1. A bit oriented digital switch for PCM transmission systems, for controlled change of bit position and PCM word of selected bits and bit groups in PCM words received by said switch, said switch comprising: (a) a first plurality of speech memories for storing the received PCM words, where said plurality is the number of bits in a PCM word, and where each received PCM word is stored once in each of said speech memories; (b) means for controlling selection of one PCM word from each speech memory; (c) a second plurality of word memories, where said second plurality is the number of bits in a PCM word, for storing the selected PCM words; and (d) a third plurality of bit memories; (e) means for controlling selection of one arbitrary bit from each word memory for forming a new PCM word in said bit memories as an output of said bit oriented digital switch.