【单选题】
7在DIP40封装的8×51芯片里，接地引脚与电源引脚的引脚编号是什么？___
A. 1、21
B. 11.31
C. 20、40
D. 19、39
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相关试题
【单选题】
9在12MHz始终脉冲的8051系统里，一个机器周期有多长？___
A. 1µs
B. 12µs
C. 1ms
D. 12ms
【单选题】
12下列哪个寄存器是8×51内的16位寄存器？___
【单选题】
14在8×51的输入/输出端口里，哪个输入/输出端口执行在输出功能时没有内部上拉电阻？___
【单选题】
8×51的P0采用哪种电路结构？___
A. 集电极开路式输出
B. 基极开路式输出
C. 发射机开路式输出
D. 图腾柱输出
【单选题】
17在8×51里，若要扩展外部存储器时，数据总线连接哪个输入/输出端口？___
【单选题】
点亮一般的LED所耗用的电流约为多少？___
A. 1~5µA
B. 10~20µA
C. 1~5mA
D. 10~20mA
【单选题】
19一般地，蜂鸣器属于哪种负载？___
A. 电阻性负载
B. 电感性负载
C. 电容性负载
D. 不导电负载
【单选题】
7405/7406的输出采用哪种电路结构？___
A. 集电极开路式输出
B. 基极开路式输出
C. 发射机开路式输出
D. 图腾柱输出
【单选题】
21在继电器中，NO接点是一种什么接点？___
A. 不使用接点
B. 不存在接点
C. 激磁后即开路的接点
D. 常开接点
【单选题】
22所谓2P的继电器，代表什么意思？___
A. 只有2个接点
B. 两相的负载
C. 两组电源
D. 2组c接点
【单选题】
23共阳极七段数码管显示器的驱动信号有何特色？___
A. 低电平点亮
B. 低电平不亮
C. 高电平点亮
D. 以上皆非
【单选题】
24在8×51的程序里，若要将某个输入/输出端口设置成输入功能，应如何处理？___
A. 先输出高电平到该输入/输出端口
B. 先输出低电平到该输入/输出端口
C. 先读取该输入/输出端口的状态
D. 先保存该输入/输出端口的状态
【单选题】
8×51提供几个外部中断和定时器/计数器中断？___
A. 2,2
B. 3,6
C. 2,3
D. 3,7
【单选题】
8×51的IP缓存器的功能如何？___
A. 设置中断优先级
B. 启动中断功能
C. 设置中断触发信号
D. 定义CPU的网址
【单选题】
28若要让采用低电平触发，则应如何设置？___
A. EX0=0
B. EX0=1
C. IT0=0
D. IT0=1
【单选题】
29在Keil µVision3里进行调试/仿真时，在哪里操作才能触动程序中断？___
A. 在Interrupt System
B. 在Cotorl Box对话框里
C. 直接单击魔术棒按钮即可
D. 直接按0键
【单选题】
30在8×51所提供的中断功能里，下列哪个优先级比较高？___
A. T1
B. RI/TI
C. T0
D. INT0
【单选题】
31在TCON缓存里，IE1的功能是什么？___
A. 触发 IE1中断
B. 指示IE1中断的标志
C. 提高IE1优先等级
D. 取消IE1中断
【单选题】
32在Keil C里，中断子程序与函数又何不同？___
A. 中断子程序不必声明
B. 函数不必声明
C. 中断子程序必须有形式参数
D. 中断子程序一定会有返回值
【单选题】
33若要同时启用INT0及INT1中断功能，则应如何设置？___
A. TCON=0×81
B. IE=0×85
C. IP=0×83
D. IE=0×03
【单选题】
35在8×51的Timer里，若使用Mode 0，其最大计数值为多少个机器周期？___
A. 65636
B. 8192
C. 1024
D. 256
【单选题】
36在12MHz的8×51系统里，哪一种方式一次可定时5ms？___
A. Mode 0及Mode 1
B. Mode 1及Mode 2
C. Mode 2及Mode 3
D. Mode3及Mode 1
【单选题】
37若要让Timer作为外部计数只用，应如何设置？___
A. Gate=0
B. Gate=1
C. C/=0
D. C/=1
【单选题】
39下列哪个不是8×51所提供的省电方式？___
A. PD方式
B. IDL方式
C. LP方式
D. 待机方式
【单选题】
89S51的看门狗有何作用？___
A. 重复执行程序
B. 找回遗失数据
C. 复位系统
D. 防止中毒
