Tone Period Of Step - AMSTRAD cpc 6128 User Instruction
Integrated computer/disc system
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Also See for cpc 6128:
- Service manual (32 pages) ,
- Service manual (31 pages) ,
- Service manual (31 pages)
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Number
of Steps
This parameter specifies how many different steps of tone (pitch) you want the sound
to pass through before it ends. For example, in a note which lasts 10 seconds, you may
wish to have 10 tone steps of 1 second each. In such a case, the <number of steps>
parameter used should be
1 0.
The available range of <number of steps> is 0 to 239.
Tone Period
of Step
Each tone step can vary in the range -
1 28
to
+
1 27
with respect to the previous step.
Negative steps make the pitch of the note higher; positive steps make the pitch ofthe
note lower. The shortest tone period is
0.
This must be remembered when
formulating the tone envelope. The full range oftone periods is shown in the chapter
entitled 'For your reference .... '.
Time per Step
This parameter specifies the time between steps in 0.01 second (hundredths of a
second) units. The range of <time per step> numbers is
0
to
2 5 5,
which means that the
longest time between steps is 2.56 seconds (0 is treated as 256).
Note therefore, that the <number of steps> parameter multiplied hy the <time per step>
parameter shouldn't be greater than the <duration> parameter in the SOU N D
command, otherwise the sound will finish before all the tone steps have been passed
through. (In such a case, the remaining contents of the tone envelope are discarded.)
Likewise, if the <duration> parameter in the SO UN D command is longer than the
<number of steps> multiplied by the <time per step>, the sound will continue after all of
the tone steps have been passed through, and will remain constant at the final tone
pitch.
To experiment with the tone envelope, type in the following program:
HI
ent
1,1111111,2,2
2111
sound
1,142,2111111,15,,1
run
Line 20 specifies a SOU N D with a tone period of 1 42 (international a) lasting for 2
seconds with a start volume of 1 5 (max), without a volume envelope (represented by
a blank parameter, ,) and with tone envelope number 1 .
Line 1 0 is tone envelope number 1 consisting of 1 00 steps, increasing the tone
period (reducing the pitch) by 2, every 0.02 second (2 x 0.01 second).
Foundation Course
Chapter
' 1
Page 73
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