L: Tone Envelope
An integer value in the range 0…15
default if omitted : 0
The value used specifies a pre-defined envelope. To define an envelope use the ENT command, A
permanent definition is tone <envelope number> 0, this cannot be changed by the ENT command
and is set to the ‘tone period’ constantly.
M: Noise Period
An integer value in the range 0…15
default if omitted : 0
Specifies the noise to add to the SOUND. If default or zero is used, then no noise is added. Remember
that only one noise period can be set at one time. This means that all channels specified for noise will
receive the same noise.
6.11 The ENV command and volume envelopes
Attack and decay are required to add dimension to the note and give it life. This command (ENvelope
Volume) enables the shape of a note to be formed. It is a good idea before attempting to describe the
shape to the computer using the numeric instruction sequence to sketch out your requirement on
paper. See example below :
Figure 3: Volume envelope example
The shape must be plotted in numbers so that it can be formatted into a command statement. To do
this , subdivide the shape into sections , you may have up to 5. But in each section the shape must be
a straight line. Now divide each section into steps, the number of steps you choose will be known as
the <step count>, these steps will be given a length of time called <pause time>. 1 = l/l00th sec.].
The steps will also have an increase or decrease in volume known as the step size. If no steps are
specified in a section then there is just a volume setting carried forward to the next section.
N.B. When attempting to simulate a musical instrument it is often the case that the initial and final
volume of each note will be zero, so the initial volume setting in the SOUND command should be
zero and all the volume be added by the envelope.
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