Computation and order of service of sentences. (a)  Order of service of sentences.-- If a minimum sentence imposed by the court which is to run concurrently with one which

§ 9761.  Computation and order of service of sentences. (a)  Order of service of sentences.-- If a minimum sentence imposed by the court which is to run concurrently with one which has been previously imposed would expire later than the minimum of such a previously imposed sentence, or if the previously imposed sentence is terminated before the expiration of the minimum sentence of the last imposed sentence, the defendant shall be imprisoned at least until the last imposed minimum sentence has been served. (b)  Sentences imposed by other sovereigns.-- If the defendant is at the time of sentencing subject to imprisonment under the authority of any other sovereign, the court may indicate that imprisonment under such other authority shall satisfy or be credited against both the minimum and maximum time imposed under the court's sentence. If the defendant is released by such other authority before the expiration of the minimum time imposed by the court, he shall be returned to a correctional institution of the Commonwealth to serve the time which remains of the sentence. If the defendant is released after the minimum time has elapsed, he shall be considered for parole on the same basis as a prisoner who has served his minimum time in a correctional institution of the Commonwealth. If the defendant is released after the maximum time imposed under the sentence of imprisonment he shall be deemed to have served his sentence.