96 Operating systems 96.1 96.2 Types of Operating Systems 96.3 Distributed Computing Systems 6.4 Fault-Tolerant Systems 96.6 Real-Time Systems 96.7 Operating System Structure Joseph Boykin 96.8 Industry Standards Clarion Advanced Storage 96.1 Introduction An operating system is just another program running on a computer. It is unlike any other program, however. An operating systems primary function is the management of all hardware and software resources. It manages processors, memory, I/O devices, and networks. It enforces policies such as protection of one program from another and fairness to ensure that users have equal access to system resources. It is privileged in that it is the only program that can perform specialized hardware operations. The operating system is the primary program upon which all other programs rely To understand modern operating systems we must begin with some history [Boykin and LoVerso, The modern digital computer is only about 40 years old. The first machines were giant monoliths housed in special rooms, and access to them was carefully controlled. To program one of these systems the user scheduled access time well in advance, for in those days the user had sole access to the machine. The program such a user ran was the only program running on the machine It did not take long to recognize the need for better control over computer resources. This began in the mid 1950s with the dawn of batch processing and early operating systems that did little more than load programs and manage I/O devices. In the 1960s we saw more general-purpose systems. New operating systems that provided time-sharing and real-time computing were developed. This was the time when the foundation for all modern operating systems was laid Today's operating systems are sophisticated pieces of software. They may contain millions of lines of code and provide such services as distributed file access, security, fault tolerance, and real-time scheduling. In this hapter we examine many of these features of modern operating systems and their use to the practicing engineer 96.2 Types of Operating Systems Different stems(oS)provide a wide range of functionality. Some are designed as single-use and some for multiple users. The operating system, with appropriate hardware support, can pi executing program from malicious or inadvertent attempts of another to modify or examine its men rotect one connected to a storage device such as a disk drive, the OS implements a file system to permit storage of files. c 2000 by CRC Press LLC© 2000 by CRC Press LLC 96 Operating Systems 96.1 Introduction 96.2 Types of Operating Systems 96.3 Distributed Computing Systems 96.4 Fault-Tolerant Systems 96.5 Parallel Processing 96.6 Real-Time Systems 96.7 Operating System Structure 96.8 Industry Standards 96.9 Conclusions 96.1 Introduction An operating system is just another program running on a computer. It is unlike any other program, however. An operating system’s primary function is the management of all hardware and software resources. It manages processors, memory, I/O devices, and networks. It enforces policies such as protection of one program from another and fairness to ensure that users have equal access to system resources. It is privileged in that it is the only program that can perform specialized hardware operations. The operating system is the primary program upon which all other programs rely. To understand modern operating systems we must begin with some history [Boykin and LoVerso, 1990]. The modern digital computer is only about 40 years old. The first machines were giant monoliths housed in special rooms, and access to them was carefully controlled. To program one of these systems the user scheduled access time well in advance, for in those days the user had sole access to the machine. The program such a user ran was the only program running on the machine. It did not take long to recognize the need for better control over computer resources. This began in the mid- 1950s with the dawn of batch processing and early operating systems that did little more than load programs and manage I/O devices. In the 1960s we saw more general-purpose systems. New operating systems that provided time-sharing and real-time computing were developed. This was the time when the foundation for all modern operating systems was laid. Today’s operating systems are sophisticated pieces of software. They may contain millions of lines of code and provide such services as distributed file access, security, fault tolerance, and real-time scheduling. In this chapter we examine many of these features of modern operating systems and their use to the practicing engineer. 96.2 Types of Operating Systems Different operating systems (OS) provide a wide range of functionality. Some are designed as single-user systems and some for multiple users. The operating system, with appropriate hardware support, can protect one executing program from malicious or inadvertent attempts of another to modify or examine its memory. When connected to a storage device such as a disk drive, the OS implements a file system to permit storage of files. Joseph Boykin Clarion Advanced Storage