RS-232C是(34)之间的接口标准，其规定的电平表示方式为(35)。当使用 RS232C连接相关设备时，电缆的长度不应超过(36)m。当用RS232C直接连接两台计算机时，采用零调制解调器方式，其连接方式为(37)。当计算机需要通过相连的MO- DEM发送数据时，依次设置的信号是(38)。

(78)

(79)

(76)

(77)

(71) is a one -way function that takes an arbitrarily long piece of plaintext and from it computes a fixed-length bit string.

  (72) is a protocol that most USENET machines now use it to allow news articles to propagate from one machine to another over a reliable connection.

  (73) is an approach preferred by cable TV providers. In this solution the fiber terminates at an optoelectrical converter and the final segment is a shared coaxial cable.

  (74) is a device used to connect two separate network that use different communication protocol.

  (75) is a digital-to-digital polar encoding method in which the signal level is always either positive or negative.

(73)

(74)

(71)

(72)

In the following essay, each blank has four choices. Choose the most suitable one from the four choices and write down in the answer sheet.

 Open Shortest Path First(OSPF) is a(66)routing algorithm that(67)work done on the OSI IS-IS intradomain routing protocol. This routing, as compared to distance-vector routing, requires(68)processing power. The Dijkstra algorithm is used to calculate(69)OSPF routing table updates only take place when necessary,(70)at regular intervals.