| 摘要 |
Apparatus for interfacing with X21 equipment is a microprocessor based device. The apparatus has a microprocessor (10) with associated memory (11, 12) which can be coupled to an X21 link by input/output devices (15, 16). The device (15) is a serial input/output device which is employed to operate bit/byte synchronous portions of the X21 protocol and the device (16) is a parallel input/output device which is arranged to carry out steady state functions. The apparatus can function as a tester for X21 equipment and may function as a DTE, a DCE or an exchange simulator between two DTES; alternatively it may function as an adaptor to allow non-X21 equipment such as a V24 terminal (141) to communicate with X21 equipment. |
