An experimental videotex system is designed and implemented for verifying KERTI type videotex standard.
The communication's protocol that is studied and implemented in this paper is for the videotex service using public switched telephone network. After a general discussion on the protocols of physical layer and data link layer, communication control processors are designed and implemented.
For the physical layer protocol, EIA RS-232-C interface is adopted and realized to control modem. Since public switched telephone network causes serious noise problem, error recovery for exception condition must be implemented for error-free information exchange. A sliding window protocol using pipeline technology is implemented in data link layer for enhancing line utilization in the experimental videotex system.
HDLC (High-level Data Link Control) and asynchronous protocols are experimented for investigating the characteristics of data link layer protocols on the basis of experimental results, HDLC-asynchronous mixed data link protocol is proposed.
