The official reporter shall perform the duties required of him by law. When not actually engaged in the performance of any other duty imposed on him by this code, he shall render stenographic or clerical assistance, or both, to the judge or judges of the superior court as such judge or judges may direct. In addition to the compensation otherwise provided by law, any reporter required to render such stenographic or clerical assistance shall receive such compensation therefor as the superior court may prescribe, not to exceed the sum of twenty dollars ($20) a day, which shall be payable by the county in the same manner and from the same funds as other salary demands against the county.