RPG demo source code

Entry posted by Guest March 5, 2006

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Here's a little demo of an RPG kernel on the Supercharger. It includes source, so you can see how to set things up for a 6K game. Note that I did not bother putting in correct checksums, so Stella will probably squawk.Note that this kernel has some considerable room for improvement. Some comments:-1- This kernel does three playfield stores per scan line. Using reflected playfield mode, and using separate playfield data for even and odd frames, this could be reduced to two. This would also eliminate the need for the Ball, and allow the border to be flicker-free.-2- Alternatively, eliminating one of the playfield stores might free up enough time to show six sprites per line instead of five, thus increasing the number of displayed characters from ten to twelve.-3- In a different version of this kernel I'm developing for 4A50 banking, sprites are shifted by 8 pixels on alternate scan lines (in "flicker-blinds" style similar to Basic Programming, Stellar Track, or Dark Mage). The code for that version ends up taking twice as much RAM as this one (each scan line pair takes just over 128 bytes instead of just under, so I can't fit two in a page) so it probably wouldn't be practical for use on a SuperCharger. If a blank line between character rows were acceptable, however, the resulting code simplification would allow things to shrink back to something almost reasonable.One caveat with flicker blinds: this demo takes advantage of the fact that a shape which is drawn using only even scan lines is a different color from one drawn using only odds. That's fine here--things flicker the same regardless of what scan lines are used. When using flicker blinds, however, shapes that use only even scan lines or only odd scan lines will flicker quite noticeably.This code is copyright 2006 by John Payson and is provided for informative and illustrative purposes only. Write supercat at casperkitty.com if you wish to use it for any other purpose.

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