; Crosstalk/S i/o drivers for SOL-20 computer org 100h jmp 200h org 110h sstat: in 0f8h ; get serial port status ani 1 ; mask input status bit ret ; and return org 120h sin: in 0f8h ; get port status ani 1 ; char. waiting ? jz sin ; no, loop until ready in 0f9h ; get character into acc. ret ; go home with it org 130h sout: push psw ; save char. on stack sout1: in 0f8h ; get port status ani 2 ; mask output status bit jz sout1 ; loop until ready pop psw ; get char. off stack out 0f9h ; send to modem ret ; that's it org 140h ; this code MUST be here ret end