Unsupported Applications

You cannot run the following types of applications with the OS/2 subsystem:

• OS/2 2.x applications.

• Presentation Manager (PM) applications (unless you install the Windows NT Add-On Subsystem for Presentation Manager, which can be ordered separately from Microsoft)

• Advanced video I/O (AVIO) applications (unless you install the Windows NT Add-On Subsystem for Presentation Manager)

• OS/2 applications on RISC-based computers.

• Applications that directly access hardware memory or I/O ports at Ring 2 or below.

For example, applications that directly access video memory to manipulate text or graphics are not supported. Some OS/2 applications, which rely on the statement IOPL=YES in the Config.sys file to run Ring 2 code segment, will run nevertheless under the OS/2 subsystem as long as the privileged instructions they issue in those segments are CLI/STI instructions and not IN/OUT instructions. For more details, see "I/O Privilege Mechanism" later in this chapter.

• You cannot run custom device drivers (those not included with OS/2 itself). These must be rewritten to the Windows NT device driver interface.

If you want to run an OS/2 application that is not supported, you have the following choices:

• If this is a bound application (one that can run under both OS/2 and MS-DOS), you can try to run it with the MS-DOS subsystem. To do so, run the forcedos command from the command line:

FORCEDOS [/D directory] filename [parameters]

where /directory is the current directory for the application to use, filename is the application to start, and parameters is the parameters to pass to the application.

• If this is not a bound application and you have the source code, you can recompile the source without the unsupported APIs, which are specified in the error message that is displayed when you try to run the application. If you don't have the source, contact the application's developer.