Direct transfer from a receive buffer to a host in a token-passing type

Abstract

A data transmission system using media access control of a token-passing type including multiple nodes connected to a common transmission path, wherein each node transmits data in a predetermined period in order in a broadcasting or multicasting manner, and each non-transmitting node receives and stores the data in a receive buffer. Each node includes circuitry for receiving a data frame and detecting whether or not a destination address included in the received data frame is the same as its own destination address, and transmitting a data frame reception end signal when it is determined that its own destination address has been received. A DMA controller extracts predetermined received data included in the received data frame in response to the data frame reception end signal and transmits the predetermined received data to a receive buffer where the predetermined received data are stored. An address conversion memory stores an address of the received data stored in the receive buffer, and converts a specific address externally input to access the received data in the receive buffer into the address of the receive buffer at which the received data is stored, thereby generating a conversion address. A receive and transmission control processing circuit updates the address of the received data stored in the receive buffer, causes the updated address to be stored in the address conversion memory, and accesses the received data in the receive buffer with the conversion address to read out the received data.