《Operating System Concepts》学习第 6 天，p26-p33 总结，总计 8 页。

一、技术总结

1. timer

(1)为什么设置 timer

We must ensure that the operating system maintains control over the CPU. We cannot allow a user program to get stuck in an infinite loop or to fail to call system services and never return control to the operating system. To accomplish this goal, we can use a timer.

(2)定义

A hardware component that can be set to interrupt the computer after a specifi ed period.

二、英语总结(生词：4)

1.reclaim

(1)reclaim: re-("again") + clamare("cry out, shout, call")

vt. recalim litterally means "to claim back", "to take back", or "to demand the return of sth"。It is often used to describe restoring something to a better state or asserting ownership over something that was lost or taken away.

示例：When the process terminates, the operating system will reclaim any reusable resources(《Operating System Concepts》第 18 页)。

2.rigidly

(1)rigid: rigere("be stiff(firm or hard)")

adj. stiff or fixed; not able to bent or moved.

(2)rigidly

adv. in a stiff or fixed way.

示例：Files may be free-form (for example, text files), or they may be formatted rigidly (for example, fixed fields such as an mp3 music file)(《Operating System Concepts》第 29 页)。

在上面这句话中，rigidly 的意思是“strictly, inflexibly, in a highly structured manner”,当然，这种描述比较抽象。

3.hinge

(1) hinge: hangen("to hang")

c. a piece of metal that fastens the edge of a door(固定门的铰链(注：搜实物图来看))。vi. (+on/upon)depends on。

示例：The entire speed of operation of a computer may hinge on the speeds of the secondary storage subsystem and the algorithms that manipulate that subsystem(《Operating System Concepts》第 30 页)。

4.peculiarity

(1)peculiar: peculium("private property, personal possession")

adj. Peculiar literally means "sth that is specially one's own", like personal propery, over time, peculiar envolves to mean "sth that is distinct, unusual or different"。

(2)peculiarity: peculiar + -ity

c/u. the distinctive, unusual, or unique feature or characteristic of sth(特性).

示例：Only the device driver knows the peculiarities of the specific device to which it is assigned(《Operating System Concepts》第 32 页)。

关于英语的注解同步更新汇总到 https://github.com/codists/English-In-CS-Books 仓库。

三、其它

感觉自己很弱，缺的知识很多，阅读进度很慢。

四、参考资料

1. 编程

(1) Abraham Silberschatz，Peter Baer Galvin，Greg Gagne《Operating System Concepts》：https://book.douban.com/subject/30272539/

2. 英语

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

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

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