Preface

This document provides an understanding of the architecture and function of the Multiple Virtual DOS Machines (MVDM) component of OS/2 Version 2.0, which allows concurrent execution of multiple DOS applications, each in its own virtual DOS machine. Further, this document describes the support for Windows applications under OS/2 Version 2.0.

This document contains information on the MVDM architecture and components, including the use of device drivers by DOS applications, and support for expanded and extended memory. Other MVDM-related topics discussed in this document include the DOS Settings feature, which allows the user to determine the way in which a DOS application runs and the resources available to it, and Virtual Machine Boot, which allows the user to load any version of DOS into a virtual DOS machine to support the execution of version-dependent DOS applications.

Support for Windows applications on the OS/2 Version 2.0 platform is another important topic examined in this document. The document includes a discussion of Windows device drivers, inter-process communication between Windows, DOS, and OS/2 applications (including DDE and clipboard capabilities), and compatibility issues as they relate to Windows applications in the OS/2 Version 2.0 environment.

This document is intended for:

  • Customer planners and technical support personnel who require an understanding of DOS and Windows implementation in OS/2 Version 2.0.

  • IBM and IBM authorized dealer technical support personnel.

  • Programmers of DOS and Windows applications who wish to ensure compatibility of their applications with the OS/2 Version 2.0 platform.

    The information contained in this document assumes that readers have a general familiarity with the DOS and Windows environments and the applications which run in these environments.

    The code examples used in this document are available in electronic form via CompuServe** or through a local IBM Support Bulletin Board System (BBS), as package RB3731.ZIP. IBM employees may obtain the code examples from the GG243731 PACKAGE on OS2TOOLS.

    The document is organized as follows:

  • Overview provides a brief introduction to the topics covered in this document.

    This chapter is recommended for all readers of the document.

  • MVDM Architecture describes the architecture of the Multiple Virtual DOS Machines component of OS/2 Version 2.0, including information regarding the creation and management of virtual DOS machines.

    This chapter is recommended for those readers who require an understanding of the way in which OS/2 Version 2.0 manages virtual DOS machine resources and an understanding of how MVDM implementation differs from the implementation of the DOS Compatibility Box in previous versions of OS/2.

  • 8086 Emulation discusses 8086 emulation under OS/2 Version 2.0.

    This chapter is recommended for those readers who desire an overview of the 8086 emulation capabilities of the Intel 80386 processor, which are exploited by OS/2 Version 2.0, and who wish to compare the functions this environment provides to DOS applications with those available to DOS applications under previous versions of OS/2.

  • MVDM DOS Emulation describes the way in which DOS emulation is achieved by the MVDM component, and compares the functions available in a virtual DOS machine to those available in native DOS 5.0. Considerations for running a DOS application under OS/2 Version 2.0 versus running it under native DOS are also discussed.

    This chapter is recommended for those readers who wish to compare the VDM environment under OS/2 Version 2.0 with that of DOS 5.0.

  • Device Drivers discusses MVDM device drivers. It describes the device drivers which are supported in a virtual DOS machine under OS/2 Version 2.0 and explains how device drivers are implemented, differentiating between physical device drivers and virtual device drivers. Virtual DOS machine interrupt support is also discussed.

    This chapter is intended primarily for programmers who plan to write device drivers for DOS applications that will run under OS/2 Version 2.0 and for technical support personnel who wish an in-depth understanding of virtual DOS machine device driver support.

  • Memory Extender Support describes the support for DOS memory extenders provided in the MVDM component. This chapter explains expanded and extended memory support.

    This chapter is recommended for those readers who wish to understand the way in which MVDM supports applications which make use of more than 640KB of conventional memory.

  • Installing and Migrating Applications describes installing and migrating DOS and Windows applications to OS/2 V2.0 It also discusses the use of the utility for creating a customized migration database.

    This chapter is recommended for system administrators responsible for setting up applications for OS/2 V2.0 users.

  • Windows Applications describes the implementation of Windows application support under OS/2 Version 2.0.

    This chapter is intended for those readers who wish to run Windows applications under OS/2 Version 2.0.

  • DOS Protected Mode Interface describes the implementation of the DOS Protect Mode Interface, DPMI.

    This chapter is intended for those readers who wish to run Windows applications under OS/2 Version 2.0 and who also need a deeper understanding of the technical implications of this programming interface.

  • Running DOS Applications describes the way to define, configure and start DOS applications under OS/2 Version 2.0.

    This chapter is recommended for those readers who wish to run DOS applications under OS/2 Version 2.0, and who wish to define and configure their application environment for optimum compatibility and performance.

  • DOS Settings describes the DOS Settings feature of MVDM. This feature allows the user to customize parameters which affect how an application runs in a VDM and the resources available to it.

    This chapter is recommended for every reader who plans to run DOS applications under OS/2 Version 2.0.

  • Virtual Machine Boot describes the Virtual Machine Boot feature of MVDM, which allows a specific version of DOS to be started within a virtual DOS machine, thereby providing full compatibility for those applications which require version-specific DOS features.

    This chapter is recommended for readers who need to run such applications in a VDM.

    The following appendixes are included in this document:

  • Running Personal Communications/3270 Version 2 for Windows explains how to set up and run Personal Communications/3270 Version 2 for Windows in a WIN-OS/2 window.

  • Running DOS PC Support/400 in OS/2 V2.0 explains how to set up and run DOS PC Support/400 in a Virtual Machine Boot session.

  • Running Lotus 1-2-3 in a VDM explains how to set up and run Lotus 1-2-3 in a virtual DOS machine session with EMS or DPMI support.

  • Memory Extender Architectures provides a brief overview of the Lotus-Intel-Microsoft (LIM) Expanded Memory Specification (EMS) Version 4.0 and LIMA Extended Memory Specification (XMS) Version 2.0, for those readers who desire an understanding of these specifications in the context of their support by MVDM.

  • Multiple Virtual DOS Machines Lab Sessions provides a series of lab exercises designed to illustrate the new functions and features of the Multiple Virtual DOS Machines component of OS/2 Version 2.0. The exercises cover such topics as virtual DOS machine configuration, use of the OS/2 clipboard, virtual DOS machine device drivers, and virtual DOS machine video mode restrictions.

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