Roland have several interesting new additions to their Amdek range this month, and are beginning to forge a link between music and a newly accessible form of heavyweight computing. Accordingly the new range includes a computer composition interface called Compu-Music, an analogue to digital interface, an X-Y chart plotter, and in addition a whole range of video display units.

First the CMU-800 Compu-Music, a computer peripheral half the size of an Apple which only requires an optional 'personality module' to make it compatible with almost any home computer, including Apple (slot 5), MZ-80K, 8032 Pet and so on.

Once connected to the computer and an amplifier the Compu-Music generates its own sounds for melody, bass, percussion and backing chords. The minimum 48K of RAM needed gives 9000 programme steps, which is sufficient for a composition about five minutes long, although for practicality and speed a disc drive for loading and storage will be found useful.

The outputs of the Compu-Music are as follows: Channel 1 is for melody, a preset sound with variable decay. Channel 2 is for bass, again with variable decay, and Channels 3 to 6 produce chords with a piano-like sound. In each case a control voltage and gate are available, which do not provide control over dynamics at the moment. Outputs are on standard 1V/octave scale.

Channel 7 is a synthesiser control output only, while Channel 8 is a control output with a portamento facility. In addition, there are individual audio outputs for bass, melody, chords, and for the rhythm section which draws on the same memory store as the other channels.

The rhythm section produces seven sounds, Snare Drum, Bass Drum, High and Low Toms, Crash, Open and Closed High-Hat, and is programmed in a similar manner to the familiar Doctor Rhythm. It can use 16 or any other number of beats in a bar, and like the other sections can be comprehensively edited, chained, looped and soon using the computer keyboard.

Tempo control is available on a front panel pot or there are clock in and out sockets for external rhythm machines, sequencers or arpeggiators. The computer VDU gives a constant display of the state of the composition on various pages, and reminds the user about the options available including Point Edit, Play, Loop Play, Change of Bias (for calibration with different external systems) and so on.

The Amdek ADA-200 is an Analogue-Digital-Analogue convertor peripheral, again compatible with most home computers, for instance via Slot 3 of an Apple. It has two channels which sample any analogue input, ranging from synthesisers to thermocouples, convert the input to an 8 bit digital code and make this available for computer manipulation.

Front panel controls give a wide range of options for AC/DC inputs, Trigger Level, and Position where an oscilloscope display is being used. The Sweep Trigger can activate an X-Y plotter for a hard copy of the display, and so for instance a microphone input can be digitised and displayed temporarily or recorded on paper permanently.

Nine different sample times are available with a bandwidth trade off in operation, so that 8 seconds gives 2kHz bandwidth whereas higher rates can give up to 18kHz bandwidth. Software is presently being written to increase the potential for manipulating the stored information, and it is hoped that Fairlight CMI-style sound reproduction will eventually be possible. A Wave Memory software package including an interface card is already available for storage of up to four waveforms.

The Amdek DXY-100 X-Y plotter has a standard Centronics interface built in for easy compatibility with any computer which can already operate a printer, and offers a very large A3 maximum paper size at a very low comparative cost.

The DXY-100 is capable of tabulation in 0.1mm steps, automatic measuring and data processing, simple graphic drawing, music scoring and soon. It includes fourteen control commands including options for solid or broken lines, 10 different marking shapes, 15 letter sizes, axis changeover, and the potential for ROM expansion for complex tabulation including curves, hatchings and original character design. One obvious application is in transcription of music from the Compu-Music unit.

The range of Amdek VDU's includes two monochrome and four colour units. The Video 300 and the Video 300A are black and white monitors with green and amber screens respectively, each with anti-glare design and intended to sit neatly on an Apple, for instance. Like all the monitors they offer much higher resolution than standard television screens, greater picture stability in the case of games, and for the colour monitors better separation between the sixteen tones often available nowadays.

Colour 1 has a standard composite video input with audio channel and built-in speaker, whereas Colour 2 has an industrial grade CRT and retails for around £700 as a result. Colour 3 has a domestic grade CRT and so is somewhat cheaper, whereas the forthcoming Colour 4 is expected to be of an even higher quality.

The links between Amdek's range of music kits as featured in E&MM or Hobby Amdek, and the peripherals now appearing or Compu Amdek, should be a source of great interest in the near future. Approximate retail prices are £350 for Compu-Music, £200 for the ADA convertor, £700 for the X-Y plotter, and £100 for Video 300/A.

Further details are available from Roland UK, (Contact Details).