下面关于8237可编程DMA控制器的叙述中，错误的是A．8237中4个通_爱下问搜题

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问题单项选择题

下面关于8237可编程DMA控制器的叙述中，错误的是

A．8237中4个通道的方式寄存器共用一个端口地址

B．8237每个通道在每次DMA传输后，其当前字节计数器的值可通过编程设置成自动加1或减1

C．8237每个通道有单字节传送方式、数据块传送方式、请求传送方式和级联传输方式

D．8237在固定优先级情况下，DREQ0优先级最高，DPEQ3优先级最低

答案

参考答案：B

解析：本题考查8257工作原理。当前地址寄存器的值在每次DMA传输后自动加 1或减1，为传输下一个字节作好准备，并不需要通过编程设置，所以B是错的。

单项选择题

男性，58岁。2年来出现间歇性无痛性全程肉眼血尿，终末加重，近半年来出现尿频，尿痛，3个月来耻骨后痛，最可能的诊断是（）

A.膀胱炎

B.前列腺增生症

C.膀胱肿瘤

D.膀胱结石

E.肾结核

完形填空

As a young man, Al was a skilled artist, a potter. He had a wife and two fine sons. One night, his oldest son 36 a severe stomachache and died suddenly. To make matters worse, his wife left him a short time la

ter, 37 him alone with his six-year- old younger son. The hurt and pain of the two situations were _ 38 _ Al could handle, and he _ 39 to alcohol. Al began to lose everything he possessed---his home, his land, his art objects, everything. 40 he died alone in a San Francisco motel room.

When I heard of Al’s death, I reacted with the same disdain（蔑视）the world shows for one who ends his life with nothing 41 _ left. “What a complete failure!” I thought. “What a totally 42__ life!”

As time went by, I began to re-evaluate my earlier _ 43 judgment. You see, I knew Al’s now adult son, Ernie. He is one of the kindest, most 44 most loving men I have ever known. I watched Ernie with his children and saw the f

ree 45 of the love between them. I knew that kindness and caring had to come 46 somewhere.

I hadn’t heard Ernie talk much about his father. It is so hard to 47 an alcoholic. One day I get up my 48 to ask him. “I’m really puzzled by something,” I said. “I know your father was basically the only one to 49 you. 50 on earth did he do that you became such a special person?

Ernie sat _ 51 _ and thought for a few moments. Then he said, “From my _52 memories as

a child until I left home at 18, Al came into my room every night, gave me a __53 and said, “I love you, son.”

Tears came to my eyes as I realized what a fool I had been to 54 Al as a failure. He had not left any material possession behind, 55 he left behind one of the finest, most giving men I have ever known.

D．rather than

B．comfortably