dos33fsprogs/kfest2018

KFEST18 SUPER RASTERBAR 2K DEMO
	by deater (Vince Weaver) vince@deater.net

Written for the Kansasfest Hackfest.

I started work on this on the morning of Wed Jul 18th and finished
early in the AM on Saturday July 21st.

NOTE: If you run the demo and the sound is scratchy and/or the graphics
corrupted, reboot until it works.  Sometimes the vapor-lock doesn't
happen like it should and I'm not sure why.


How it works:
	The Apple II lo-res mode is usually limited to 40x48 mode.

	However, there are two graphics pages that can be flipped
	between with a soft-switch.

	If you switch between page0 and page1 at just the right time
	(every 2 scan lines) you can create a pseudo 40x96 graphics
	mode, using all 15 lo-res colors.

	Of course there's no VBLANK notification or HSCAN interrupts
	on Apple II.  So you have to read the "floating bus" to find
	out when a scan line begins, and then count cycles to find
	out where to switch things.

	All the calculations for the raster bar, mockingboard sound,
	and scrolling text are done during the 4550 cycles of VBLANK.

	To save space, only two channels of audio are played.


Code by: deater (Vince Weaver)
LZ4 code: qkumba
Music: Muda Kingdom from Super Mario Land (gameboy) by Hirokazu Tanaka
	transcribed from sheet music by G-Han