Deitel - The design of OS/2

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Deitel, Harvey M., 1945

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Virtual MemoryDynamic LinkingMultitaskingI/O Management8Q286/80386/80486SAA

Micro ChannelArchitectureMultiprocessingOSI

LAN SupportProcessesMultimediaThreadsOpen SystemsShared MemoryMultiuser OS/2Windows CompatibilitySemaphores

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Foreword by

IBM Vice President and General Manager,Personal Systems

Named PipesPortability

Presentation ManagerInstallable File SystemsPaging

SegmentationDevice DriversIBM PS/2TCP/IP

DOS Compatibility

16-bit OS/2

Scheduling

Interprocess

Communication

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To the designers, implementors, and testers of OS/2:

For bringing edge-of-the-art distributed computingcapabilities to the desktop of the 1990s

To Dean Edward Simco:

For his indefatigable efforts in creating and nurturing theCenter for Computer and Information Sciences at Nova University

Digitized by the Internet Archivein 2018 with funding fromKahle/Austin Foundation

https://archive.org/details/designofos20000deit

It is a pleasure to write these opening comments for Deitel and Kogans, The Design ofOS/2. We at IBM believe strongly that the new 32-bit OS/2 2.0 will have an importantplace in the market for personal computers, workstations, and network servers. The bookclearly and thoroughly explains the architecture of the operating system in a manner appropriate both for technical professionals who want to understand OS/2s internal structure, and for software developers considering investing in OS/2 applicationsdevelopment. It provides insights into why various key design decisions were made.

Dr. Michael Kogan is the chief architect of OS/2 2.0; Dr. Harvey Deitel is the authorof one of the worlds most widely used operating systems textbooks. Their combinedexperience covers every major current IBM operating system, as well as the UNIX system, networking, multimedia, and open systems. Dr. Kogan, through his position at IBM,is well apprised of IBM architectural trends. Dr. Deitel consults in the open systems arenawith activities related to open operating systems, object orientation, OSI protocols, andinternational computing and communications standards.

Why OS/2?

Computer systems are evolving rapidly, and OS/2 is designed to support these changes.There are radical changes in hardware, from older systems supported by modest 8- or16-bit microprocessors, to newer high-powered 32-bit microprocessors such as the Intel80386 and 80486. RISC systems and multiprocessing systems offer the potential formassive increases in net processing power.

Radical changes in user support also are demanded. The personal computers of theearly to mid-1980s tended to be standalone systems. In the 1990s, personal computerswill be networked in local and wide area networks. OS/2 is designed to support mission-critical applicationsthat is, applications that must function continuously and reliablyto support key activities of businesses and other organizations. OS/2 is designed to enhance personal productivity. End users working in OS/2 environments can get moredone because of the ease of use, high performance, high reliability, information accessibility, and system integrity provided by OS/2.

VI

Foreword

The shift in application development toward object-orientation is gaining momentum. To become more productive software developers need to reuse components, to develop prototypes more rapidly, and to implement polished and tuned applications faster.OS/2 provides an environment conducive to object-oriented systems development.

The following sections briefly describe OS/2 2.0 and its capabilities. As you readthis book, you will come to understand what is under the hood, and how these capabilities are implemented.

The Integration Platform

We call OS/2 2.0 the integration platform because you can run your existing DOSapplications, DOS extender (such as the popular Windows) applications, and OS/2 1.3applications on OS/2 2.0, and they will run more efficiently on the same hardware thanthey do under their originally intended operating systems. You can also run the new,high-performance 32-bit applications designed to take advantage of 32-bit architectures.Applications run better from the standpoint of performance, integrity, and usability,translating into productivity gains.

Protected Multitasking

OS/2 2.0 represents the evolution of DOS into the world of protected multitasking. Ituses the protection mechanisms of the 80386/80486 architecture to ensure robust operation. It runs many applications simultaneously without the danger of misbehaved applications destroying one another or the operating systemprecisely what is needed inmission-critical application environments. An application may not access the privatedata of other applications. This level of protection is facilitated by the fact that OS/2applications execute in separate address spaces; DOS extender applications, on the otherhand, share a single address space. An errant DOS application may destroy a DOSextenders kernel, thus requiring a reboot, and work may be lost; the OS/2 kernel is protected from errant applications. OS/2 can run multiple versions of the same softwaresimultaneously, making it ideal as an application developers platform. Its multitaskingcapabilities make it appropriate as a network server. It uses preemptive scheduling, so itoffers good responsiveness to applications of differing characteristics. Priorities are calculated dynamically, so OS/2 can multitask timing-critical applications in both the foreground and the background.