Abstract: An interface system for controlling data transmission from a first information processing unit to a second information processing unit includes a handshaking type data transmission path. The handshaking type data transmission path includes a first interface circuit and a second interface circuit. A transmission signal output from the first information processing unit passes the first interface circuit, is then waveform-shaped by the second interface circuit and applied to the second information processing unit. A transmission acknowledging signal output from the second information processing unit passes the first interface circuit and is applied to the first information processing unit. Thus, the timing skews of the signals in the data transmission paths between the first and second information processing units can autonomously be adjusted, thereby preventing further transmission of a transmission signal.

Abstract: A first-in first-out type memory is used as a buffer for data transfer between asynchronous systems. This buffer memory has a minimum delay elastic buffer function in which the number of data storage stages is changed according to the data transfer situation in an output portion of the memory. The data storage memory includes a folded type data transmission path with a going path and a returning path respectively provided with data storage devices of the same number, bypassing paths for coupling corresponding data storage devices in the going path and the returning path, and a valid data detector provided corresponding to each of the bypassing paths for detecting the presence or absence of valid data in a data storage device closer to an input/output portion than a corresponding bypassing path and making the bypassing path enabled or disabled according to the result of the detection.