Chapter 1 - A Tour of Computer System

• Files such as hello.c that consist exclusively ASCII characters are known as text files, while all other files are known as binary files.

• In order to run the hello.c on the system, the individual C statements must be translated by other programs into a sequence of low-level machine-language instructions. These instructions are then packaged in a form called an executable object program and stored as a binary disk file.

• Assembly language is useful because it provides a common output language for different compilers for different high-level languages.

• The hello.o files is a binary files whose bytes encode machine language instructions rather than characters.

• Buses are typically designed to transfer fiche-sized 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).

• I/O devices include disk drive. Each I/O device is connected to the I/O bus by either a controller or an adapter. 

• Memory is organised as a linear array of bytes, each with its own unique address (array index) starting at zero.

• At CPU core is a word-sized storage device (or register) called the program counter. At any point in time, the program counter points at (contains the address of) some machine-language instruction in main memory.
• Register file doesn't refer to register, but consists of a collection of word-sized registers, each with its own unique name.
• Only a few simple operations revolve around main memory, the register file, and the arithmetic/logic unit (ALU).

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