问题 问答题 简答题

分时系统和实时系统的主要区别?

答案

参考答案:

分时系统是指在一个系统中多个用户分时地使用同一台计算机;实时系统是指计算机及时响应外部事件地请求并在规定时限那完成对该事件地处理,控制所有实时设和实时任务协调一致地运行。

实时系统和分时系统的主要区别有两点:

(1)分时系统的目标是提供一种通用性很强的系统,有较强的交互能力;而实时系统则大都是具有特殊用途的专用系统,交互能力略差。

(2)分时系统对响应时间虽有要求,但一般来说,响应时间由人所能承受的等待时间来确定;而实时系统对响应时间要求很高,一般由控制系统或信息处理磁头所能接受的延迟时间来决定。

填空题
阅读理解

Every year, there is an important lottery( * * )in Newtown. The lottery raises money for the local hospital. Most people buy at least one ticket, because the first prize is a million dollars!

One year, John Smith won the first prize. He immediately gave up his job and started to enjoy himself. He bought the fastest and most expensive car he could find. He bought a motorboat. He traveled twice around the world, eating and drinking at the most expensive restaurants. He went on a safari in Africa. He explored the South Pole. He lived a life of pleasure, luxury and adventure. He put on a lot of weight from eating too much good food.

Two years later, after he had spent all his money, he returned home and asked for his job back. He had only been back at work a few days when one of the girls in the office tried to sell him a lottery ticket.

“You must buy one, John,” she said. “Remember how lucky you were last time?”

“I am not buying any more lottery tickets. ” He said.

“But you must,” the girl argued. “You might win again. ”

“That’s what frightens me,” John said. “If I try to do again all the things I did last year, I will be dead before the end of this year!”

61. Where did the lottery take place?    

A. In the local hospital.    B. In Newtown.   C. In Africa.  D. At the South Pole

62. What was the money raised by the lottery used for?   

A. To buy fast cars.             B. To allow people to travel

C. To help the local hospital.       D. To feed hungry people.

63. What did John Smith win?     

A. A lottery ticket.     B. A car      C. Money      D. A vacation

64. When John Smith won, what was the first thing he did? 

A. He ate a lot.                 B. He bought a motorboat.

C. He bought another ticket.       D. He stopped working.

65. How long did it take John Smith to spend his money?   

A. Two years     B. One year.     C. A few days    D. Until the end of the year.