CALL INTERRUPT - a statement that allows BASIC programs to perform
                 DOS system calls
Syntax
  CALL INTERRUPT(interruptnum,inregs,outregs)
  CALL INTERRUPTX(interruptnum,inregs,outregs)
    - interruptnum, an integer expression which has a value between
      0 and 255, is a DOS interrupt number
    - inregs contains the register values before the interrupt is performed
      (see Details for how to declare a user-defined type which will
      contain these register values)
    - outregs contains the register values after the interrupt