Entry: VDP Music
by hap, music originally by Jogeir Liljedahl
Format: MSXDOS1, .asm source included
Requires an MSX with analog video cable or RF, preferably connected to a CRT television.
Remember when you were coding MSX Basic on your 1st MSX1 on your bedroom tv? The more text you had on screen, the more buzzing noise your television would make. This especially happened if there was a large difference of contrast between text and background (for example color 15,1,1). The reason this happens is that, more often on older hardware, the analog video signal interferes with the audio signal, causing unwanted noise on the audio line.
This unwanted noise can be manipulated into playing bleeps, or even music. VDP Music is does what its name implies: it lets the MSX VDP play a song. I've made it a few years ago, but never released it to the public, and didn't really intend to. It was made for fun and as proof of concept. This contest sounds like a perfect method to release it anyway. What it does is changing the screen brightness on timed intervals to create a squarewave at different pitches on the video signal. The interference in MSX and/or tv takes care of the rest. Be sure to increase the tv volume.
I've tested it on my MSX2, connected to a 1998 tv to make sure that it works ok.
If you don't have access to the required hardware, meisei (my MSX1 emulator) simulates this effect too (Edit -> Lumi Noise).
Or, just watch this video I made a few years ago: http://www.youtube.com/watch?v=rGA_fVegAb4