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Amiga Preview

Chris Jenkins and Simon Trask examine the musical implications of Commodore’s 16-bit monster computer. Will it be simply a haven for the gamesters and the accountants, or will it find a place on the shelves of music shops?


Spearheaded by front-runners like the Commodore Amiga and Atari's ST, the new generation of home micros aims to tempt more musicians into taking the computerised route. Do the machines have what it takes to succeed?


Computer Music is a difficult phrase. Does it imply Stockhausenesque warblings, without recognisable rhythm or harmony? Does it conjure up images of the beeping and whooshing of home computers, their internal sound chips pressed into musical service when their original purpose in life was to make sound effects for games? Or does it bring to mind Mr Horn and his ZTT collaborators, turning computers into musicians and musicians into nothing more than faces for the front covers of teeny-bopper magazines?

Whatever your view of it, you can't ignore computer music. You can't ignore, either, the rapid technological developments that are making the computers cheaper and their musical capabilities much, much more wide-ranging.

Of the current crop of new 16-bit home computers, the Commodore Amiga has been the one to generate the most fuss. Which is odd, because it's also the machine about which least is known. There's still an awful lot of mystery surrounding the Amiga, and on this side of the Atlantic, at least, that mystery is unlikely to be solved until the machine comes to this country in the new year.

The new Commodore has a long and chequered history, but once it is finally launched, its synthesis, sampling and control capabilities, combined with unheard-of graphics power, will make it a mouth-watering prospect for musicians of all inclinations.

The Amiga was born as a project of the Amiga Corporation, a company bought out by home computer giants Commodore International in order to gain control of the unique chip designs the smaller firm had developed. The resulting machine, the Commodore Amiga, uses the same 68000 main processor as the Apple Macintosh and Sinclair QL (not to mention upmarket musical instruments like the Kurzweil 250 and Series III Fairlight), but is in all important respects a completely different machine.

What makes the Amiga unique is its three custom chips, codenamed Agnus, Daphne and Portia, which control graphics, sound and data handling, leaving the main 68000 to operate at an unusually high speed without interruption.

But the Amiga is far from being a music-only (or even music-biased) device. It's a general-purpose business and creativity machine with some astonishing capabilities in all departments, so to give you a wider idea of the Amiga's overall potential, let's take a quick look at them before we get on to the music applications.

The standard machine has 256K of memory, expandable to 512K. There's an 89-key keyboard with numeric keypad, cursor and special function keys, a 4096-shade colour display with up to 640x400 pixel resolution, parallel and serial ports, a built-in 3.5-inch 880K floppy disk drive, an expansion port for extra drives, two joystick ports, built-in speech synthesis, optional IBM-compatibility, a video interface, an optional MIDI interface and keyboard, a window/icon/mouse operating system, and four-channel sound synthesis built in.

That's just for starters. The Amiga also features a disk operating system so fast it makes the IBM PC look like a ZX81, an advanced form of the BASIC programming language, and the all-important multi-tasking, the facility by which computers can work on more than one job at a time without having to drop one task altogether in order to accommodate a new one. In other words, the Amiga does everything better than any other computer on the market in its price range, it does it faster, and it does it all at the same time.

As a music machine, the Amiga is supplied with most of the hardware you'll find in multi-thousand pound systems like the Fairlight — QWERTY keyboard, optional music keyboard, disk storage, video display and so on. Internally, things aren't exactly up to state-of-the-art standards, but they're not far off. The Amiga's sound chip (Portia) uses digital techniques to synthesise waveforms. As in the Yamaha DX series synths, these waves can be combined to form complex sounds. There are four sound channels, each of which can be programmed independently, either through BASIC or through some powerful software packages which, we're told, will be available soon after the machine's official release. Each memory channel contains an eight-bit digital-to-analogue converter driven by a direct memory access (DMA) channel. The audio DMA can retrieve two data samples during each horizontal video scan line, so the Amiga can play complex music whilst still creating stunning graphics.

The waveform used by each sound channel can be defined in BASIC by entering data describing the shape of one cycle. When defining waveforms, you have to remember that, as with looping sampled sounds, it's important that the start and end values are similar if you want to create a smooth looping effect. Sound data is organised as a set of eight-bit data items, and sample values can range from —128 to +127.

Once you've stored the waveshape data, and told the system where to locate it, the volume is set in the six-bit volume register (values 0 to 64). This register can be controlled dynamically to create complex envelopes.

To specify the pitch, you have to set the frequency value, between 124 and 65535. The Amiga manual explains how these quantities correspond to musical scales.

