The playfield control register.
CTRLPF = $0A
Priority, Reflection, Score Mode, Ball Size
| Name | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0
| |
| $0A | CTRLPF | BSIZE1 | BSIZE0 | PRIORT | SCORE | REFLCT |
Functions
Ball Size
The ball can be stretched to 1, 2, 4, or 8 pixels wide.
BSIZE1 D5 | BSIZE0 D4 | Colour Clocks | Example | ||||||
0 | 0 | 1 | |||||||
0 | 1 | 2 | |||||||
1 | 0 | 4 | |||||||
1 | 1 | 8 | |||||||
As it is a single scanline high, the ball must be turned on/off via ENABL at appropriate scanlines.
Playfield Priority
This bit also affects the ball, as it shares the priority with the playfield.
PRIORT D2 | Effect | ||||||||
0 | Players and missiles in front of playfield and ball | ||||||||
1 | Playfield and ball in front of players and missiles | ||||||||
Score Mode
Allows the playfield colours to have the same colour as the players. Can be useful in a two-player game if scores are drawn using playfield, on left/right of screen; the score will take on the player's colour.
SCORE D1 | Effect | ||||||||
0 | Playfield colour from COLUPF | ||||||||
1 | Playfield left half colour from COLUP0, right half colour from COLUP1 | ||||||||
Notes:
- in score mode the playfield takes not only the colour, but also the priority of player 0 / player 1 on the left and right sides of the screen respectively. This results in player 1 being behind the playfield on the left side of the screen. The ball is behind all the other objects and keeps the colour set in COLUPF.
- if bit D2 (playfield priority) is set in CTRLPF, the score mode is disabled no matter the value of bit D1.
Reflect
Reflects (mirrors) the right-side of the playfield, the order PF2, PF1, PF0
REFLCT D0 | Effect | ||||||||
0 | No mirroring | ||||||||
1 | Mirror right hand side of playfield | ||||||||
Related
see TIA