这是一本十分经典的书了，也是大一的时候Introduction to Computer System (ICS) 的教材，但当时刚接触计算机，对这本书的很多地方都是一知半解。现在再回过头来重新看一遍这本书，应该会有不同的体会与收获。
Chapter 1 A Tour of Computer Systems
- 从源代码到可执行文件的过程：
- Running throughout the system is a collection of electrical conduits called buses that carry bytes of information back and forth between the components. Buses are typically designed to transfer fixed-size chunks of bytes known as words. The number of bytes in a word (the word size) is a fundamental system parameter that varies across systems. Most machines today have word sizes of either 4 bytes (32 bits) or 8 bytes (64 bits).
- Each I/O device is connected to the I/O bus by either a controlleror an adapter.The distinction between the two is mainly one of packaging. Controllers are chip sets in the device itself or on the system’s main printed circuit board (often called the mother board). An adapter is a card that plugs into a slot on the mother board. Regardless, the purpose of each is to transfer information back and forth between the I/O bus and an I/O device.
- The best way to express a performance improvement is as a ratio of the form Told/Tnew, where Told is the time required for the original version and Tnew is the time required by the modified version.
- Processors that can sustain execution rates faster than 1 instruction per cycle are known as superscalar processors.
- Thread-Level Concurrency; Instruction-Level Parallelism; Single-Instruction, Multiple-Data (SIMD) parallelism.
Chapter 2 Representing and Manipulating Information
- 大端法：先存高位，小端法：先存低位。
- 通过三次抑或可以不借助第三个变量来交换两个变量的值。
- 待续…