Computer system roaming (ii)

1. How a program works

For example, after the hello: input./hello, the shell reads the characters into the register and then places it into the memory when the Enter button is pressed

The shell knows the input is over, it loads the hello through a series of instructions, copies the hello target file from the disk to main memory, enters the inside

Post-Save Execution instructions

2. Cache

Multi-level cache to solve the problem of transmission, hard disk, hard disk cache, main memory, multi-stage cache, the existence of the cache can improve program performance

Number

3. Computer operating system

The operating system abstracts the use of all hardware resources into the service of the operating system itself, so that users do not care about hardware details.

Operating system features: To prevent hardware misuse by the program, to provide users with a unified simple interface. Primarily through the need for all levels of

Abstraction is divided into: job management, storage management, device management, process management, file management. The operating system kernel is the medium of the hardware and the program he provides is three abstract, the file is the abstraction to I/O, the virtual memory is the abstraction to the main memory and the disk, the process is to the processor,

Main memory, abstraction of I/O devices. Network communication is also abstracted as an I/O

4. Abstraction of the operating system

Process: An abstraction of a running program by the operating system, which switches between the upper and lower doors to run different processes, making the process appear exclusive

Virtual Storage: He provides a process with an abstraction that only one process uses main memory

File: An abstraction of all IO devices, and network communication is abstracted as a file operation

5. Parallel technology improves system speed

Thread-level parallelism

Instruction-level parallelism

Single instruction, majority data parallel

　　

Computer system roaming (ii)