Atari 800 Basic Reference Manual

GRAPHICS
MODEO
GRAPHICS
MODES
1AND2
This mode is the 1-color, 2-luminance (brightness) default mode for the AT ARI
Personal Computer. It contains a 24 by 40 character screen matrix . The default
margin settings at 2 and 39 allow 38 characters per line. Margins may be chang-
ed by poking LMARGN and RMARGN (82 and 83). See Appendix I. ~orne syst_ems
have different margin default settings . The color ofthe characters IS determmed
by the background color. Only the luminance ofthe characters can be different.
This full-screen display has a blue display area bordered in black (unless the
border is specified to be another color). To displa y characters at a specified loca-
tion, use one of the following two methods .
Method 1.
lineno POSITION aexp1, aexp2
lineno PRINT sexp
Method 2
lineno GR. 0
lineno POKE 752,1
lineno COLOR ASC(sexp)
lineno PLOT aexp1,aexp2
lineno GOTO lineno
Puts cursor at location
sp ecified by aexp1 and aexp2.
Specifies
gr aphics mode .
Suppresses
cur sor.
Specifies character
to be
printed.
Specifies where
to print
character.
Start loop to prevent READY
from being printed . (GOTO
same linerw.J
Press
lll1D:I to terminat e
loop.
GRAPHICS 0 is also used as a clear screen command either in Direct mode or
Deferred mode. It terminates any previously selected graphics mode and
returns the screen to the default mode (GRAPHICS 0).
As defined in Table 9-1, these two 5-color modes are Text modes. Howe v er, they
are both split-screen (see Figure 9-1) modes. Characters printed in Graphics
mod e 1 a re twice the width of thos e printed in Graphics 0, but are the s ame
height. Characters printed in Graphics mode 2 are twice the width and height
of those in Graphics mode 0. In the split-screen mode, a PRINT command is us ed
to display characters in either the text window or the graphic s window . To
print characters in the graphics window, specify device #6 after the PRINT com-
mand.
Example: 100 GR. 1
110 PRINT#6;"
ATARI"
The default c olors de pend on the ty pe of character input. Table 9-2 defines the
default color and color register used for each type.
Table 9-2. Default Colors for Specific Input Types
Character Type
Upper case alphabetical
Lower case alphabetical
Inverse upper case alphabetical
Inverse lower case alphabetical
Numbers
Inverse numbers
Color Register
0
1
2
3
0
2
Note: See SETCOLOR to change character colors.
Default Color
Orange
Light Green
Dark Blue
Red
Or
ange
Dark Blue
46 Graphic Modes and Commands

Atari 800 Specifications

General

Brand	Atari
Model	800
Category	Desktop
Language	English