【单选题】
41若要启用WDT，则应依次填入WDTRST寄存器哪些数据？___
A. 0xe1、0xe2
B. 0xe1、0x1e
C. 0x1e、0xe1
D. 0x10、0x01
【单选题】
8×51的定时器，在下列哪种方式下具有自动加载功能？___
A. Mode0
B. Mode1
C. Mode2
D. Mode3
【单选题】
45下列哪种AD转换器的转换速度比较快？___
A. 双斜率型AD转换器
B. 比较型AD转换器
C. 连续计数式AD转换器
D. 逐渐接近式AD转换器
【单选题】
46下列哪种AD转换器的精密度比较高？___
A. 双斜率型AD转换器
B. 比较型AD转换器
C. 连续计数式AD转换器
D. 逐步逼近式AD转换器
【单选题】
47对于8×8 LED点阵而言，其中的LED个数及引脚各为多少？___
A. 64、16
B. 16、16
C. 64、12
D. 32、12
【单选题】
48在共阳极型8×8 LED点阵里，其阳极如何连接？___
A. 各行阳极连接到行引脚
B. 各列阳极连接到列引脚
C. 各行阳极连接到列引脚
D. 各列阳极连接到行引脚
【单选题】
49在共阳极型8×8 LED点阵里，其阴极如何连接？___
A. 各行阴极连接到行引脚
B. 各列阴极连接到列引脚
C. 各行阴极连接到列引脚
D. 各列阴极连接到行引脚
【单选题】
50双色8×8 LED点阵的列引脚与行引脚各位多少？___
A. 12、12
B. 8、16
C. 16、8
D. 24、8
【单选题】
___的方向规定由高电位点指向低电位点。
【单选题】
三相电动势到达最大的顺序是不同的，这种达到最大值的先后次序，称三相电源的相序，相序为U-V-W-U，称为___。
【单选题】
电路的作用是实现能量的传输和转换、信号的___和处理。
【单选题】
电阻器反映导体对电流起阻碍作用的大小，简称___。
A. 电动势
B. 功率
C. 电阻率
D. 电阻
【单选题】
___反映了在不含电源的一段电路中，电流与这段电路两端的电压及电阻的关系。
A. 欧姆定律
B. 楞次定律
C. 部分电路欧姆定律
D. 全欧姆定律
【单选题】
并联电路中的总电流等于各电阻中的___。
A. 倒数之和
B. 相等
C. 电流之和
D. 分配的电流与各电阻值成正比
【单选题】
串联电路中流过每个电阻的电流都___。
A. 电流之和
B. 相等
C. 等于各电阻流过的电流之和
D. 分配的电流与各电阻值成正比
推荐试题
【单选题】
- I was worried about my maths, but Mr. Brown gave me an A.___
A. Don't worry about it.
B. Congratulations! That's a difficult course.
C. Mr. Brown is very good.
D. Good luck to you！
【单选题】
-Would you go to the concert with me?___, but I'm very busy now.
A. I'd like to
B. Sure
C. No problem
D. Certainly
【单选题】
-I'll be away on a business trip. Would you mind looking at my cat?Not at all. _______.
A. I have no time
B. I'd rather not
C. You can leave
D. I'd be happy to
【单选题】
- Hi, Jim! Nice to meet you.____.
A. Certainly
B. Many thanks
C. OK
D. Nice to meet you, too
【单选题】
- Hello, may I speak to Mike?_____
A. Who are you?
B. Sorry, he isn't in.
C. Thank you very much.
D. Yes, here you are.
【单选题】
- Will you join us for lunch?____.
A. No, I won't
B. Yes, with pleasure
C. Yes, please
D. Yes, help yourself
【单选题】
- Thank you for your great dinner. I really enjoyed it._____you enjoyed it.