When the DMA is enabled, the sound plays until disabled. For intricate and/or off-the-wall effects, you can splice different waveforms together, or modulate the frequency or volume of one channel with another. A low-pass filter is included to cut down aliasing distortion, but worryingly, rumours of these filters cutting off everything above 7.5kHz are as rife as ever. If they're accurate, the Amiga's bandwidth is going to be too limited for it to be competitive with what dedicated sampling machines, for instance, can currently offer.



Simple, yes? Well, maybe not — but this is where the forthcoming commercial software comes into the picture. With luck, it'll take all the difficult programming tasks off your hands.

Cherry Lane Technologies have already begun marketing three packages in the US. 'Harmony' takes an audio input — say a saxophone, as used at the Amiga's New York launch — and uses artificial intelligence techniques to create an auto-accompaniment section which actually plays along with your music, changing tempo to match yours, changing pitch, and controlling MIDI instruments.

'Scorewriter' is more prosaic but potentially more useful to professional musicians. As its name suggests, it's a high-level music transcription and sound-generation program ideally aimed at composers and music students. This is the sort of thing the Amiga's graphics facilities should make mincemeat of, so it'll certainly be worth checking out.

'Texture' is a 'musical word processor' developed originally for the IBM PC. It allows sequences to be created, filed, combined, edited and played, with full graphic accompaniment, and up to 16 musical voices playing simultaneously.

Another company, Everyware, has developed a synthesis program called 'Musicraft', which effectively turns the Amiga into a four-voice synthesiser and sequencer. It allows you to play the QWERTY keyboard the way you would a piano, using various preset voices or new sounds created by altering the waveform, harmonics, the eight-stage envelope, portamento, LFO, filtering and phasing.

What everyone is waiting for, of course, are the two developments which will make the Amiga a genuine computer musical instrument. First, although a MIDI interface is available, no full-spec MIDI software has yet been developed to enable the Amiga to control synthesisers. Second, although sound-sampling demonstrations have impressed computer journalists, there's no news on the official release date of the sampling hardware and software.

Tantalised by the sound of saxophones, guitar chords, banjos, explosions, Boeing 747s and tom-toms issuing from demo machines at the Personal Computer World show this summer, some of us put down a deposit on an Amiga immediately. It might be wise, though, to put the rumour that the Amiga is 'Fairlight data compatible' into perspective. True, Fairlight were originally responsible for the sound samples that currently reside in the Amiga's memory, so the two data formats must have been sufficiently compatible for the sample data to be transferred (presumably from a 16-bit Fairlight Series III) to the Commodore. But there's no indication that Fairlight sample disks and auxiliary data will be directly interchangeable with those of the Amiga — though who knows what the future holds?

At around £1 500, the Amiga represents a system which could theoretically make most electronic musical instruments obsolete. It won't, of course, because too many musicians are scared off by the idea of having to become computer-literate in order to make music. That's a process that isn't necessary these days because, to a large extent, if you can operate a Yamaha QX1, you can operate a home micro. Nonetheless, for as long as people prefer their machines to say 'musical instrument' on the front panel rather than 'home computer', products like the Amiga will have a limited impact on the music world.

The enlightened minority, meanwhile, will shortly be able to avail themselves of a machine that can synthesise complex polyphonic sounds; sample real sounds; control external instruments through MIDI and be controlled via the same route; store huge amounts of sound and control data; manipulate real video images through its 'genlock' system; superimpose high-resolution computer graphics, animations and digitised pictures; and do your accounts into the bargain.

As for Commodore themselves, they could soon have a monster on their hands. Apart from marketing the Amiga as a business micro, a Computer-Aided Design workstation and a mind-blowing games machine, demand from forward-thinking musicians could force the company to go into the music business, too.

DATAFILE - Commodore Amiga Personal Computer

Processors 68000 plus three proprietary designs, Agnus, Daphne and Portia

Memory 256K, expandable to 512K

Hardware Built-in 3.5-inch floppy, mouse, QWERTY keyboard; optional extra 3.5- or 5.25-inch floppies or hard disk; modem, printers, music keyboard, MIDI interface, video genlock, IBM emulator hardware

Interfacing Serial & parallel ports, stereo audio, joystick (2), 68000 expansion, extra drive port

Graphics Up to 4096 colours, up to 640x400 resolution

Sound Four-channel Portia sound chip with user-defined waveforms, filtering, envelopes, pitch and modulation; sampling option, details unconfirmed; stereo outputs

Price £1500 for basic system, subject to dollar fluctuation, available January

More from Commodore Business Machines, (Contact Details)


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TechTalk

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Atari ST Front End


Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.

 

Electronics & Music Maker - Jan 1986

Scanned by: Stewart Lawler

Hard Facts, Soft Options

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