CREDIT DOWN
CREDIT_DOWN ($C00456)
BIOS routine called to deduct credits.
Input: Credits to deduct in BIOS_CREDIT_DEC1 ( $10FDB0) for player 1, and BIOS_CREDIT_DEC2 ( $10FDB1) for player 2.
Input: Credits necessary in BIOS_CREDIT_DEC1 ( $10FDB0) for player 1, and BIOS_CREDIT_DEC2 ( $10FDB1) for player 2.
Credits can be read through $D00034 and $D00035.
Also updates the MVS book keeping.