Atari 800

HPOSMO- HPOSM3 (Missile Horizontal Position)(MO D004, M1 D005,
M2 D006, M3 D007): These addresses write data into the Missile Horizontal
Position Registers (see HPOSPO description).
D7
D6 D5
D4 D3 D2 D1
DO I
VDELAY (Vertical Delay)(D01C): This address writes data into the
Vertical Delay Register.
D7 D6 D5 D4 D3 D2
D1 DO
P3 P2 P1 PO M3 M2 M1
MO
VDELAY is used to give one-line resolution in the vertical po-
sitioning of an object when the 2-line resolution display is enabled.
Setting a bit in VDELAY to 1 moves the corresponding object down by one
TV line.
If player-missile DMA is enabled then changing the vertical location
of an object by more than one line is accomplished by moving bits around
in the memory map. If DMA is disabled then the vertical location can be
set up by assembly language code which stores data into the graphics
registers at the desired line.
MOPF, M1PF, M2PF, M3PF (Missile to Playfield Collisions)(DOOO, D001,
D002, D003):
These addresses read Missile to Playfield Collisions.
A 1 bit means that a collision has been detected since the last HITCLR.
Not Used
(zero forced) D3
3
D2
2
D1 DO
1 0
Playfield Type
POPF, P1PF, P2PF, P3PF
(Player to Playfield Collisions)(D004,
DOOS, D006, D007): These addresses read Player to Playfield Collisions.
Not Used
(zero forced) D3
3
D2
2
D1
DO
1 0
Playfield Type
MOPL, M1PL, M2PL, M3PL (Missile to Player Collision)(D008, D009,
DOOA, DOOB): These addresses read Missile to Player Collisions.
Not Used
(zero forced) D3
3
D2
2
D1 DO
1 0
Player Number
POPL, P1PL,
P'~L, P3PL (Player to Player Collisions)(DOOC, DOOD, DOOE,
DOOF): These addresses read Player to Player Collisions
Not Used
(zero forced) D3
3
D2
2
D1 DO
1
0
Player Number
(Player 0 against Player 0 is always a zero). Etc.
III.ll