an operating system is a collection of system software that controls the running of other programs, manages system resources and provides an operating interface for users.
operating system (English; Operating System (OS) is a program that manages computer hardware and software resources, and it is also the kernel and cornerstone of computer system. Operating system is responsible for basic affairs such as managing and configuring memory, determining the priority of system resources supply and demand, controlling input and output devices, operating network and managing file system. Operating system is to manage all hardware resources of computer system, including software resources and data resources; Control program operation; Improve the man-machine interface; Provide support for other application software, etc., so that all resources of the computer system can play their roles to the maximum extent and provide users with a convenient, effective and friendly service interface. Operating system is a huge management control program, which includes five management functions: process and processor management, job management, storage management, equipment management and file management. At present, the common operating systems on microcomputers are DOS, OS/2, UNIX, XENIX, LINUX, Windows, Netware and so on. But all operating systems have four basic characteristics: concurrency, * * * enjoyment, virtuality and uncertainty.
the types of operating systems are very diverse, and the operating systems installed on different machines can range from simple to complex, from embedded systems of mobile phones to large operating systems of supercomputers. Many operating system manufacturers have different definitions of OS. For example, some OSs integrate a graphical user interface, while others only use a text interface and regard the graphical interface as an unnecessary application.
operating system theory is an active branch with a long history in computer science, and the design and implementation of operating system is the foundation and core of software industry.
[ Edit this paragraph] Types
Operating systems can be roughly divided into six types.
① simple operating system. It is the operating system configured in the early days of computers, such as the disk operating system DOS／36 of IBM and the operating system CP/M of microcomputers. The functions of this kind of operating system are mainly the execution of operating commands, file service, support for compiling programs in high-level programming languages and control of external devices.
② time-sharing system. It supports multiple users at different terminals to use a computer at the same time, which is independent of each other and does not interfere with each other. The user feels as if a computer is all used by him.
③ Real-time operating system. It is an operating system configured for real-time computer systems. Its main feature is that the allocation and scheduling of resources should first consider real-time and then efficiency. In addition, the real-time operating system should have strong fault tolerance.
④ network operating system. It is an operating system configured for computer networks. With its support, the computers in the network can communicate with each other and enjoy resources. Its main feature is to combine with the network hardware to complete the network communication task.
⑤ distributed operating system. It is an operating system configured for distributed computing systems. It is quite different from other operating systems in resource management, communication control and the structure of operating system. Because the resources of the distributed computer system are distributed on different computers in the system, the operating system's demand for users' resources can't wait for the direct allocation of resources like the general operating system, but it needs to search on all computers in the system and allocate them only after finding the required resources. For some resources, such as files with multiple copies, consistency must also be considered. Consistency means that the data read by several users for the same file at the same time are consistent. In order to ensure consistency, the operating system must control the reading, writing and operation of files, so that multiple users can read a file at the same time, and only one user can modify the file at any time. The communication function of distributed operating system is similar to that of network operating system. Because the distributed computer system is not as widely distributed as the network, and the distributed operating system also supports parallel processing, the communication mechanism it provides is different from that provided by the network operating system, which requires high communication speed. The structure of the distributed operating system is also different from other operating systems. It is distributed on all computers of the system, and can handle various needs of users in parallel, with strong fault tolerance.
⑥ intelligent operating system (see intelligent software).
[ Edit this paragraph] Functions
The main functions of the operating system are resource management, program control and human-computer interaction. The resources of computer system can be divided into two categories: equipment resources and information resources. Device resources refer to the hardware devices that make up a computer, such as CPU, main memory, disk storage, printer, tape storage, monitor, keyboard input device and mouse. Information resources refer to all kinds of data stored in computers, such as files, program libraries, knowledge bases, system software and application software.
resource management
The equipment resources and information resources of the system are allocated and scheduled by the operating system according to the user's requirements. The storage management of the operating system is responsible for allocating memory cells to programs that need memory for execution, and taking back the memory cells it occupies for reuse after the program execution. For the computer system that provides virtual storage, the operating system should cooperate with the hardware to do a good job of page scheduling, allocate pages according to the requirements of executing programs, transfer pages into and out of memory and recycle pages during execution.
processor management, or processor scheduling, is another important part of the operating system resource management function. In a system that allows multiple programs to execute at the same time, the operating system will alternately assign processors to the programs waiting to run in the system according to certain strategies. A program waiting to be run can only be run after the processor is obtained. If a program encounters an event, such as starting an external device and temporarily unable to continue running, or an external event occurs, the operating system will handle the corresponding event and then redistribute the processor.
