hit the streets under the name of RealAudio in 1995. Although it was one of the first players capable of handling streaming media, it was capable of audio playback only. Support for video coincided with a name change to RealPlayer in 1997, and back then it was ahead of the field.

RealPlayer

For the first time, it was possible to watch video footage over the web in real-time rather than first having to download a video file and then play it back. In its first 24 hours of existence, over 100,000 copies of the software were downloaded. It's no exaggeration to say that the web hasn't been the same since.

In some ways, the reason for RealPlayer's early success is simply that it got there first. In such a fast moving market, a couple of years is a huge head start. Even so, before the end of the decade it was joined by Apple's QuickTime (which gained streaming support from version 4), Microsoft's Windows Media player (version 6), and Macromedia Flash (streaming video from version 4).

What's more, throughout the late '90s the RealVideo format was generally praised for the quality it could achieve at high compression ratios – an important factor in the days of dial-up networking.

Today Adobe has pretty much won the streaming video wars with its Flash Video format and plug-in. This success has been attributed to the plug-in's small download size and ease of installation, but its adoption by YouTube has probably proved more significant. Things could have been very different.

Being the first sometimes means launching a product before its time has really come. When RealPlayer came to market, under one per cent of British households could boast a broadband connection, and most people were using a 28k or 56k dialup service. As a result, streaming video was produced at resolutions as low as 160 x 120 pixels and a super slow frame rate.

By way of comparison, today's standard definition digital TV has a resolution of 720 x 576, and for HDTV the figure can be as high as 1,920 x 1,200. Streaming video on the web is now available in high-definition (YouTube, for example, provides up to 1,920 x 1,080 for users with at least 5MB/s bandwidth).

The technology may not use RealVideo itself, but it definitely owes it a debt.

5. Intel's MMX

The basic instructions that mainstream processors for the PC are able to execute are usually referred to as the x86 instruction set, which can trace its heritage back to the 8086 that appeared in 1978. It would be wrong to believe that today's core chips are only able to execute the same instructions as the 8086, though.

Although each x86 processor is backward-compatible with its predecessors – meaning that it can execute all of their instructions – new instructions have been introduced throughout the 32 years of the x86 processor's life.

Intel 8088

MMX was the name given to a whole group of additional instructions that were added to a Pentium variant launched in 1996. It could be argued that it was the most significant addition to the x86 instruction set since the migration from a 16-bit to a 32-bit architecture in 1985.

It's generally assumed that MMX stands for MultiMedia eXtension, although Intel has never confirmed this and some realistic alternatives have been suggested. The MMX instruction set comprises 47 'single instruction multiple data' (SIMD) instructions that operate on 64-bit registers.

Rather than operating on a single 64-bit value – an ability that was only introduced into the x86 instruction set with 64-bit processors – the MMX instructions work with multiple values packed into 64-bit registers. This permitted the instructions to use two 32- bit values, four 16-bit values or eight 8-bit values.

This level of parallelism is particularly useful in graphics processing, where it offers a substantial performance boost. It's also a trick that was employed in the specialist vector processors that were used by supercomputers for many years.

So why do we hear so little about MMX today? Not because it's been discontinued, but because it's been joined by other SIMD instructions that offer even greater performance benefits for multimedia apps.

First up was SSE (Streaming SIMD Extensions), a technology that made its debut in the 1999 Pentium III processor. It introduced 128-bit registers and a massive 70 new instructions. What's more, while MMX could only operate on integers (whole numbers), the SSE instructions are able to work on floating-point numbers as well.

Since then the technology has seen incremental enhancements to the architecture known as SSE2, SSE3, SSSE3 and SSE4, and AMD has introduced some extensions of its own. Plus yet more improvements are in the pipeline.

AVX (Advanced Vector Extension) was announced by Intel in 2008, and is expected to appear in processors soon. Initially it will feature 256-bit registers, although some pundits reckon that, in time, this will increase to 512 or even 1,024 bits.

Without the introduction of MMX, then, it's possible that the incredible feats of graphics technology we see today could never have been achieved. And that idea is something that's true to all the technologies we've discussed here. In computing it's always important to look to the future: but we mustn't forget to tip our hats to the past, either.

-------------------------------------------------------------------------------------------------------

First published in PC Plus Issue 295

Liked this? Then check out Thanks for the memory: the story of storage

Sign up for TechRadar's free Weird Week in Tech newsletter
Get the oddest tech stories of the week, plus the most popular news and reviews delivered straight to your inbox. Sign up at http://www.techradar.com/register

Follow TechRadar on Twitter * Find us on Facebook