
                   "Thrust" for the Gameboy Advance
                             by Grumpy Cat

This is Grumpy Cat's tribute to Atari ST "Thrust" for the Gameboy Advance.


ABOUT THE LICENSE
=================
This software is provided AS-IS, free of charge and with no warranty.  It is
not guaranteed to do anything.  It is not guaranteed to do nothing.  The
program binary is not intended for use of any kind, and is not intended to be
loaded onto any computer system, handheld or otherwise and is only provided
to pad out the ZIP file to a respectable size.  Do not get wet.  Do not
feed after midnight.  Do not eat.


ABOUT THE GAME
==============
Grumpy Cat's "Thrust" is based on the Atari ST version of "Thrust"
by Alan Butcher - which is the version I played the most in the 80s.
It includes the following:
    + Complete game: intro, info screens, demos, high score table (and
      the game itself).  All 80s style.
    + All 10 missions from the Atari ST version.
    + High scores saved to battery backed RAM.
    + Antialiased sprites and tether.
    + Reverse gravity.
    + Invisible landscape.
    + All-new sound effects.
    + Original Atari ST "Thrust" theme by Rob Hubbard.

My Gameboy Advance has an Afterburner backlight and the color palette has
been tuned for high contrast and good AA performance on that screen - that's
why the bullet sprites are white instead of red...  red bullets were almost
invisible on my screen.

Jeremy C. Smith wrote the original "Thrust" for the BBC Microcomputer.
I used the status display and font from his version as I think they look
better than the Atari ST version.


ABOUT THE CONTROLS
==================
The in-game info screens give the main controls:
  Left             Rotate ship left (anti-clockwise).
  Right            Rotate ship right (clockwise).
  B                Thrust.
  A                Fire.
  Right Shoulder   Shields / Tractor beam.
  Left Shoulder    Abandon game (without high score entry).
  Start            Pause.


ABOUT THE VERSIONS
==================
Version 1.00 was released on January 5th, 2003.
  First release.

Version 1.01 was released on March 4th, 2003.
  A few cosmetic fixes.  Nothing important.
Version 1.02 HEAVY was released on August 16th, 2003.
  A Heavy Gravity version of 1.01.
Log:
  Made "START" the pause key.
  Clear BIOS interrupt flag and use VBLANK intr instead of spinwait.
  Fix last character in Grumpy intro at wrong pos.
  Fix ball tether centering.
  Fix sound popping.
  Fix dirty linedraw tiles after demo.
  Fix end-of theme tune overrun.
  Added heavy gravity and extra thrust.


ABOUT THE TOOLS
===============
The following tools were used to develop "Thrust":
  STEEM            Atari ST emulator for ST "Thrust".
  BeebEm           BBC Microcomputer emulator for the Original "Thrust".
  Devkit Advance   Gameboy Advance code generation and libraries.
  crt0.s lnkscript Jeff Frohwein's Gameboy Advance linking and startup.
  CYGWIN           X-Window System, GCC for Win32, vi, development environment.
  Tile Studio      Font generation.
  Quack            Synthesized sound effects generation.
  Paint Shop Pro   Graphics editing.
  FlashAdvance II  Flash card and linker software for the Gameboy Advance.


ABOUT THE GAMEBOY ADVANCE
=========================
I read pretty much everything I could find on programming the GBA, but my
two main sources of information were:
  "CowBite Virtual Hardware Specification" by Tom Happ.
  "Audio Programming on the Gameboy Advance" by Chris Strickland.


Grumpy Cat (grumpycatsoftware@yahoo.com)
http://www.geocities.com/grumpycatsoftware.
August 16th 2003.

