Product: Opus
Supplier: The Advisory Unit, Endymion Road, Hatfield, Herts AL10 8AU.
Tel: (07072) 65443
Price: £15.00 inc. VAT

In spite of the fact that many pundits are trying to write off the BBC micro it is still very much alive and kicking, especially in the world of education. It has had an enormous number of music programs written for it and Opus is one of the latest.

Although neither the program nor the manual actually say, "this is an educational program", hints to that effect are scattered throughout and Opus seems to have been designed for classroom use. The new music curriculum places much emphasis on composition, a topic which both pupils and teachers often have difficulty in getting to grips with, and it is this subject which Opus tackles.

The disc is not copy-protected and the manual tells you to make a back-up copy before use - a wise precaution and a brave and welcome move on behalf of The Advisory Unit.

Opus lets you construct tunes on a grid using all three of the BBC's sound channels. You control the program by moving a pointer around the screen to point to an option and pressing Return. Control can be with the cursor keys, a joystick, a tracker ball or the Concept Keyboard. I found cursor control to be the best although the program is written in Basic and the pointer steps around the screen rather than gliding. But this is not a severe problem.

Opus has three screens - the Main menu, the Composition screen and the Editing screen. Tunes are built up in the Editing screen. This displays a grid with a list of 22 note names down the left hand side. Initially there are 34 boxes across the screen (the maximum number of notes you can enter on one grid) but this can be reduced to 24. Notes are toggled on and off by pointing to a box and pressing Return. The pointer moves on automatically ready for another note, a nice touch.

You can enter a three-part tune on a single grid (or 'card' as the program calls them) in which case the notes appear at the bottom, centre and top of the box. This works quite well although it's not always easy to tell which notes belong to which channel at a glance.

Unfortunately, you don't hear the notes as you enter them on the card. The manual says you don't need any previous musical experience or a knowledge of music notation in order to use Opus but as you don't hear notes when you select them and as reading notes on a grid is not exactly an instinctive process (although neither is traditional notation, come to that), the novice will probably only be relying a crude sense of 'higher' or 'lower' when entering notes. To this end some sort of supervision would be helpful (back to education again) unless you are happy with a trial and error approach.

To actually hear what you've written you select the Play option - of course. The program compiles the data (taking a second or two to do so) and then you hear the music. The delay between entering notes and hearing the card may be slight but but, given the nature of the display and the note representation, a single 'instant' play button - say a function key - would have been very useful.

Notes placed in adjacent boxes sound as one long note so to repeat the same pitch you must leave an empty box between notes. Although not a severe limitation given the introductory nature of the program this just goes to demonstrate that even alternatives to traditional notation have their own problems.

Some particularly interesting composition options can be found in the Reflect menu. You can reverse the notes so the card effectively plays backwards; you can invert the tune so the high notes play low and vice versa; and you can shift the tune, effectively a transpose function. These can be applied to individual channels or to the whole card.

These are the sort of musical manipulations which are ideally suited to computer control, and they offer much scope for experimentation. Music by Bach in particular lends itself well to such functions. New pieces of music can be constructed which still have a degree of musical coherency with the original card. Experimenting with these operations is fascinating.

You can copy one card to another although a function to copy one channel's note to another would have been useful, too, especially when experimenting with the Reflect options.

Opus has another trick up its sleeve, too. You can alter the Note List which appears down the left of the grid. There are two fixed lists - major and chromatic - and a programmable list. This is originally set to pentatonic (the black notes on a piano) but you can create, save and load your own lists using a separate program on the disc. Files are supplied for whole tone and quarter tone scales.

You can alter the pitch and volume of the notes and select one of six types of envelope. I didn't find the envelope definitions particularly impressive, however - two are very similar and one produces a horrible heavy vibrato. There is no facility to create your own envelopes. On the one hand that's a shame, but on the other it avoids confusing the user with a mass of envelope data; probably a good thing.

You can create up to twelve music cards and link them together in the Composition screen. Again, this is grid based and card numbers are entered in a 10 by 6 grid to form the final tune. You can alter the tempo from the Main menu and this ranges from 2 to 10.

Three music files are supplied on disc - a Bach three-part Invention, In Dulcio Jubilo, and an original composition which makes use of the Reflect functions. Try some of these on the Invention file, too - great fun. A printout can be produced by pressing CTRL-P - very useful for classroom work.

For a program which is so ideally suited to education, it's surprising that the manual doesn't include any suggestions for use in that area. In particular, the Note Lists can be loaded independent to the grid, and users could explore the melodic and harmonic differences produced using the same grids and different notes. There is also scope for experiment in song construction by linking grids together in different orders.

The manual is short - 20 pages - but to the point, and with screen dumps on every other page.

While the program is easy to use and understand, a couple of aspects of its implementation could be tidied up and improved a little, perhaps. But don't let that deter you from investigation as it could certainly give an insight into the role of melodic and harmonic lines in a composition.

While the manual claims you don't need any musical knowledge to use Opus, you do need at least a basic concept of pitch and duration. The solo user could have fun with it, but I reckon it will really come into its own in the classroom under supervision of an enthusiastic teacher where it could form a small part of a course on composition.