[stella] My first demo in a while.

Subject: [stella] My first demo in a while.
From: "Nick Bensema" <nickb@xxxxxx>
Date: Sun, 4 Aug 2002 14:13:53 -0700
I'd like to send everyone an advance copy of the first project I've done for the VCS in many years.  I don't think this has been done before, but who knows; this is a much bigger mailing list than when I participated.
The music routines were programmed from scratch.  Each voice has a different sustain-release method, but they're nothing special.  The tune may be familiar, and though I had to make some compromises, it's still probably closer to the original than the music in Journey Escape.  The scrolltext will reveal my original intent.
The scroll routine is the impressive bit.  It uses an obscene 67 bytes of RAM, 60 of which is frivolously spent on two bitmaps.  I will say in my defense that I did not waste a single bit of the bitmap data; since PF0 only recognizes bits 4-7, I used bits 0-3 to contain PF0 data for the right side of the screen.  The only downside to that is that shifting those bits costs eight cycles per scanline, which could probably only be reduced to six by using an AND, an indexed LDA, and a 16-byte lookup table.  It is essentially a proof of concept, and its high RAM demands are made up for by some clever compression in ROM.
I'd rather have put some more graphics up with the remaining scanlines, which still contain the original "how to draw a playfield" routine.  Some more text, maybe a logo, maybe even some player graphics.  Or at least get the text to wrap properly and get rid of the noise at the top.  Perhaps eventually I will.
Here's the source code and binary file.  It'll be cleaned up a bit before I put it on the website.

Attachment: proj1.asm
Description: Binary data

Attachment: proj1.bin
Description: Binary data

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