Some of the software supplied with the Professional Development System is “bound,” which means it runs under DOS or OS/2. However, five system components come in two versions: one for DOS (or OS/2 real mode), the other for protected mode for OS/2. These components are ML, PWB, NMAKE, QH, and CodeView.
If you set up for only one mode, it doesn't matter where you place these components. However, ML, PWB, QH, and NMAKE use the same name for their real- and protected-mode versions. If you set up for both real and protected mode, you cannot place these components in the same directory, because you cannot have two identically named files in the same directory.
Therefore, SETUP requires that you select different directories for the bound, real-mode, and protected-mode components. If you change SETUP default directories, be sure you don't choose the same directory for both the real- and protected-mode components.
Note that if you have chosen to install only for DOS or OS/2 real mode, you are not prompted for a protected-mode directory. Likewise, if you have chosen to install only for OS/2 protected mode, you are not prompted for a real-mode directory.