嵌入式系统词汇表 4

R  

RAM（随机访问存储器）
Random-Access Memory. A broad classification of memory devices that includes all devices in which individual memory locations may be read or written as required.
随机访问存储器。一个包含了所有每个地址能被按需读写的存储设备的粗略分类。  

RISC（精简指令集计算机）
Reduced Instruction Set Computer. Describes the architecture of a processor family. RISC processors generally feature fixed-length instructions, a load-store memory architecture, and a large number of general-purpose registers and/or register windows. The MIPS processor family is an excellent example. Contrast with CISC.
精简指令集计算机。一个处理器族的描述。RISC处理器一般的特征是固定长度的指令集，一个负载储备存储结构，和大量通用寄存器，及寄存器窗口。MIPS处理器族是极好的例子。相对CISC而言。  

ROM（只读存储器）
Read-Only Memory. A broad classification of memory devices that includes all devices in which the individual memory locations may be read, but not written.
只读存储器。一个包括所的的每个地址只能被读，不能被写的存储器的大概分类。  

ROM emulator（ROM模拟器）
A debugging tool that takes the place of-or emulates-the ROM on your target board. A ROM emulator acts very much like a debug monitor, except that it includes its own serial or network connection to the host.
一种在你的目标板上代替或模拟ROM的调试工具。ROM模拟器动作起来象一个除错监视器，除了它包含自己连到主机上的串口或网络外。  

ROM monitor
See debug monitor.  

RTOS（实时操作系统）
Real-Time Operating System. An operating system designed specifically for use in real-time systems.
实时操作系统。一种被特殊设计来用在实时系统中的操作系统。  

race condition（竞争状态）
A situation in which the outcome of a program may be affected by the exact order in which the instructions are executed. Race conditions are only an issue where interrupts and/or preemption are possible and where critical sections exist.
一种程序运行的结果可能被指令执行的顺序影响的情形。竞争状态仅仅有一种情况下产生，在此处中断或（和）优先抢占是充许的并且有一个临界区存在。  

real-time system（实时系统）
Any computer system, embedded or otherwise, that has deadlines. The following question can be used to distinguish real-time systems from the rest: "Is a late answer as bad, or even worse, than a wrong answer?" In other words, what happens if the computation doesn"t finish in time? If nothing bad happens, it"s not a real-time system. If someone dies or the mission fails, it"s generally considered "hard" real-time, which is meant to imply that the system has "hard" deadlines. Everything in between is "soft" real-time.
任何计算机系统，嵌入的或其他的，有一个死线。以下的问题可经被用来区分实时系统与其他的系统：“是迟到的回答坏，还是一个错误的回答坏？”换句话说，如果计算机没有在指定时间内完成它的工作会发生什么？如果什么也没有发生，它不是一个实时系统。如果一些人死或任务失败，它被认为是“硬”实时系统，意思是系统有一个“硬”死线。介于两者之间的是“软”实时系统。  

Recursive（递归）
Said of software that calls itself. Recursion should generally be avoided in an embedded system, since it frequently requires a large stack.
自己调用自己的程序的说法。递归一般在嵌入式系统中是不充许的，因为它常常占有大量的堆栈空间。  

Reentrant（可再入的）
Said of software that can be executed multiple times simultaneously. A reentrant function can be safely called recursively or from multiple tasks. The key to making code reentrant is to ensure mutual exclusion whenever accessing global variables or shared registers.
可同时多次运行的程序的说法。可再入的函数可以被安全地递归调用或由多任务多次调用。使代码可再入的关键在于确保在访问全局变量或共享寄存器时互斥现象发生。  

Register（寄存器）
A memory location that is part of a processor or an I/O device. In other words, it"s not normal memory. Generally, each bit or set of bits within the register controls some behavior of the larger device.
是处理器或I/O设备一部分的储存器的地址。换句话说，不是标准的储存器。一般地，在寄存器控制每一二进制位或二进制位的集控制大量设备的一些行为。