数据总线

The system bus is divided into three logical functions; the address bus, the data bus and the control bus .

系统总线的功能在逻辑上被划分为三部分：地址总线、数据总线和控制总线。

In the M51954AFP, when MRD = 1, it enables the three-state bus drivers (DB0-DB3) and transfers data from the DATA-IN lines onto the data bus.

在M51954AFP，当MRD的= 1，它使三态总线驱动程序（DB0 - DB3小波），从数据中的数据总线上传输数据。

Theoretically,system memory bus with a speed of 66 MHz and a 64-bit data bus bandwidth can move 528 megabytes of data per second maximum(66 megacycle/sec*64 bits*1 byte/8 bits=528MB/sec).

在理论上，66MHz 速度的系统存储总线加上64位数据总线带宽，一秒钟内最多可传送528兆字节的数据。

Big-Endian ConfigurationA signed byte load expects data on data bus inputs 31 through to 24 if the supplied address is on aword boundary, on data bus inputs 23 through to 16 if it is a word address plus one byte, and so on.

大尾段配置阿签署字节负载预计在31日的数据总线输入数据，如果通过向24所提供的地址上的字的边界，数据总线投入23日至16如果它是一个字地址加上一个字节，依此类推。

However, it may be avoided quite simply by not connecting the databus directly to the converter but by using a latched buffer as an interface.

不过，只要让转换器通过一个缓冲器连接到数据总线，而不是直接连接数据总线，就可以轻易解决这个问题。

Although Chinese claimed that combat data systems based on MIL-STD-1773 fiber optic databus standard have been already successfully developed by the early 2000s, it is highly unlikely this latest version is adopted for Type 052C, which is most likely still to have MIL-STD-1553B databus standard.

中国人称这种基于MIL-STD-1773光纤数据总线标准制造的作战系统早在2000年早期就已研制成功，但这种与052C型舰使用的最后版本相当不一样，052C型舰最有可能仍然基于MIL-STD- 1553B数据总线标准。

For example, if a register isconnected to the data bus in an 8-bit machine. eachline of the bus connects to register.Because the databus will be an 8一bit bus, there are 8-bit Flip-flopsthat form the register, When there is information onthe data bus,and a particular register is selected toreceive data, all the Flip-flops will store data simultancously. This kind of register is refer is referred to as aparallel register.

例如，如果寄存器被联接到一台8位机的数据总线上，那么，该总线的每一条线均联接到寄存器上，因为数据总线是8位总线，所以有9个触发器来形成寄存器，当在数据总线上有信息，并且选择了一个特定的寄存器来接收数据时，那么所有的触发器将同时存储数据，这种形式的寄存器叫做&并行寄存器&。

Pinout: C High-performance 32-bit RISC Architecture C High-density 16-bit Instruction Set C Leader in MIPS/Watt C Little-endian C Embedded ICE (In-circuit Emulation) 8-, 16- and 32-bit Read and Write Support 256K Bytes of On-chip SRAM C 32-bit Data Bus C Single-clock Cycle Access Fully Programmable External Bus Interface C Maximum External Address Space of 64M Bytes C Up to Eight Chip Selects C Software Programmable 8/16-bit External Data Bus Eight-level Priority, Individually Maskable, Vectored Interrupt Controller C Four External Interrupts, including a High-priority, Low-latency Interrupt Request 32 Programmable I/O Lines Three-channel 16-bit Timer/Counter C Three External Clock Inputs C Two Multi-purpose I/O Pins per Channel Two USARTs C Two Dedicated Peripheral Data Controller Channels per USART Programmable Watchdog Timer Advanced Power-saving Features C CPU and Peripheral Can be Deactivated Individually Fully Static Operation: C 0 Hz to 75 MHz Internal Frequency Range at VDDCORE = 1.8V, 85C 2.7V to 3.6V I/O Operating Range 1.65V to 1.95V Core Operating Range -40C to +85C Temperature Range Available in 100-lead TQFP Package

M5L8253P-5引脚说明： C型高性能32位RISC架构C高密度以MIPS /瓦C小端C十六位指令集C领袖嵌入式冰8 - 16 -位和32位的读写支持256K的片上SRAM的 32位数据总线C单时钟周期存取字节完全可编程的外部总线接口C最大的外部地址空间的64M字节多达8个C芯片选择C软件可编程8位外部数据总线8级优先级，独立可屏蔽，向量中断控制器C四外部中断，其中包括一个高优先级，低延迟中断要求32个可编程I / O口线三通道16位定时器/计数器C三个外部时钟输入C两多用途I / O引脚每通道2个通用同步C两专用外设数据控制器通道每个USART可编程看门狗定时器先进的节能特性 CPU和外设可停用独立全静态工作中：C 0 Hz至75 MHz的频率范围内的VDDCORE = 1.8，85℃2.7V到3.6VI / O的操作1.65V到1.95V范围核心工作电压范围在- 40C至+85 C温度范围内使用的100引脚TQFP封装

The data location includes memory data memorizer and memory map register, which share uniform data and address buses, at the same time occupy independent physical spaces, respectively, both physical and logic addresses separated and independently addressed, respectively, and can multiplex the same logic address.

内存数据存储器和内存映射寄存器共享统一的数据总线和数据地址总线。同时，内存数据存储器和内存映射寄存器各自占有独立的物理空间，物理地址和逻辑地址均分开，各自独立编址，内存数据存储器和内存映射寄存器对同一逻辑地址可以复用。

Uniprocessor designs have built-in bottlenecks.the address and data buses restrict data transfers to a one-at-a-time flow of traffic.the program counter forces instructions to be run in strict sequence.even if improvements in performance are achieved by means of faster processors and more instruction parallelism,operations are still run in strict sequence.however,in a uniprocessor,an increase in processor speed is not the total answer because other factors,such as the system bus and memory,come into play.

单处理器设计有内置的一些瓶颈。地址和数据总线限制数据传输的同时同地址的数据冲突情况。即使是通过更快的处理器和更多的并行指令，当然也包括维护，这些方式来提高的性能，程序的运行仍然被限制在严格的程式规则中。然而，在一个单处理器里，处理器速度的提高时不能完全解决这个问题的，这是因为像系统总线和存储器等其他因素同样在起作用。

Objective: To study the effect of polycythemia on blood oxygen saturation.

裴蕾目的：观察RBC剧增而引起的高粘血症对血氧饱和度的影响。

Based on SIMPLER algorithm in the curvilinear body-fitted coordinates, the calculations were performed for Pr=0.7, Re=10~1000 on non-orthogonal non-staggered grids which are generated by elliptic equation systems.

采用曲线坐标系下压力与速度耦合的SIMPLER算法，数值研究了周期性渐扩渐缩波纹通道内脉动流动与换热情况，流动Re数的范围为10~1000，Pr数为0.7。