A. I'm so glad
B. I'm sorry
C. What a pity
D. Surprisingly
【单选题】
- I heard Susan surprised her teacher by working hard. Yes, ___
A. her teacher worked hard.
B. Susan worked hard.
C. the teacher was surprising.
D. Susan was surprised.
【单选题】
- Peter, don't step on the grass_______.
A. It doesn't matter
B. I can't do it
C. Don't worry
D. Sorry, I won't do it again
【单选题】
- How was your journey to Paris? - ____
A. It went very well.
B. I flew there.
C. I love Paris.
D. Thank you for asking.
【单选题】
- I'm sorry for being late, Mr Lt______.
A. All right
B. That's right
C. Not at all
D. Never mind
【单选题】
- Happy birthday to you! ___!
A. Happy birthday to you
B. I'm very glad
C. That's all right
D. Thank you
【单选题】
- Do you like country music?___.
A. Yes, I like basketball a lot
B. It's far too crowded
C. Yes, I'm crazy about it
D. Oh, it's funny
【单选题】
- Have a cup of tea, ____? Thanks a lot.
A. don't you
B. haven't you
C. shall we
D. will you
【单选题】
- Thank God．It's Friday again．A nice weekend!___.
A. Me too
B. Yes，I'll be free then
C. That's all right
D. The same to you
【单选题】
— Write to me when you get home. OK, I ______.
A. must
B. should
C. will
D. can
【单选题】
Tom is so talkative. I’m sure you'll soon get tired ___ him.
A. of
B. with
C. at
D. on
【单选题】
I don't know ____ to deal with such matter.
A. what
B. how
C. which
D. /
【单选题】
___ is your girl friend like? She is very kind and good-looking.
A. How
B. What
C. Which
D. Who
【单选题】
He ___ driving me home, even though I told him I lived nearby.
A. insisted on
B. insisted at
C. insisted that
D. insisted in
【单选题】
We came finally ___the conclusion that she has been telling lies all the time.
A. of
B. into
C. to
D. at
【单选题】
I won’t make the___mistake next time.
A. like
B. same
C. near
D. similar
【单选题】
He ___lives in the house where he was born.
A. already
B. yet
C. still
D. ever
【单选题】
I am not used to speaking ___ public.
【单选题】
I didn’t know what to do, but then an idea suddenly ___to me.
A. appeared
B. happened
C. occurred
D. emerged
【单选题】
Measles （麻疹） ___ a long time to get over.
A. spend
B. spends
C. take
D. takes
【单选题】
A pair of spectacles ___ what I need at the moment.
A. is
B. are
C. has
D. have
【单选题】
— Five days ___ too long for me to wait.
A. was
B. were
C. is
D. are
【单选题】
You had better ___ a doctor as soon as possible.
A. seeing
B. saw
C. see
D. seen
【单选题】
The boy is not happy at the new school. He has ___ friends there.
A. few
B. a few
C. little
D. a little
【单选题】
I fell and hurt myself while I ___ basketball yesterday.
A. was playing
B. am playing
C. play
D. played
【单选题】
Tom ___ more than twenty pounds on the novel.
A. spent
B. paid
C. cost
D. took
【单选题】
Don't forget ____ the window before leaving the room.
A. to have closed
B. to close
C. having closed
D. closing
【单选题】
Twenty people were___ wounded in the air crash.
A. quickly
B. wrongly
C. bitterly
D. seriously
【单选题】
The top of the Great Wall is ___ for five horses to go side by side.
A. wide
B. so wide
C. wide enough
D. enough wide
【单选题】
We’ve missed the last bus. I'm afraid we have no ___but to take a taxi.
A. way
B. choice
C. possibility
D. selection
【单选题】
Nancy is considered to be ____ the other students in her class.
A. less intelligent
B. the most intelligent
C. intelligent as well
D. as intelligent as
【单选题】
It's _____ that he was wrong.
A. clearly
B. clarity
C. clear
D. clearing
【单选题】
There ____ a book and some magazines on the desk.
A. is
B. be
C. have
D. has
【单选题】
She is not only my classmate _____ also my good friend.
A. or
B. but
C. and
D. too
