Computer software systems according to their functions can be divided into system software and application software into two categories.
1, system software
System software is the management, control, and maintenance of computer and peripheral equipment, to provide software and other aspects of the interface between the user and the computer, it is not tailored to the specific application problems.
Representative system software: operating systems, database management systems, and a variety of programming language compiler system, in which the most important system software is the operating system .
1) OS (Operating System)
The operating system is the basic system software, is a set of programs for managing and controlling all computer software and hardware resources. Operating system runs directly on bare metal, other software (including system software and a large number of applications) are built on the basis of the operating system and get its support and access to its services.
The operating system is the interface between the computer hardware and interfaces, but also other computer users and software.
Function : processor management, memory management, device management, information management and the like.
Operating performance of the system largely determines the performance of the entire computer system.
Category :
- By dialogue with the user interface different, it can be divided into a command line interface to the operating system and graphical user interface operating system ;
- By the number of users that can be supported as a standard, it can be divided into single-user operating system and multi-user operating system ;
- Press is capable of running multiple tasks as a standard, divided into single-tasking operating systems and multi-tasking operating system ;
- Press the system single function as a standard, it is divided into a batch system , time-sharing operating system , real-time operating system , network operating system .
2) language processing program
The computer program, when executed, first in the memory storing program instructions that want to be taken out one by one, and sends control signals to the respective components of the computer after decoding, it performs a predetermined operation. Instruction control apparatus can be recognized by the computer is written in machine language, a program written is not an easy task in machine language. The vast majority of users are using a programming language (ie, high-level language), language such as BASIC, C language to write programs. But these high-level language program of the CPU do not know, it must go through in order to be executed after the computer becomes a translation machine instructions. The program is responsible for this translation is called a compiler . To execute a program written by some high-level language on a computer, it must be configured with the languages of the build system .
3) database management system
Mainly it refers to the efficiency of the computer data processing efficiency.
Database management system functions : organized, store large amounts of dynamic data; enables a user to conveniently and efficiently using these data.
Database software system including database , database management systems and database systems in three parts.
- Database (DataBase, DB) in a range to meet the needs of many users, the establishment of a set of interrelated data set in the computer.
- Database management system (DataBase Management Systems, DBMS) refers to the database to organize, manage, query and provide certain software system processing capability. It is a core component of the database system, provides access to the database for the user or application, all database operations are carried out by the DBMS.
- Database system (DataBase System, DBS) is a database, database management systems, applications, database administrators, users, etc. Heng Gou man - machine system. Database Administrator is specialized in database construction, use and maintenance staff.
DBMS is software positioned between the user (or application) and an operating system. DBMS is running under the operating system supports, by means of the operating system to achieve the storage and management of data, data that can be shared by a variety of users, to ensure that users get the data is complete and reliable. The interface between it and the user is called the user interface, DBMS database language is provided to the user can be used.
4) utility
Utilities do some computer system resources and management and file-related tasks, such as diagnostics, anti-virus programs, uninstall programs, backup programs, file decompression program and other software tools.
2, application software
Application software refers to software designed to address specific problems in certain application areas and prepared (or utilities).
Application software generally can not run independently on the computer must have a support system software. Application software in particular, a variety of special packages are also often provided by the software vendor.
Common applications include the following categories:
- Word processing software : to enter, store, modify, edit, print text data (documents, articles, etc.). Commonly used WPS, Word, etc.;
- Information Management Software : used to enter, store, modify, retrieve all kinds of information. Such as payroll management system, personnel management systems. After the development of the software to a certain level, each individual software can be coupled together to form a complete, efficient management system, referred to as the MIS;
- Computer-aided design software : for efficient rendering, modify engineering drawings, a conventional design and calculation to help users seeking superior design. Commonly used with AutoCAD etc;
- Real-time control software : ready for operation state information collecting apparatus production, aircraft and the like, according to this embodiment and the automatic or semi-automatic control according to a predetermined scheme, so that safe, accurate task or achieve a predetermined target.
Finally, the hierarchical view, the composition of the computer system as shown below. Wherein the inner layer is bare metal without any software means (pure hardware) machine.
Relations at all levels is: an inner layer is the outer layer of the support, while the outer layer of the inner layer without having to know the details, just agree to use the services provided by the inner layer.
Computer software systems according to their functions can be divided into system software and application software into two categories.
1, system software
System software is the management, control, and maintenance of computer and peripheral equipment, to provide software and other aspects of the interface between the user and the computer, it is not tailored to the specific application problems.
