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2022-08-26
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INTRODUCTION TO AN INTRODUCTION
Sent in by: Tom Jeffries
2915 Harrison
Oakland, CA 94611
INTRODUCTIONS was one of the
first pieces I wrote for the Commodore
64, so you'll have to excuse some
sloppy programming. It's generally a
pretty straight-forward piece, but
there are a couple of things that
are worth a comment.
First of all, notice the FOR/
NEXT loops in lines 80 and 100. By
gradually changing the filter cut-
off frequency the sound changes like
the 'wah' of a 'wah-wah' guitar. Also
notice in lines 220-270 the changes
in the pulse width for voice 3. In
general, the biggest problem with the
SID chip is getting enough variety,
and changing the filter or waveform
provides variety.
This program uses a short machine
code program located at 49160 to gate
the notes on and off. This machine-
language program is called JEFFIRQ V2.
It is on both sides of LOADSTAR. If
you have a machine-language monitor
you may want to take a look.
I hope you enjoy the music; I
certainly had fun writing it.
>Files Used: INTRODUCTIONS
JEFFIRQ V2
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