Commodore 64 Music in the real world & other related SID stories

Sunday, November 20, 2005

Hello Dr.T

Just found some more interesting information about Dr.T's Algorithmic Composer for the Commodore 64.

This gives a good insight of what was going on within Dr.T's realms.

I think this review comes from the Keyboard Magazine / October 1986. Text by Ted Greenwald.


Algorithmic Composer

JUST WHEN YOU THOUGHT IT WAS SAFE to ditch your Commodore 64 for one of two sexy new megamonster computers, Dr. T's puts out another program. Not just another program, but one that does things no other program even comes close to. And not just things that aren't available elsewhere, but things that many musicians will find take a fair amount of the drudgery out of creating contemporary electronic music, and add a big dollop of fun. In combination with the updated Keyboard Controlled Sequencer (KCS) for the Commodore 128 - also covered in this report - the Algorithmic Composer delivers a kind of MIDI processing power only hinted at until now. Both packages are extensive enough that we can't explain every detail here, and both were under revision throughout the review period, so you can expect even more features than you read about below. We'll try to hit the high points.

The Algorithmic Composer package, consisting of three separate programs, applies logical operations to your input in order to generate something approaching music. Doubtless some musicians will bristle at the thought of calling upon a computer to write their music, while others will view this software as just what consciously or unconsciously they've been looking for: instant musicianship. Well, check your prejudices at the disk drive door, friends; the world isn't quite so cut-and-dried.

The computer, in this case, just crunches input data while following some basic preprogrammed rules and adding some degree of randomness something we all do, at so me expense of creative energy and spontaneity, while we make music. The rules are set, as they are in any musical instrument from a violin to the most sophisticated turnkey music workstation, the degree of randomness is under some control (which is more than many of us can manage), and ultimately it's up to the user to feed the instrument good information if he or she wishes to avoid mediocre results. That takes Creativity, esthetic discrimination, a knowledge of musical materials, and familiarity with the tools at hand-even in the computer age.


The Phrase program makes up melodies according to parameters you provide. The program uses something like a chord chart actually a scale chart to decide what pitch-classes it can choose from during any given beat. Scale options are quite comprehensive: major; harmonic, melodic, and natural minor; dorian, lydian, mixolydian, and phrygian modes; pentatonic; whole-tone; and four user defined scales. (The latter can be entered in any order and can contain redundancies, giving you more sophisticated kinds of control over certain operations than the program generally offers, should you choose to delve that deep). All scales cover three octaves,so that's the outside range for melodies and melodic intervals. Melody range options are one, two, or three octaves, and melodic interval range is adjustable in semitones.

The program breaks melodies up into a theme and a phrase. A theme, basically, is a motif which serves as the basis for the phrase. You can set a theme length in beats/fractions-of-a-beat. The program then cycles through the theme, transposing it according to the scale chart, in order to compute the phrase. (Phrase length is defined by the length of your initial scale chart) Theme and phrase lengths tend to relate in the following ways: If the theme is the same length as the phrase, you'll get a meandering, through composed melody without much coherence. If the theme issome integral division of the phrase (say, a half, a third, or a quarter as long), you'll get something phrased pretty much like pop music, where a melodic fragment simply transposes with the harmonic changes. If the theme length is some uneven division of the phrase, the melody will be phrased in a coherent, but less obvious, manner. If at any point the scale chart takes the theme out of the defined melodic or intervallic range, the relevant thematic material will be transposed into place on a note-by-note basis, which can lead to some interesting variations within the phrase.

In addition, you can specify an average number of notes per measure, a smallest note value (of which all other note-values will be multiples), and a rest probability (percentage chance that any given quantization value, or multiple there of, will be filled with silence), and you can choose among sets of rules for the handling of consonant scale steps and velocity values. If you come across a melody you like and wish to introduce variations in a controlled fashion (rather than generating a new theme and phrase), there's a scramble function that swaps your choice of pitches, note-values, or durations within a theme.

