Atari ST series Technical Reference Manual page 263

Get RS-232 Output Status
Cauxos()
T h is f u n c t i o n a l l o w s y o u t o d e t e r m i n e w h e t h e r t h e R S - 2 3 2 s e r i a l d e v i c e is
r e a d y t o a c c e p t a c h a r a c t e r .
C macro format
in t s t a t u s ;
s t a t u s = C a u x o s ( );
Machine language format
m o v e . w # $ 1 3 , - ( s p )
t r a p # 1
a d d q .l # 2 , s p
Inputs
N o n e
Results
DO s t a t u s l o n g
See also
C a u x o u t ( )
Cauxos
A 0 m e a n s t h e d e v i c e is n o t r e a d y to a c c e p t a c h a r a c ­
t e r , w h i l e a - 1 m e a n s it is r e a d y .
Opcode = 19 ($13)
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