CHAPTER 1 : A Tour of Computer Systems

1.1  informaiton is Bits + Context

• the hello.c program is stored in a file as a sequence of bytes.

1.3 it pay to understand how compilation systems work

• optimizing program performance.
• we do need  a basic understanding of machine-level code and how the compiler translates different C statements into machine code.
• understanding link-time errors.
• avoiding security holes.
• data and control informaition are stored on the program stack

1.4 processors read and interpret instructions stored in memory

• Bus : buses that carry bytes of information back and forth between the components.
• I/O Device : input/outut devices are the system's connection to the external world.
• Main Memory : the main memory is a temporary storage device that holds both a program and the data it manipulates while the processor is executing the program.
• Processor :  the central processing unit(CPU), or simply processor, is the engine that interprets instructions stored in main memory.  using a technique known as direct memory access(DMA), the data travel directly from disk to main memory, without passing through the processor.

1.5  Caches Matter

• a major goal for system designers is to make these copy operations run as fast as possible.
• larger storage devices are slower than smaller storage devices.