Atari ST series Technical Reference Manual page 203

Get Screen Resolution Mode
Getrez()
G e t r e z ( ) c a n b e u s e d to d e t e r m i n e t h e c u r r e n t d i s p l a y m o d e . T h e t h r e e
d i s p l a y m o d e s c u r r e n t l y s u p p o r t e d b y t h e S T a r e l o - r e s ( 3 2 0 x
c o l o r s ) , m e d i u m - r e s ( 6 4 0 x 2 0 0 , 4 c o l o r s ) a n d h i - r e s ( 6 4 0 x 4 0 0 , b l a c k a n d
w h i t e ) .
C macro format
in t r e z ;
r e z = G e t r e z ( );
Machine language format
m o v e . w # 4 , - ( s p )
t r a p # 1 4
a d d q .l # 2 , s p
Inputs
N o n e
Results
DO r e z w o r d
See also
S e t s c r e e n ( )
Getrez
A f la g t h a t i n d i c a t e s t h e c u r r e n t d i s p l a y r e s o l u t i o n :
0 = L o w r e s o l u t i o n
1 = M e d i u m r e s o l u t i o n
2 = H i g h r e s o l u t i o n
Opcode = 4
2 0 0 , 1 6
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