Atari 400 Basic Reference Manual

9
GRAPHICS MODES
AND COMMANDS
This section describes the Atari BASIC commands and the different graphics
modes ofthe ATARI Personal Computer. Using the se commands, it is possible to
create graphics for game, graphics , and patterns .
The commands to be described in this section are:
GRAPHICS
COLOR
DRAWTO
LOCATE
PLOT
POSITION
PUT / GET
SETCOLOR
XIO
The PUT/GET and XIO commands explained in thi s section are special applica-
tions of the same commands described in Section 5.
GRAPHICS (GR.) Format:
Example:
GRAPHICS aexp
GRAPHICS 2
This command is used to select one of the nine graphics modes. Table 9-1 sum-
marizes the nine mode s and the characteristics of each . The GRAPHICS com-
mand automatically opens the screen , S:(the graphics wi ndo w), as device 116. So
w hen printing text in the text w ind ow , it is not nece ssary to specify the device
code. The aexp mu st be positive, rounded to the nearest integer . Graphics mode
0 is a full -scree n display while modes 1 through 8 are s plit screen displays . To
override the sp lit - screen, add the characters + 16 to the mode numb er (aexp) in
the GRAPHICS command. Adding 32 prevents the graphics comma nd from
cl e aring the scre en .
To return to graphics mode 0 in Dir ect mode, pre ss hiii@l;li@ii or type GR.O
and press l;!jiii;Ui
TABLE 9.1-TABLE OF MODES AND SCREEN FORMATS
SCREEN FORMAT
Vert. Vert. Number
Gr. Mode
Horiz.
(Col)
(Col)
Of RAM
Mode Type
(Rows)
Split Full Colors Required
Screen Screen (Bytes)
0 TEXT 40 24
2
993
1
TEXT
20 20
24
5 513
2
TEXT
20 10
12 5 261
3 GRAPHICS
40
20 24
4 273
4 GRAPHICS
80 40
48
2 537
5 GRAPHICS
80
40
48
4 1017
6 GRAPHICS
160
80
96 2
2025
7 GRAPHICS
160 80
96
4
3945
8
GRAPHICS 320
160
192
1/2
7900
The following paragraphs descr i be the nine graphics modes .
Graph ic Modes and Cm nm an d. s 45

Atari 400 Specifications

General

Manufacturer	Atari
Model	400
Type	Home Computer
Release Year	1979
CPU	MOS Technology 6502
CPU Speed	1.79 MHz
ROM	10 KB
Operating System	Atari OS
Keyboard	Membrane keyboard
RAM	8 KB (expandable to 48 KB)
Graphics	ANTIC and GTIA chips
Sound	4 channels
Display	RF output for connection to TV
Storage	Optional cassette tape drive or floppy disk drive
Ports	Cartridge
Display Resolution	320x192 (16 colors)