When you boot up Phrase, the default values give you instant perky diatonic techno-pop lines over standard blues changes. By messing around just a bit, you can make it grind out techno-pop bass lines, lead lines, melodies, or backing patterns. lake it from us: It's a kick. We found that the best way to gain control over the program, however, is to enter values that will cause it to emulate lines from some specific composition that you're familiar with. This gets you directly into fine-tuning the parameters to get what you're looking for, rather than allowing the program to pump out meaningless blatlher until it stumbles onto something interesting. When you know what you're after, it's surprising how close you can come.

Much of the program's output is (predictably) lacking in character, and occasionally it spits a few notes fresh out of left field. But it's all good, solid, editable MIDI data,so you can use a sequencer to take what you like and leave the rest (Algorithmic Composer files can be read by Dr. T's Commodore 64 sequencer) or just hit the button again and generate some different material.


This program is pretty simple, but difficult to evaluate. It takes five lists of user-input values-one each for note-value, duration, MIDI channel, pitch, and velocity and combines them into a single sequence. Here's a simple example to show how it works: Say you enter three values for pitch, Middle C, D, and E, and two values for MIDI channel, 1 and 2. The result will be a sequence six events long (three notes times two channek)-C played on channel 1, D on channel 2, E on 1, C on 2, D on 1, and E on 2. The series loop independently, so after that, the sequence will repeat ad infinitum.

The program holds two sets of series data at a time. Thus it can generate two independent, simultaneous sequences, which
adds contrapuntal possibilities to an already complex and fairly unpredictable process. Applied as an extension of phase-music principles, Series is hard to beat. In more conventional applications, it's hard to fathom.

Preliminary experimentation proved Series great for generating harmonically static background textures, which could conceivably be transposed in a sequencer to fit into conventional harmonic progressions. In all likelihood, though, there's a great deal more lurking in this program's code; it's very good at coming up with musical materials that, while controlled, are not obvious from the input.

Stochastic Algorythm Composer (SAC).

This is the closest the package comes to giving you instant music: All you do is enter a tempo, 16 pitches, four MIDI channels, a set of 16 note-or rest-values for each channel, and a choice of staccato or legato for each channel. The program will happily grind out random lines in four voices 'til the cows come home. Depending on your choices, the results will either be cacophonous or Utra-New-Age, though it's possible to shoot something in between.

There's actually a little more to it, enough to give you some interesting kinds of control over the output. First, you can set a transpose value for each voice. This widens the output's harmonic scope somewhat, since otherwise each voice has the same choice of 16 pitches. A controlled,though fairly static, harmonic scheme can be constructed by paying attention to all possible intervalIic combinations of the pitch entries together with their transpositions. In addition, you can trap a certain length of the resulting music say, four bars to be looped. If you choose to permute that looped portion, it will exchange a couple of pitches and note values every few repetitions. This kind of controlled repetition and variation can give you some pretty coherent output.

Like the other two programs, SAC derives much of its value from the user's sense of discrimination. While it's a trivial matter to arrive at values that produce good sounding results, making music out of them requires, at the very least, careful input selection. The next step is to separate the wheat from the chaff by block editing in a sequencer, and after that to edit the individual lines. The program's tendency toward harmonic stasis, for example, can only be overcome by waiting until it produces something that sounds like a chord change, snipping that section out, and discarding the rest; then it might be desirabie to fix the voiceleading. Nonetheless, for those who are satisfied with the raw results and they can be very pleasant - there's virtually no work involved in obtaining them, and they can be customized somewhat to the uses's tastes.

Given the user's potential role in editing the products of these three programs, you might want to look into a program tailor-made for doing just that: Dr. T,s new version of the Keyboard Controlled Sequencer



  • At Monday, November 21, 2005 8:40:00 pm, Blogger matrix said…

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  • At Saturday, November 26, 2005 3:10:00 pm, Anonymous Anonymous said…

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