Atari 800

DLISTL and DLISTH should be changed only during vertical blank or with
DMA disabled. Otherwise, the screen may roll. Bit 7 of NMIEN must be set
in order to receive display list interrupts.
CHBASE (Character Address Base Register)(D409): This address writes
data into the Character Address Base Register. The data specifies the most
significant byte (~SB) of the address of the desired character set (see
section II). Note that the last 1 or 2 bits are assumed to be 0.
40 Character Modes
ID7
\
ID6
IDS~4
jD3
ID2 I
)
*
CHBASE
(1s
ll3]f)ll
110 t9
114
8
I
7
I
6
I
s
4
3
7
l:::J::: I
""""
Base Address Char Name Line Counter
20
Character Modes
!D7
ID6 IDS ID4
-.......r
ID3
ID2
ID1
J *
CHBASE
(1s
114
113
1@1
110
9
ls
I
7
I
6:::S
4 3
:k2
1
X2iJ
Base Address Char Name
Line Counter
OS SHADOW: CHBAS (2F4)
PMBASE (Player-Missile Address Base Register)(D407): This address
writes data into the Player-Missile Address Base Register. The data
specifies the MSB r,f the address of the player and missile DMA data (see
section II).
One Line Resolution
ID7
ID6
IDS ID4
ID3
I
not
used
PMBASE
-
';:1
~s
114
1~112
11c~'"7
6
I
s
I
42::3
I
2
I
1
I
0
]
)
Base Address Player-Missile
Player-Missile Scan
Select
Counters
Two Line Resolution
~D7
ID6
IDS-:84
ID3
ID2
I *
PMBASE
'
Qs
113:::82
110~
}
114
Ill
6 s
I
4
I
3
I
2
I
1
I
0
.........,...
Base Address
Player-Missile Player-Missile Scan
Select
Counter
* Not Used
III. 6