Atari 400 Technical Reference Manual page 39

Dis p I a V Ha n dIe
1" (
S: )
The display device is a read/write device with a handler
that supports the following CIa functions:
OPEN
CLOSE
GET CHARACTERS
GET RECORD
PUT CHARACTERS
PUT RECORD
GET STATUS <null function)
DRAW
FILL
The Display Handler can produce the following error statuses:
$84 Invalid special command.
$80 Cursor out-of-range.
$91 Screen mode> 11.
$93 Not enough memory for screen mode selected.
The Display Handler is one of the resident handlers, and
therefore has a set of device vectors starting at location E410.
Screen Modes
You can operate the display screen in any of 20
configurations <modes 1 through 8, with or without split
screen; plus mode
0,
and modes
9
through 11 without split
screen>. Mode
0
is the text displaying mode. Modes 1 through
11 are all graphics modes <although modes 2 and 3 do display a
sub set of th e ATASC I I c harac tel" set>. Mod es
9
thr oug h 11
re~uire
a GTIA chip to be installed in place of the standard
CTIA chip.
TEXT MODE 0
In text mode 0 the screen is comprised of 24 lines of 40
characters per line. Program alterable left and right margins
limit the display area. They default to
2
and 39 <of a possible 0
and 39).
OPERATING SYSTEM C016555 -- Section 5
54