Atari ST series Technical Reference Manual page 191

Get Output Device Status
Bcostat()
B c o s t a t ( ) te lls y o u w h e t h e r a p a r t i c u l a r o u t p u t d e v i c e is r e a d y to a c c e p t a
c h a r a c t e r . I t c a n b e u s e d t o a v o i d " h a n g i n g " y o u r p r o g r a m u p b y s e n d i n g
a c h a r a c t e r to o n e o f t h e o u t p u t r o u t i n e s w h e n t h e d e v i c e is n o t r e a d y .
C macro format
in t d e v n u m ;
lo n g s t a t u s ;
s t a t u s = B c o s t a t ( d e v n u m ) ;
Machine language format
m o v e , w # d e v n u m / - ( s p )
m o v e . w # 8 , - ( s p )
t r a p # 1 3
a d d q .l # 4 , s p
Inputs
d e v n u m w o r d
Results
DO s t a t u s l o n g
See also
B c o n o u t ( ) , B c o n i n ( ) , B c o n s t a t ( )
Bcostat
T h e d e v i c e n u m b e r o f t h e i n p u t d e v i c e
w h o s e o u t p u t s t a t u s is t e s t e d :
0 =
1 =
2 =
3 =
5 =
T h e o u t p u t s t a t u s o f t h e d e v i c e :
0 = n o t r e a d y t o r e c e i v e a c h a r a c t e r
- 1 = r e a d y to r e c e i v e a c h a r a c t e r
P R N : ( P r i n t e r p o r t )
A U X : (R S - 2 3 2 p o r t )
C O N : ( C o n s o l e s c r e e n )
M I D I: (M I D I o u t p u t )
I K B D : ( I n t e llig e n t k e y b o a r d c o n ­
tr o ll e r )
Opcode = 8
183