| 摘要 |
In a digital network system, such as ISDN (Integrated Service Digital Network) system, a data link is established between transmit-side and receive-side stations so that a data transfer is performed onto a public telephone line in accordance with a predetermined protocol. The transmit-side station compresses data read from a storage medium and then transfers compressed data to the receive-side station, while the receive-side station expands the compressed data and then writes it into a storage medium. Before transferring the compressed data, the transmit-side station transmits a data transfer request to the receive-side station, so that if the receive-side station is now ready to receive the compressed data, the transmit-side station transfers the compressed data to the receive-side station. On the other hand, when completing a data transfer, the transmit-side station transmits an end request of data transfer to the receive-side station, so that if the receive-side station is now in a state to respond to a data transfer completion, the data link formed between the transmit-side and receive-side stations is terminated. Herein, the whole storage area of the storage medium is divided into plural storage blocks, so that the data transfer is performed with respect to each storage block. Preferably, the storage medium is a floppy disk, so that each storage block corresponds to each track formed on the floppy disk.
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