ADR	HEXADR	NAME	Description	shadow	OS
53275	$D01B	PRIOR	Priority Selection Register	GPRIOR	all

Priority Settings#

Bit	Value	Description
0	1	P0-P1-P2-P3 PF0-PF1-PF2-PF3 BAK
1	2	P0-P1 PF0-PF1-PF2-PF3 P2-P3 BAK
2	4	PF0-PF1-PF2-PF3 P0-P1-P2-P3 BAK
3	8	PF0-PF1 P0-P1-P2-P3 PF2-PF3 BAK
4	16	Four Missiles add up to be 5th player
5	32	Overlapping Players have 3rd color
6	64	GTIA Mode see next table
7	128	GTIA Mode see next table

P0-P3 Players PCOLR0.../COLPM0...
PF0-PF3 Playfield colors COLOR0.../COLPF0...
BAK background or border color COLOR4/COLBK

A logical OR is done to the colors of players 0/1 and 2/3 when they overlap. Only the 0/1, 2/3 combinations are allowed; you will not get a third color when players 1 and 3 overlap, the priorities set with bits 0…3 are applied.

If put together into a 5th player (set Bit 4 to '1') the missiles get the color of register 3 COLOR3. They still move independently, e.g. set their horizontal positions with HPOSM0 - HPOSM3

GTIA Modes#

This register can be used to select one of GTIA GRAPHICS modes 9, 10 and 11.

GTIA Mode*	Bit 6	Bit 7	Description
9	0	1	16 different luminances of the same hue (color)
10	1	0	9 different colors
11	1	1	16 different hues (colors) of the same luminance

* the same as GRAPHICS x in BASIC

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see also: Player Missile Topics

previous: COLBK

next: VDELAY