the device management function of the operating system is mainly to allocate and recycle external devices and control external devices to operate according to the requirements of user programs. For non-storage external devices, such as printers, monitors, etc., they can be directly assigned to a user program as a device, and recycled after use for another user who needs it. For storage-type external devices, such as disks and tapes, storage space is provided for users to store files and data. The management of storage external devices is closely combined with information management.
information management is an important function of the operating system, mainly to provide users with a file system. Generally speaking, a file system provides users with the functions of creating files, revoking files, reading and writing files, opening and closing files, etc. With the file system, users can access data by file name without knowing where the data is stored. This practice is not only convenient for users to use, but also beneficial for users to enjoy public data. In addition, because the creator is allowed to specify the use rights when the file is established, this can ensure the security of the data.
program control
the execution of a user program is always under the control of the operating system. A user writes a program in a certain programming language to solve the problem he wants, and then inputs the program together with the requirements for its execution into the computer, and the operating system controls the execution of the user program until the end according to the requirements. The operating system controls users' execution mainly as follows: calling in the corresponding compiler, compiling the source program written in a programming language into a computer-executable target program, allocating internal storage and other resources to call the program into memory and start it, handling various events occurring during execution according to the requirements specified by users, and contacting the operator for instructions on handling related accidents.
Human-computer interaction
The human-computer interaction function of an operating system is an important factor that determines the "friendliness" of a computer system. The function of human-computer interaction is mainly accomplished by input and output external devices and corresponding software. The devices available for human-computer interaction mainly include keyboard display, mouse and various pattern recognition devices. The software corresponding to these devices is the part of the operating system that provides human-computer interaction function. The main function of the human-computer interaction part is to control the operation and understanding of the relevant equipment and execute the relevant commands and requirements transmitted through the human-computer interaction equipment. The early human-computer interaction facility was a keyboard display. The operator types the command through the keyboard, and the operating system executes it immediately after receiving the command and displays the result through the display. There are different ways to type in the command, but the explanation of each command is clear and unique. With the development of computer technology, there are more and more operation commands and stronger functions. With the development of pattern recognition, such as voice recognition, Chinese character recognition and other input devices, it is possible for operators and computers to interact at the level similar to natural language or restricted natural language. In addition, human-computer interaction through graphics also attracts people to study. These human-computer interactions can be called intelligent human-computer interactions. The research work in this field is being actively carried out.
[ edit this paragraph] operating system encyclopedia
early operating system (patent protection)
TRS-DOS, ROM OS's
Ti99-4
commodore PET, 64, and VIC-2,
the first set of IBM-PC
Apple computers
Sinclair Micro and QnX
non-Unix commercial operating systems
CPM operating system
MP/m-8
UCSD P-system
mini-flex
SSB-DOS
CP/ M-86
Dr-DOS
Freedos
MS-DOS
PC-DOS
MACH was researched by Kananiki Mellon University
L4 microkernel
Chorus
Choices
Multics
OS-9
.
Netware: a network server operating system
Unix and similar systems
A/UX(Apple UNIX).
Unix
Microsoft xenix
Chorus
Cromix
Uniflex
OS-9
IBM's AIX
BSD
FreeBSD
NetBSD
OpenBSD
Dragonfly BSD.
PC-BSD
Digital UNIX， That is, after Compaq Tru64
DNIX
HP's HP-UX
GNU/Hurd
SGI's IRIX
Inferno
Linux (or GNU/Linux)
MAC OS x
menuetos
minix
OSS. 1
Plan9
SCO UNIX
Sun's SunOS, later Solaris
System V
Ultrax
Unicos
Kylin operating system, The server operating system
OS/39
z/ OS
Syllable
Other
Acorn
Arthur
ARX
RISC OS
Amiga
Amiga OS
Atari ST
TOS
Multitos
Mint
. > apple computer (Apple/ Macintosh）
Apple DOS
ProDOS
Mac OS
Mac OS X
Mac OS X 1.4 Tiger
Mac OS X 1.5 Leopard
Mac OS X 1.6 Snow Leopard (Alpha )
pink OS
beos
a/UX
be
beos
beia
digital/Compaq
ais
OS-8
rsts/ E
rsx-11
rt-11
tops-1
tops-2
VMs (later renamed openvms)
IBM
OS/2
AIX
OS/4
OS. VSE
VSE/SP
VSE/ESA
OS/36
MFT
MVT
SVS
MVS
TPF
ALCS
z/ OS
PC-DOS
pink OS
Microsoft
MS-DOS
Xenix
Microsoft Bob
Windows based on MS-DOS operating system
Windows 1.
Windows 2.
. Windows 3.1
Windows 95
Windows 98
Windows ME
Win