Code Snippets

This section uses code snippets from existing Bally Arcade games and demos to demonstrate important and/or commonly-used functions. Snippets are typically followed by a short discussion of how and why the listing works as it does.

• The Space Invaders bunker snippet demonstrates how to write a pattern to the screen with WRITP.
• The Space Invaders base snippet demonstrates how to write a pattern to the screen with WRIT.
• The Space Invaders sound effect snippet demonstrates how to play sound using BMUSIC.
• The Star Battle expanded pattern snippet demonstrates how to use the Magic System's Expander option to write patterns.

This section includes code snippets for useful Z80 routines.

• Packed BCD subtraction demonstrates subtracting BCD numbers of varying length.
• Packed BCD addition demonstrates adding BCD numbers of varying length.