int intdosx( union REGS *inregs, union REGS *outregs, struct SREGS *segregs ) - prototype in dos.h - executes 8086 software interrupt INT 21 - copies register values from inregs into the registers - copies segregs->x.ds and segregs->y.es into DS/ES - if CF is set, an error has occurred - unique to DOS - see intdos() int86() int86x() intr() REGS