design of unix operating system

memory fragmentation is scary for devices with only a few m of memory. Even in some systems there is no interruption, interrupt processing is implemented by polling, so that the system state can be traced in real time.Such a small system needs to be accurate and reliable, some people say that they can write 8K lines of code in one months, you have to say, I said I can also write, the

Processes and ThreadsTwo features of the process concept:　　Resource Ownership : A process consists of a virtual address space that holds the process image (including programs, data, stacks, and process control blocks). Processes have control over and ownership of resources, including main memory, I/O channels, I/O devices and files, etc.;　　Dispatch/Execution : a process is executed along an execution path through one or more programs, and its execution may alternate with the execution of other p

library functions. In this mode, each process maintains a thread table that tracks the threads in this process, which contains resources that are exclusive to each thread in table 1, such as stacks, registers, states, and so on, as shown in 1.Figure 1 Thread implementation in user spaceThis mode calls the system procedure to block itself when a thread finishes its work or waits for it to be blocked, and then hands the CPU to another thread. User thre

and friendly service interface. The operating system is usually the closest to the hardware of a layer of system software, it is the hardware to transform the bare metal into a fully functional virtual machine, making the use and management of computer systems more convenient, more efficient use of computing resources, the upper layer of the application can be m

You know, only the choice of 64-bit server operating system and application Server software, 64-bit server to achieve a very good popularity and application, 64-bit server to "truly". The current tripod of Unix, Windows server, and Linux on 64-bit network operating systems has become increasingly apparent. While

addition, the scalability of this file system can meet the most demanding storage requirements.UfsUFS file system: a traditional Unix File System Based on BSD high-speed file system, which is the default file system of Solaris. U

applications are transplanted to Linux.* TCP/IP network protocol.* Various Internet client/server software.* X Window.* C/C ++, Java, and other language compilers.All of the above systems provide graphical interfaces, various network support tools, and other necessary tools. QNX is an operating system that is more in line with the traditional "distributed" concept. The goal is to turn the entire LAN into a

be the operating system corresponding to the fingerprint database with the "shortest distance. However, the obtained "distance" does not take into account some important marks of the TCP datagram header (such as SYN, ack, RST, Fin ......) . These tags often detect the running status of the target host. Serial number and validation number, which can be used to differentiate different

and simplify the process of hardware operations, and become the basis of the operating system. IBM launched IBM SYSTEM/360, a large computer, in 1964. They all share an operating system codenamed OS/360.(2) 80 's: microcomputer appears, they only need the most basic

advantages and disadvantages of several common operating systems; linux,windows 1. Microsoft provides the Windows operating system, currently the most widely used, by Windows XP and Windows 72, of course, there are other earlier versions 95, 98, server operating system

really appeared.3. Computer language:1) Machine language: The only language that can be directly recognized by a computer, consisting of 0 and 1 code. Difficult to remember and identify2) Assembly language: machine-oriented low-level languages, maintain the advantages of machine language, direct, concise. The machine does not directly recognize the program written in assembly language, it needs assembler to assemble assembly language into machine languages. such as: C language3) High-level lang

What is a shell? A shell is a special function program that is a interface between the core program (kernel) of the user and the Unix/linux operating system. Why do we say that the shell is an intermediary between the system's core program and its users? Readers who have read the introduction of operating systems know

, with multi-level indexes and integrated indexes. Multi-level index: UNIX three-level index structure: Access a file: file name-> file directory-> FCB-> Disk Improve file system performance: Disk scheduling: when multiple disk access requests are waiting, adjust the service sequence of these requests according to certain policies. Reduces the average disk service time, which is fair and efficient. Disk s

scripts such as ASP, there is no need to install Windows 2000/XP Internet Information Service IIS ), naturally, you can avoid such problems. PRINTER ,. IDQ ,. IDA, WEBDEV, and other external attacks through IIS. System Security sanjianke 1. Add a curtain for the "window" After using WSU to adjust the default account of the system, we effectively prevent attacks and damages from external cracking methods,

use and open-source, Linux has both powerful functionality and ease of transplantation, making it another option apart from Unix and Microsoft Windows operating systems. IBM, HP, and other large computer companies are using Linux and supporting the redevelopment of Linux. Since the birth of Linux in the past 20 years, it has been widely used as a server platform around the world, and the use of Linux as a

First to understand a few conceptsJob management, communication transaction management is the most direct service provided by the operating system to the user.Operating system Type: Single-user operating system, multi-channel batch processing

1. Definition and concept of computer operating system;The operating system (Operating system, or OS) is the program that manages the hardware and software resources of the computer, and is also the core and cornerstone of the com

end the user's request feedback satisfactory results. Without the coordination and command of the operating system, the computer will be paralyzed, not to mention the tasks the user has proposed. Therefore, the operating system can be defined as: direct control and management of computer

practical operating system books, so that if you want to see how others do it, apart from reading a very small number of books represented by "Operating System: design and implementation, that is, it is written into the source code, and the results are sometimes quite frust

. Next we will analyze the development trend from a complete Linux system architecture. Before that, we need to understand the system architecture of Desktop Linux. We can see that the graphical Linux is a Unix-like operating system. X-Windows must be used to bypass the cor