I'm working up a blog post (or posts) about chiptunes, and decided to do a bit of preliminary research. Though I've been an avid chiptune fan since back when chiptunes were just called 'game music' because the games were brand new, I never actually learned much about how sound production worked on old computers. So I dusted off (metaphorically speaking -- they were in PDF form) the Commodore 64 user's manual and a few issues of Compute's Gazette, to learn a bit more about my favorite chiptune chip, the MOS Technology 6581/8580 Sound Interface Device, better known as the SID. This is the chip that powered the Commodore 64's sound, and therefore powered the epic compositions of artists like Martin Galway, Rob Hubbard, Jeroen Tel, Dave Warhol, and Ben Daglish. That music is the very pulse of my childhood and even in adulthood I still keep finding new things to admire in it.
So the above screenshot is of a little program I wrote on my Commodore 64 emulator, WinVICE, to play a few notes in very rapid succession. The "POKE" commands on lines 40, 70, 90, and 110 tell the computer to play the pitches C, E, G, and C -- a simple C-major chord broken up into an arpeggio. The lines with "FORT=..." determine the length of time each note sounds, and it turns out that "1TO10" is a very short time. Line 130 loops the four notes over and over again. The end result is a very fast, rippling arpeggiation sound -- something that would become essential to the texture of SID tunes, especially those by Galway, and which plays exactly to the strengths of computerized music because of course no human could play the notes that fast, at least not without getting tired pretty quickly. Well, maybe Liszt could.
Anyway, the program in the screenshot above results in this sound.
It was a delight just to make this little foray into an obsolete form of computer audio technology which still, 35 years later, seems like incomprehensible wizardry. I wish that, as a 10-year-old, I had actually read the damn manual for my family's C64 instead of just playing games all the time.
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