A significant aspect of OS/2 2.0 is its ability to run multiple DOS sessions along with OS/2 sessions, using the multiple-DOS-sessions feature. This feature enables each session to run as a single-threaded, protect-mode OS/2 task. Each DOS session can have more than 620KB of conventional memory available. OS/2 supports the use of the Lotus/Intel/Microsoft Extended Memory Specification (LIM EMS) and the Lotus/Intel/Microsoft/AST eXtended Memory Specification (LIMA XMS). The ability of a DOS session to run within a window on the OS/2 desktop provides immediate productivity gains to existing DOS applications, because they can use OS/2 desktop features. These features include window manipulation and the ability to cut, copy, and paste information between applications, using the OS/2 clipboard.
Application compatibility in the DOS session is improved over previous OS/2 versions. The DOS session can be used to run DOS-based communications applications and other applications that address hardware I/O devices through the use of virtual device drivers (VDDs). These VDDs map the device driver calls from applications to the appropriate physical device driver within the operating system. For more information, refer to "Virtual Device Drivers."
Application compatibility is further enhanced by the DOS Settings feature, which allows DOS sessions to be customized to suit the requirements of the applications running in them. Settings, such as video characteristics, hardware-environment emulation, and the use of memory extenders, can be customized using this feature. For more information, refer to "DOS and WIN-OS/2 Settings."