What Are the Different Types of Digital Computer Systems?

A digital computer is a computer that performs operations represented by data represented as discontinuous forms.

A digital computer is a computer that performs operations represented by data represented as discontinuous forms. It is usually composed of computing unit, controller, internal memory and external equipment. The so-called electronic computer usually refers to a general-purpose electronic digital computer. Digital computers are characterized by large storage capacity, high precision, and strong processing power.

The hardware and software of a digital computer are combined into a unified body, called an electronic computer system. ^[1]

Modern electronic digital computers are an extremely complex system. A large electronic digital computer is a huge system composed of tens of thousands of integrated circuit components, thousands of various types of connectors, and dozens of external devices. Such a system can perform various functions under the control of software. The normal operation of the system is not only related to whether the hardware and software constituting the system are correct, but also to the environment in which the system is located, such as temperature, humidity, electromagnetic interference, and so on. According to the statistics of the electronic digital computer operation at home and abroad, according to the various forms of failure, the failure can be classified as follows:

Digital computer system system failure

This is a global failure that affects the operation of the system. At this time, the system has the following situations: stop or never stop; the system can execute the program, but the result is always wrong. These situations are likely to be encountered by operators or programmers in the computer room. System failure is also divided into fixed failure and accidental failure. If after the system failure occurs, the system resumes normal operation by using the restart function, it means that the system failure is accidental. Conversely, if the restart is abnormal, the system needs to be repaired or replaced before the system can resume normal operation. At this time, it is called a fixed failure.

Digital computer system hardware failure

A hardware failure mainly refers to a failure caused by the operating parameters of the physical devices constituting the system deviating from its normal performance, or being completely broken at all. For example, a failed component causes a hardware failure. This kind of hardware failure may be fixed or it may appear accidental. This is discussed in more detail below.

Digital computer system logic failure

A logic fault is also called a logic error. It appears that the logical relationship between the input and output of the logic component is incorrect. Logical faults are classified according to their duration, which can be divided into two types of accidental and fixed. According to the fault scope, it can be divided into two categories of independent multiplication. The so-called fault range mainly refers to how many logic variables in the logic component have errors. Among these logical variables that have errors, their errors can be independent, that is, the error of one variable does not affect the contribution of another variable; it can also be related (or called distributed), that is, the error of several variables Are interconnected. According to its value, logical faults can be divided into two categories: deterministic and uncertain. The so-called definite logic fault refers to a logic fault value that is always 0 and 1; the so-called uncertain logic fault refers to a logic fault whose value changes between 0 and 1.

Digital computer system software failure

In the operation of the system, software failures do not refer to those caused by hardware failures or logical failures. They are manifested in software failures, but refer to errors inherent in the software itself. In a sense, software failures are caused by errors in software design and implementation. In the software production of modern computers, due to the complexity of software engineering, the lack of a certain scientific methodological foundation, and a set of scientific and reasonable production systems, it can be said that software errors are almost inevitable. Software reliability has become an important issue of common concern.

System failures, hardware failures, logic failures, and software failures are closely related. This is because the system is an organic combination of software and hardware, and the logic components are composed of various individual hardware. Therefore, in general, a hardware failure will cause a logic failure, and a logic failure will eventually cause a system failure. But there are also differences between them. For example, incomplete logic faults are caused by hardware faults, unreasonable time margins in the logic design, and the presence of electromagnetic interference can cause logic faults. ^[6]