Hi all,
The following works well and I found it quite simple.

I agree with Andy Neil that it is not important whether it is 8255 or anything else. It was a matter of accessing specific external data memory locations. Thats why in my original question was: How to access memory mapped 8255 with SDCC?

#include <compiler.h> 
 
SFRX( CONTROL_8255, 0x280b ); 
 
void main() 
{ 
CONTROL_8255 = 0x80; 
} 

 

compiles to:

_main: 
; 8255.c:7: CONTROL_8255 = 0x80; 
mov dptr,#_CONTROL_8255 
mov a,#0x80 
movx @dptr,a 

 

Thanks to all for a good discussion..