Atari ST series Technical Reference Manual page 258

Get Keyboard Input Status
Cconis()
A ll 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 e is a c h a r a c t e r w a i t i n g t o b e r e ­
c e i v e d f r o m t h e c o n s o l e d e v i c e k e y b o a r d .
C macro format
in t s t a t u s ;
s t a t u s = C c o n i s ( );
Machine language format
m o v e . w # $ 0 B , - (s p )
tr 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 c o n i n ( )
250
Cconis
A v a l u e o f 0 m e a n s t h e r e a r e n o c h a r a c t e r s w a i t i n g ,
w h ile - 1 m e a n s t h a t a t l e a s t o n e c h a r a c t e r is w a i t i n g
to b e r e c e i v e d .
Opcode = 11 ($0B)