问答题

对8253定时计数器3个通道进行初始化编程的顺序有没有要求?已知8253中O号、l号、2号计数器及控制寄存器地址分别为340H、342H、344.H、346H,试对8253的3个计数器进行编程,使0号计数器设置为方式l,计数初值为2050H;1号计数器设置为方式2,计数初值为3000H;2号计数器设置为方式3,计数初值为1000H。

A.H、346H,试对8253的3个计数器进行编程,使0号计数器设置为方式l,计数初值为2050H;1号计数器设置为方式2,计数初值为3000H;2号计数器设置为方式3,计数初值为1000H。
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I will never forget what my old headmaster had taught me.Normally when you
are only 15 years of age you do not remember most of the things that are
preached by your teachers.But,this particular story is one such lesson that I
will never forget.Every time I drift off course,I get reminded of this
story.

It was a normal Monday morning at an assembly,and he was addressing the
students on important things in life and about committing ourselves to what was
important to us.This is how the story went: An old man lived in a certain part
of London,and he would wake up every morning and go to the subway.He would take
the train right to Central London,and then sit at the street corner and beg.He
did this every single day for almost 20 years.

His house was filthy,and a horrible smell came out of it.The neighbors could
not stand the smell any longer,so they summoned the police officers to clear the
place.The officers knocked down the door,cleaned the house and found small bags
of money all over the house.When they counted the money,they realized that the
old man was a millionaire.

They waited outside his house in anticipation to share the good news with
him.When he arrived home that evening,the old man was met by one of the officers
who told him that there was no need for him to beg any more as he was now a
millionaire. The old man said nothing at all.He went into his house and locked
the door.The next morning he woke up as usual,went to the subway,got into the
train,and sat at the street corner and continued to beg.Obviously,this old man
had no great plans,dreams or anything significant for his life. We learn nothing
from this story other than staying focused on the things we enjoy doing.

We should remain true to our course,which may mean committing ourselves to
things that people around us would normally disapprove.Let nothing distract us
from being happy;let nothing else determine our fate,but ourselves.What makes us
happy is what matters in the end,not what we acquire.

1. The sentence“I drift off course”might be replaced by.
(A). I do not pass a course at school
(B). I am determined to do something new
(C). I fail to stick to what I have been doing
(D). I come across difficulties in my studies
2. According to the passage,the old man.
(A). lived in Central London
(B). came from a poor family
(C). began begging as a child
(D). begged in London every day
3. When they waited for the old man,the police expected he would be.
(A). pleased to see the clean house
(B). glad to know that he was rich
(C). angry with what they had done
(D). grateful for what they did for him
4. The old man is admired mainly because.
(A). he stuck to what he did
(B). he had a splendid dream
(C). he was confident in himself
(D). he had great plans for the future
5. The old headmaster told the story to remind his students of the
importance of.
(A). honesty 
(B). commitment 
(C). kindness 
(D). patience

A.Normally
B.But,this
C.Every
D.
E.This
F.He
G.He
H.
I.The
J.The
K.When
L.
M.When
N.He
O.The
P.Obviously,this
Q.
R.Let
S.What
T.
U.
(A).
V.
(A).
W.
(A).
X.
(A).
Y.
(A).
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