Frame transfer device for a fixed format frame transmission network

Claim 1

A frame transfer mechanism for a processor controlled network node connected to network link, wherein fixed length data frames including a fixed number of slots with each slot containing a predetermined number of bits are received as input frames to be transferred and stored into a memory for later transmission within output frames over the network link, said frame transfer mechanism including: a network adaptor (20) including deserializing/serializing means connected to said link for deserializing data received frame slots contents to be transferred to the memory, and serializing the memory provided data to be transmitted onto the link; a storage means connected between said memory and said serializing/deserializing means; said storage means being partitioned into a first section for storing the predetermined number of bits received from the input frames, a second section for storing the predetermined number of bits to be transmitted in the output frames and one extra bit position each for storing a flag bit coupled to the first section and the second section; shifting means having outputs coupled to the storage means and for shifting the bits from the first section and the second section; means (23) for inserting the flab bit into the bit position which is coupled to the second section; means sensitive to a received frame over the link to derive a network synchronization signal therefrom said means being located in the network adapter (20); and synchronization logic means (25) responsive to said flag bit and to said network synchronization signal to derive therefrom an indication signal which indicates normal synchronized transfer mechanism operation whereby the indication signal is used to read the second section.