Maze003.txt
March 11, 1999
Andrew Schwerin
Maze is my first Atari 2600 demo (Yay!). It is a graphics engine that
can be used to display a scrolling image of a maze. The drawing uses
the playfield registers in reflect mode. The maze can be scrolled in any
direction (horizontal, vertical, or both).
This is release v003 of Maze, which means that it's the first
release that works somewhat, although it still needs improvement.
This release is public domain, but please give credit if you use
my program code in one of your own projects.
Release v003 consists of the following files:
maze003.txt - this document, overview of this maze release
maze003.asm - commented DASM assembly listing
maze003.bin - 4K binary cart image
maze003.dis - comment-free distella disassembly
maze003.snd - SND file for use of Mac/SC owners.
These files are available at:
http://www.tiac.net/users/schwerin/maze003/
(please contact me, schwerin@xxxxxxxx, if you can't access the files)
Features:
The maze map is one page long (256 bytes) and represents a grid of
32x32 segments (maze walls).
Scrolling is controlled by player0 joystick. Pressing the button
makes it scroll faster.
The horizontal resolution is 32 blocks (using playfield graphics)
The vertical resolution is 192 (scrolling is precise to 1 scanline),
however, most scanline data is repeated over 8 or 56 lines.
Drawing kernal has free time. The possibility exists for sprite
support in the future.
Tested on PC Atari and Supercharger.
NTSC (no PAL yet)
Known Issues:
There is a drawing defect for the top line of the graphics. This may
be due to taking too much time in the precompute and missing the
deadline to start drawing.
The vertical lines sometimes disappear when scrolling. I'm not sure
why. Could be an error in my lookup tables.
Vertical lines in the middle of the screen are sometimes double
width. This has to do with the timing of the playfield register
write. I can try tweaking this timing for next release.
The maze isn't "pure white"; it's light blue. Hmmm. What is a good
value to get white?
This thing would look better if the corners between maze walls
were filled in. Yes.
This thing would look better with a real maze and not the current
diagnostic. Yes.
This thing would be cool with at least one player sprite. I want to
fix the drawing before I try that.
(no PAL yet)
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