Dedicated system

Introduction

Dedicated system refers to application software or system software developed by software developers for certain industries. Many systems are used in practice, such as real-time systems, monitoring systems, and hospital information systems. Dedicated systems are generally developed for some special requirements, such as information security, reliability, and real-time.

System software

System software refers to the software used for the management, monitoring and maintenance of computer resources, as well as the interpretation and operation of various application software. System software is the necessary software for computer systems. The main characteristics of the system software are: strong interaction with computer hardware systems, scheduling and management of shared resources, and solving coordination problems in concurrent operation processing. The data structure in the system software is complex, and the external interfaces are diversified, which is convenient for many users to use repeatedly. Common system software includes: operating system, database management system, language processing program.

Application software

Application software refers to a software system specially prepared for a certain application purpose. Commonly used application software includes word processing software, table processing software, statistical analysis software, and database Management system, computer-aided software, real-time control and processing software, and other applications used in various industries of the national economy. Programs written to solve various computer problems are called application software, which can be divided into special software and general software.

Special software

Special software refers to software specially developed for certain units and industries. It is developed by users to solve specific specific problems. The scope of use is limited to certain Specific units and industries. For example, the ticket management system of the railway station or the bus station, the personnel management system of the personnel management department, and the financial management system of the financial department.

Universal software

Universal software is an independent system with rigorous structure carefully designed to realize a certain special function. It is a set of software that meets the needs of many users of the same kind. . General-purpose software adapts to the application requirements of various fields in the information society, and applications in each field have many common attributes and requirements, and are universal. For example, the Office 2003 general software package released by Microsoft includes general software such as Word 2003 (word processing), Excel 2003 (electronic spreadsheet), PowerPoint 2003 (slides), Access 2003 (database management). Starting from Chapter 3, we will learn the specific operations of Office software

Purpose

Reliability

Reliability is the reliability of the computer system under specified conditions. The ability to complete the specified function within the specified time. The prescribed conditions usually include environmental conditions, use conditions and maintenance conditions. The prescribed time is the time range under consideration. The prescribed functions refer to the various technical performance indicators of the computer. The capability is under the prescribed conditions and within the prescribed time. The extent to which the prescribed function is completed. Reliability can be quantified by reliability and mean time between failures. Reliability design generally follows the following principles: under the premise of meeting performance and function requirements, put reliability in the first place; under the premise of meeting performance and function requirements, optimize the structure; implement the standardization, serialization and modularization of design Principles to facilitate system expansion and compatibility between version numbers.

Real-time performance

Real-time performance means that the clock signal can be accurately timed, and the clocks everywhere can reach the same level. In different occasions, it needs to reach the ns level and the μs level. Real-time can be defined as: the system's ability to react within a specified time. Generally, applications with real-time requirements have two outstanding characteristics: the activities are time-sensitive, requiring information collected from the external environment at a certain moment and or within a certain period of time, and then responding in a timely manner.

Information security

Information security refers to the technical and management security protection adopted for the data processing system to protect computer hardware, software, and data from accidental or malicious reasons It was destroyed, altered, and revealed. This not only contains the concept of level, in which computer hardware can be regarded as the physical level, software can be regarded as the operational level, and then the data level; it also contains the concept of attributes, where damage is related to availability, and changes are related to Integrity, revealing involves confidentiality. The basic requirements for information security are as follows:

Data confidentiality

Because the system cannot confirm whether there are unauthorized users intercepting data on the network. This requires the use of a means to treat the data confidentially. Data encryption is used to achieve this goal. The encrypted data can ensure that it is not illegally obtained by a third party during transmission, use, and conversion. After the data is encrypted and transformed, the plaintext is turned into ciphertext. Only authorized legal users can restore the ciphertext to plaintext through the decryption algorithm using their own key. Data confidentiality can be said to be the basic guarantee for many security measures. It is divided into network transmission confidentiality and data storage confidentiality.

Data integrity

Data integrity is a feature that data cannot be changed without authorization, that is, only those who have permission can modify the data. And can determine whether the data has been modified. The data in the storage or the data after transmission over the network must be exactly the same as the content before the last modification or transmission. Its purpose is to ensure that the data on the information system is in a complete and undamaged state, so that the data will not be stored and transmitted due to the process. It is changed, destroyed and lost by intentional or unintentional events. The system needs a way to confirm that the data has not changed during this process. This change may come from natural disasters, intentional and unintentional behaviors of people. Obviously, it is not enough to use only one method to ensure the integrity of the data. On the basis of the application of data encryption technology, a comprehensive use of failure contingency plans and a variety of preventive technologies, such as archiving, backup, verification, crash dump, and failure Precursor analysis and other means to achieve this goal.

Data availability

Data availability is a feature that can be accessed by authorized entities and used on demand, that is, the attacker cannot occupy all resources and hinder The work of the authorizer. If a legitimate user needs system or network services, the system and network cannot provide normal services. This is the same as the documents are locked in a safe, the switch and password system are confused and cannot be taken out.