PROCEDURE MOUSE(VAR M1,M2,M3,M4 : INTEGER);

TYPE REG_PACK = RECORD
                  AX,BX,CX,DX,BP,SI,DI,DS,ES,FLAGS : INTEGER
                END;

VAR REGISTERS : REG_PACK;

BEGIN
  WITH REGISTERS DO
    BEGIN
      AX := M1; BX := M2; CX := M3; DX := M4
    END;
  INTR($51,REGISTERS);
  WITH REGISTERS DO
    BEGIN
      M1 := AX; M2 := BX; M3 := CX; M4 := DX
    END
END;