| 摘要 |
An improved modem is described which can selectably operate in a synchronous communications mode, an asynchronous data mode, and an asynchronous command mode. A processor (47) controls the operation of the modem, adds starting and ending flags and frame check sequences to transmitted data, searches for flags and sync characters in received data, adds and deletes start, stop and parity bits required for communications with the asynchronous communications element (18), and performs zero bit insertion and deletion for HDLC/SDLC communications. Processor (47) also controls and monitors the operating parameters of the modem engine (60). |
