《计算机组成及汇编语言原理》阅读笔记：p178-p199

《计算机组成及汇编语言原理》学习第 14 天，p178-p199 总结，总计 22 页。

一、技术总结

1.关于 end 的一点疑问

p178, For example, one instruction (BSWAP) swaps the end bytes in a 32-bit register (specified as an argument), a task that could be performed using basic arithmetic in a dozen or so steps.

BSWAP 的意思是 "Byte SWAP", 作用是“The bswap instruction reverse the byte order of the destination. This instruction is provided for converting little-endian values to big-endian format and vice versa.”。

示例：

bswap eax

假设 EAX 寄存器里面的值是 0x12345678, 执行 bswap eax 指令后eax 寄存器里面的值变为 0x78563412。

不是很理解作者为什么加一个 end 去修饰 bytes——"swaps the end bytes"，加了感觉不好理解。

2.superscalar architecture

superscalar: A method of achieving MIMD parallelism by duplicating pipelines or pipeline stages to enhance performance.

3.Microcontroller

A microcontroller is the kind of computer used for small-scale control operations inside devices that one doesn’t usually think of as being computers.

二、英语总结(生词：3)

1.to a greater/lesser degree/extent

idiom. used to describe the effect or importance of sth. 示例：This new tax affects the middle class and, to a lesseer extent, the rich。

p179, Unlike other computers, most notably those with the Power architecture, and to a lesser extent the JVM, the Pentium does not require that all of its instructions take the same number of bits.

如果在看到上面这个句子之前知道这个习语(idiom)——to a greater/lesser degree/extent，那么其实理解这个句子就很容易。因为自己之前没遇到过，同时习语后面没有用逗号，刚开始很不理解。

2.tamper

vi. to make changes to sth that you should not(擅自改动，蓄意破坏)。

This approach is also very fast, but has a substantial security weakness in that any memory address, including memory in use by the operating system or by other programs running on the machine, is available to be tampered with.

3.thermostat

(1)thermostat: thermo-("temperature") + -stat("device for stabilizing or regulating")

c. a device that controls the temperature of a system automatically(温度自动调节器，恒温器)。

p185，Classic examples of such devices include traffic lights, toasters, thermostats, and elevators, but better, more detailed types are the microcontrollers that are now installed in modern automobiles.

三、其它

chapter 9简评：介绍微控制器(microcontroller)的历史背景、组成、汇编语言的使用，内存组织。这些与当前的编程关系不大，可当做历史阅读。

四、参考资料

1. 编程

(1) Patrick Juola，《计算机组成及汇编语言原理》：https://book.douban.com/subject/3069889/

2. 英语

(1) Etymology Dictionary：https://www.etymonline.com

(2) Cambridge Dictionary：https://dictionary.cambridge.org

欢迎搜索及关注：编程人(a_codists)