by Atoo
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By: Atoo
Category: C64 - C64 Demo - Music
Released on:1989
Remarks:To start the program type in after loading: Sys12288. GBK-test uses a real time Karplus-Strong algorithm that I learned about in high school to make the distorted guitar sounds: - A starting waveform is constructed by copying a portion of ROM. - An NMI is used to play samples at ca 8 Khz (as far as I can remember) - A sample is picked, gets added to the previously used sample and LSR'ed. Then this new sample replaces itself. This morphs the waveform to sound like a string getting plucked. - The sample then gets LSR'ed 2 times (as far as I remember) and then the low nybble is sent to the main volume register. Since I only LSR 2 times (as opposed to 4) there will now be digital distortion of the sound played. - The pitch of the sound is adjusted through the length of the waveform. This method limits the frequency precision when you play higher notes. That's the reason that some notes are slightly out of tune. Sorry about that... /ATOO
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Credits: Code
Added: December 6th, 2023
Added by:Baracuda

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