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Soft On Texas

Composer for the TI-99/4A


Paul Coster gets 'plugged in' to a music composition cartridge for the TI-99/4A computer from Texas Instruments.

Despite the fact that most home computers possess extensive built-in 'sound' capabilities — the TI-99/4A from Texas Instruments being no exception — it takes a considerable time to become competent at putting the various commands together to create a melody. What is needed is a range of formalised keywords to take the chore out of writing the same BASIC commands over and over again. And, in essence, that's exactly what the 'Music Maker' cartridge from TI does. Plugging into the slot provided on the machine, the software derived from the cartridge lets you compose music using standard 'written forms' or 'frequency spectrum' approaches.

Notes For The Staff



'Traditional Mode' with the software plays music as a result of notes being placed on a musical staff by the programmer. The initial set-up routine asks for the number of sharps/flats, the time signature (eg, 4/4 gives four crotchet, or single beats, to the bar) and an arbitrary value, from one to 30, of speed. Unfortunately, the software does not allow the first number to be larger than the second (no odd 9/8 times here!), though the permissible time signatures are more than sufficient for a beginner. Another, more favourable point about the command structure (syntax) is that at each stage a default option is available. This means you can start writing something immediately, without having to worry about what the various options will do.

After selecting the initial variables, the screen displays two musical staffs — headed by the bass and treble clefs — and a host of other information. This all relates to aspects of the music you are about to produce. For instance, a number in the top right hand corner tells you which 'measure' (display section) you are working on — number 0001 is the first display. Below this are the notes and rests that can be placed on the staffs, along with symbols for accidentals. Further down come the commands — boxed for clarity — for placing notes, playing tunes and editing etc. In each case the procedure is the same, consisting of placing the cursor over the command you wish to initiate and then moving the graphic — usually a musical note — over to the position on the staff where you want it to play. When a note has been placed, the computer plays it and the length (number of beats) is shown by a line of squares at the base of the screen. These squares also access a volume parameter for each note — a number from one to eight — indicating the loudness of a particular note.

Each time a measure is completed, you have the choice of playing the tune or adding another voice. There are three voices — sets of notes on the staffs — which are colour-coded (or 'color-coded', as Texas puts it) blue, green and red. The three voices can all be played together if desired, or one at a time during song development. Once you are content with a measure you can go on to the next, continuing until a complete song is ready to play.

Compositions may be edited to permit replacing some notes or measures. Additionally, the speed of the song can be changed from that originally specified. Then it's on to the PLAY options. Again, these allow speed changes, but the feature which particularly interested me was the transposition facility. By specifying a number from zero to 11, you can transpose a whole phrase up or down, eliminating the need for doing the job manually — the machine can do it for you!

Graphical Sounds



The other method of creating tunes using the TI Music Maker is via a 'Sound Graph'. This is basically a grid with two axes — notes and frequency (in Hertz). The range of frequencies covered is chosen at the beginning and can be anything from 110Hz up to 40,000Hz (for all you bats out there!) Rather than notes on a staff, the sounds are played as a result of placing lines on the graph. As the lines are moved around, the frequency or 'pitch' is sounded so that you have some idea of what you're playing. This was a useful feature, since it was very easy to set the frequency range to something impractical, so that moving the line around the grid caused the note to move outside the audible range.

The set-up procedures for the Sound Graph mode provide for two sub-modes — continuous and discrete. These merely differentiate between a high or low number of separate frequencies available on the graph (120 or 30 respectively). After deciding whether you want the cursor to move at a snails pace (continuous), or a reasonable speed (discrete), when plotting the lines on the graph, there are further options as with the traditional mode (such as speed). Additionally, in this mode, you have the possibility of using a noise generator for producing special effects. The noises are either periodic or derived from a white noise generator (noise of equal energy across the audio spectrum; 20-20,000Hz). When using the option, you can select a set of 30 frequencies to be played (this does not apply for continuous mode). With both options, the same command procedures exist as for the traditional mode. Volume control is provided via lines placed along the bottom, rather than numbers in squares — the results are the same.

In addition to the three voices, the 'noise' can be added to the other notes and played with the basic tune (though it sounds pretty odd, it's better left as a special effect — a motorbike crashing at the end of the bar?).

Playing About



Both composition modes available from this package provide powerful tools for creating music. The three voice facility means that you are not restricted to a single tune, but that basic chord sequences and combinations can be played. Here it's well worth experimenting, since three single-voice melodies can sound completely different when combined — remember, you don't have to make each voice coincide beat for beat.

The way the notes or lines are put on the staff/graph is perhaps a bit tedious, but Texas do manufacture joystick controls which may make this easier. Certainly it was a chore tapping the 'arrow' keys on the computer, though this was outweighed by the pleasure gained from listening to a tune which has taken a couple of hours to compose.

This was one of those software packages that couldn't be done justice to within the space of an hours playing. There's no doubt, however, that if you've got a TI-99/4A, or are thinking of buying one, then this cartridge is well worth purchasing at the same time.



Previous Article in this issue

Out Of The Blue

Next article in this issue

Micro-Music


Electronic Soundmaker & Computer Music - Copyright: Cover Publications Ltd, Northern & Shell Ltd.

 

Electronic Soundmaker - Sep 1983

Donated & scanned by: Mike Gorman

Review by Paul Coster

Previous article in this issue:

> Out Of The Blue

Next article in this issue:

> Micro-Music


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