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Air on a Rasterline

My contribution to the C64 Music compo at Datastorm 2013, where it ended up on 5th place.

The tune is remarkable from a technical point of view, because the playroutine only needs 63 clock cycles (one rasterline) per frame, whereas a normal playroutine needs around 24 rasterlines. To put that in perspective, consider that simply calling the playroutine (jump to subroutine + return from subroutine) uses up 12 cycles, i.e. almost 20% of the available time. Obviously this severely limits the number of features the player can support; there's no vibrato, no arpeggios, and so on. Still, it was fun to try to work musically within those extreme constraints.

This project then went on to inspire Hermit Soft to create One Rasterline Tracker, a tool that lets non-coders take part in the fun. However, his playroutine is not quite down to 63 cycles yet, and believe me, the last few are the hardest. Still, it's a great achievement!

Here's the csdb page for Air on a Rasterline.

Posted Wednesday 20-Mar-2013 17:08

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Wed 10-Apr-2013 01:11
Awesome. Bits of it remind me of the (rather beautiful) tune from Trixie's Trailer in the original Sam and Max PC game :
Fri 12-Apr-2013 08:04
Are playroutines like this similar to loopless algorithms?

For example, loopless algorithms often need to use techniques like focus pointers; it seems to me that a playroutine would need several focus pointers.
Linus Åkesson
Mon 22-Apr-2013 00:58
Are playroutines like this similar to loopless algorithms?

It's an interesting comparison. However, when talking about time complexity one is typically concerned with how the execution time behaves when the size of the problem, expressed as N, grows very large. I don't quite see what N would represent in the context of playing a chiptune. The only property that can be arbitrarily large is the duration of the song (or some dependent property, like the total number of notes). But in that case, as N grows, so does the processing time available for completing the task.