Graham Mellor is quite justified in saying that drastic changes have taken place since he opened A1 Music, as much has happened in the music industry over the past two decades both in the areas of live performance and recording. In the mid-sixties, the Beatles and the Rolling Stones were the only supergroups, a far cry from the star-studded charts of today. In those days record companies vied with each other for up and coming bands, but now the bands vainly pursue the record companies, who have to employ security staff to keep them out.

At a local level, bands (or groups as they were then exclusively called), flourished and every youth club and dance hall presented a live act at least once a week. Now only one area remains unchanged, and that is the dreadful social club circuit. Even then, bands were condemned to three sets an evening playing support to the bingo machine and the repertoire of favourites has barely changed - you can still hear Shadows instrumentals and old Spencer Davies numbers played to this day.

It's probably safe to say that at the time A1 Music was founded, the typical band consisted of two guitars, bass and drums, and you were doing well to own a thirty-watt Vox or Watkins amp. Fender guitars were unheard of in non-professional circles, and similarly, only the well-off could afford a good Burns guitar or perhaps a Gretsch. Mere mortals had to be content with cheaper models from the likes of Hofner, Framus, Futurama or Watkins... Roundwound bass strings had not yet been invented, and effects were limited to echo (usually courtesy of the legendary Watkins Copicat), though the first fuzz boxes were just starting to hit the market.

If anything, the rift between 'commercial junk' and the thinking man's pop music was even greater than it is today. Whilst the average pop fan was listening to 'Thank Your Lucky Stars' or drooling over Cathy McGowan presenting Ready Steady Go, the serious muso was into blues: John Mayall, The Pretty Things, or The Yardbirds.

Things started to change when The Who came on the scene. Bigger amps with the ridiculously high power of 100W were built, and the seeds of the high volume rock concert were sown.

Virtually all the present day rock giants paid their dues either with John Mayall's Blues Band or the Yardbirds (or both) including Eric Clapton, Jimmy Page, Jeff Beck and Mick Taylor, and the era of the supergroup was about to begin. Eric Clapton joined forces with Jack Bruce and Ginger Baker to form Cream, and within two hectic years, they changed the face of rock music, as well as making exceedingly large amounts of money into the bargain.

It was not until this time that the keyboard started to make serious inroads into rock and pop music. Previously there had only been the Hammond Organ (as played by the likes of Brian Auger and Wynder K Frogg), or the Vox Continental, popularised by Alan Price on the Animals' 'House of the Rising Sun'.

As the swinging sixties became the sinking seventies, ELP burst upon the scene with Keith Emerson's banks of specially-built Moog synths (as well as a few dummies) and started producing music the like of which the public had never heard before. Their stage shows probably instigated the trend towards rock theatre as practised by the likes of Jethro Tull, Genesis, The Sensational Alex Harvey Band, Yes and Pink Floyd.

These theatre performances often included spectacular lighting displays and slides or films projected on to the rear of the stage. The use of costumes and make-up was a further natural development, not only on stage, but also amongst the fans themselves. This in turn led to the creation of characters and dramatic action within the stage shows and the idea of a concept album such as David Bowie's The Rise and Fall of Ziggy Stardust and Genesis' The Lamb Lies Down on Broadway. Side by side with this development came the idea that rock stars could become stars of the screen as well. Concept albums such as The Who's Tommy and Pink Floyd's The Wall were admirably suited to cinematic production.

Mirrored in this diversity was the way in which more intricate music began to gain further acceptability in the rock world, with harmony, melody and rhythm all breaking new ground. Bands such as the aforementioned ELP employed five and seven time regularly, and even eleven and fourteen now and again. Yes also indulged in bitonality and simultaneous unrelated time signatures.

Other bands, such as Queen and 10cc, specialised in overlaying vocal harmonies, and texturally, hand in hand with the advent of new technology, sounds became richer and more varied. And not surprisingly, this gave more scope to individuals (such as Vangelis and Rick Wakeman) wanting to display specific personal timbres.

Heavy rock managed to survive through the seventies without any substantial changes, and its fans have now been banging their respective heads together for well over fifteen years, to the sound of bands such as Black Sabbath, Iron Maiden and Deep Purple.

During the second half of the seventies, punk burst like a time bomb on the rock music world, partly as a reaction against the complication and technological refinements of 'pomp rock'. Among punk's leading lights were bands such as the Sex Pistols, Ultravox, and The Damned. With punk came many connected subcultures and alternative fashions, yet despite (or because of?) this onslaught, the old dinosaurs continued to grow, and many older groups succeeded in selling more albums than ever. Nevertheless, many groups could not help but be influenced by the sheer raw energy of punk. Witness the directions taken by the likes of Genesis and Peter Gabriel since 1980.

More recently, music from all sorts of diverse cultures has also become a major influence on popular music. Reggae is probably the most widespread of these, but African, Indian and Oriental music have also played their part in affecting the varied course of rock. Again, the work of Peter Gabriel comes to mind.

As far as the eighties are concerned, the advance of micro technology has undoubtedly been the single most important factor in shaping the sound of popular music.

Nobody these days even so much as bats an eyelid at the thought of a band playing nothing but synthesisers, so great has been the onslaught of the electronic musical instrument. Once the pioneering work had been done by artists such as Brian Eno, Tangerine Dream, and Kraftwerk, the way was clear for Britain's charts to embrace modern technology fully. The continued success of Gary Numan, Depeche Mode and the second incarnation of Ultravox has inspired thousands of young musicians to take up the synthesiser as their only instrument, much to the chagrin of the guitar heroes of yesteryear.

And the future?

Well, the onslaught of technology continues unabated, with music computers - once the sole province of the rich and landed - being used by more and more musicians every day. Inspired by the work of Thomas Dolby, Peter Gabriel (yes, him again...), and Trevor Horn, electronic buffs and keyboard players alike await each new hardware and software release with eager anticipation.

Whatever else may be uncertain, there can be no doubt that modern technology should ensure that the next twenty years of popular music are just as exciting as the last, if not more so. And no dealer is paying more attention to that technology than Manchester's A1 Music...