MCS-51系列单片机共有四个并行I/O口,分别是Po、P1 P2和P3。其中P口一般作地址线的低八位和数据线使用;P2口 作地址线的高八位使用;P3是一个双功能口,其第二功能是一 些很重要的控制信号,所以P3一般使用其第二功能。这样供用 户使用的IO口就只剩下P口了。另外,这些口没有状态寄 存和命令寄存的功能,因此难以满足复杂的IO操作要求

O接口的作用功能定义 计算机/单片机与外设之间起桥梁作用的 电路或部件接口(interface) 协调两者间的差异

1.绪论 1.1判断下列化合物是否为极性分子? (1)HBr(2)I2 (3)(4)()CH3OH(6)CH3-O-CH3 答:(1),(4),(5),(6)为极性分子;(2),(3)为非极性分子。 1.2写出下列化合物的简单电子结构式

1.指出下列各物质分子式中画线元素的氧化数。 O3, H202,,, OF2, HCHO, I20s, K2PtC16, K2Cr2 K2XeF6, N2Ha, H2NOH, Mn20

1阶的概念 设x→x0时(x),y(x)都是无穷小量。 1)若lim(x)=1,则记0(x)w(x)(x→x)。称之为等价无穷小 i)若m2(x)=0,则记(x)=(x)(x→x)。称o(x)是比v(x)的高阶

recognition by most T cells from recognition by B iction. In most cases, both th maturati vation of ma the involver diversity o CD4\ and CD class I MHC Activat Engagement of TcR by Peptide: MHC Initiates interaction of th n antigenic Signal Transduction tide displayed though the sp

Ⅱ. Listening skills Understanding Times and dates w: Oh, look at the clock It's 5: 15. I'll be late for Jennifer's birthday party! I was supposed to leave at 5 o'clock M: Don't worry! You still have some time. The clock is twenty minutes fast Q What time is it now?

重要的萃取体系 1.重要元素的萃取 Hg:萃取光度法,溴甲酚得420nm,pH3-4.5,选择性很高,只有Ag+ 扰。 Cu:双硫萃取,pH1-4,HCl溶液,可与o,Ni,Mn,Pb,Zn,Cd分离。以Br-,I-掩蔽Hg,Ag,Au

Part I Reading(40%) Every human being, no matter what he is doing, gives off body heat. The usual problem is how to dispose of it. but the designers of the Johnstown Campus of the University o Pittsburgh set themselves the opposite problem how to collect body heat. They have designed a collection system which utilizes not only body heat, but the heat given off by such

The expectation or expected value of a random variable is a single number that tells you a lot about the behavior of the variable. Roughly, the expectation is the average value, where each value is weighted according to the probability that it comes up. Formally, the expected value of a random variable r defined on a sample space s is: (B)=∑R()Pr(o) To appreciate its signficance, suppose S is the set of students in a class, and we select a student uniformly at random. Let r be the selected student's exam score. Then