Representative system software: operating systems, database management systems, and a variety of programming language compiler system, in which the most important system software is the operating system .
1) OS (Operating System)
The operating system is the basic system software, is a set of programs for managing and controlling all computer software and hardware resources. Operating system runs directly on bare metal, other software (including system software and a large number of applications) are built on the basis of the operating system and get its support and access to its services.
The operating system is the interface between the computer hardware and interfaces, but also other computer users and software.
Function : processor management, memory management, device management, information management and the like.
Operating performance of the system largely determines the performance of the entire computer system.
Category :
- By dialogue with the user interface different, it can be divided into a command line interface to the operating system and graphical user interface operating system ;
- 按能够支持的用户数为标准，可以分为单用户操作系统和多用户操作系统；
- 按是否能够运行多个任务为标准，分为单任务操作系统和多任务操作系统；
- 按系统单功能为标准，分为批处理系统、分时操作系统、实时操作系统、网络操作系统。
2）语言处理程序
计算机在执行程序时，首先要将存储在存储器中的程序指令逐条地取出来，并经过译码后向计算机的各部件发出控制信号，使其执行规定的操作。计算机的控制装置能够识别的指令是用机器语言编写的，而用机器语言编写一个程序并不是一件容易的事。绝大多数用户都是用某种程序设计语言（即高级语言），如BASIC语言、C语言等来编写程序。但是用这些高级语言编写的程序CPU不认识，必须要经过翻译变成机器指令后才能被计算机执行。而负责这种翻译的程序称为编译程序。为了在计算机上执行由某种高级语言编写的程序，就必须配置有该种语言的编译系统。
3）数据库管理系统
计算机的效率主要是指数据处理的效率。
数据库管理系统的功能：有组织的、动态的存储大量的数据信息；使用户能方便的、高效的使用这些数据信息。
数据库软件体系包括数据库、数据库管理系统和数据库系统三个部分。
- 数据库（DataBase，DB）是为了满足一定范围里许多用户的需要，在计算机里建立的一组互相关联的数据集合。
- 数据库管理系统（DataBase Management Systems,DBMS）是指对数据库中进行组织、管理、查询并提供一定处理能力的系统软件。它是数据库系统的核心组成部分，为用户或应用程序提供了访问数据库的方法，数据库的一切操作都是通过DBMS进行的。
- 数据库系统（DataBase System，DBS）是由数据库、数据库管理系统、应用程序、数据库管理员、用户等苟恒的人——机系统。数据库管理员是专门从事数据库建立、使用和维护的工作人员。
DBMS是位于用户（或应用程序）和操作系统之间的软件。DBMS是在操作系统支持下运行的，借助于操作系统实现对数据的存储和管理，是数据能被各种不同的用户所共享，保证用户得到的数据是完整的、可靠的。它与用户之间的接口称为用户接口，DBMS提供给用户可使用的数据库语言。
4）实用程序
实用程序完成一些与管理计算机系统资源及文件有关的任务，如诊断程序、反病毒程序、卸载程序、备份程序、文件解压缩程序等工具类软件。
2、应用软件
应用软件是指专门为解决某个应用领域内的具体问题而编制的软件（或实用程序）。
应用软件一般不能独立的在计算机上运行，必须要有系统软件的支持。应用软件特别是各种专用软件包也经常是由软件厂商提供的。
常见的应用软件有以下几类：
- 文字处理软件：用于输入、存储、修改、编辑、打印文字资料（文件、稿件等）。常用的有WPS，Word等；
- 信息软件管理：用于输入、存储、修改、检索各种信息。例如工资管理系统、人事管理系统等。这种软件发展到一定水平后，可以将各个单项软件联接起来，构成一个完整的、高效的管理系统，简称MIS；
- 计算机辅助设计软件：用于高效的绘制、修改工程图纸，进行常规的设计和计算，帮助用户寻求较优的设计方案。常用的有AutoCAD等；
- 实时控制软件：用于随时收集生产装置、飞行器等的运行状态信息，并以此为根据按预定的方案实施自动或半自动控制，从而安全、准确的完成任务或实现预定目标。
最后，按层次的观点，计算机系统的组成如下图所示。其中内层的裸机是指没有任何软件的（纯硬件）机器。
各层次的关系是：内层是外层的支撑，而外层可以不必了解内层细节，只需按约定使用内层提供的服务。