CREDIT CHECK

CREDIT_CHECK ($C00450)

System ROM routine called to check if there's enough credits for a player.

Input: Credits necessary in BIOS_CREDIT_DEC1 ( $10FDB0) for player 1, and BIOS_CREDIT_DEC2 ( $10FDB1) for player 2. Those locations are set to 0 if there aren't enough credits.

Call CREDIT_DOWN after.

Credits count are located in backup RAM at $D00034 and $D00035. Only the system ROM should use these locations directly.