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NeTraverse Merge User's Guide
Appendix A, X server issues

Appendix A

X server issues
NeTraverse Merge works from a variety of X servers. You can run DOS and Microsoft Windows programs via remote X servers (also called X terminals or X workstations) just as you do from the Desktop on your local system console. Just as with any X client program, all that needs to be set is the DISPLAY environment variable, so that the window is displayed on the correct X server.

As installed, NeTraverse Merge is configured to work with the standard UNIX X server on the local system console. To use remote X servers or a different X server on the system console you will need to configure the X server and NeTraverse Merge. If this is not done, then there can be some reduced functionality.

The issues are:

X server "backing store"

For proper operation, the X server must have "backing store" enabled. How this is enabled varies between the various X server versions.

NOTE: XFree86 4.0 has backing store disabled by default.

When backing store is not enabled, then the Windows window will refresh slowly, leaving temporary black areas. In addition when doing some kind of screen switching it could leave the Windows window black.

Keyboard mappings

When running DOS or Windows session a mapping needs to be established between the keyboard codes of your X server and PC scancodes. When NeTraverse Merge is installed, the mapping is set for the standard console X server.

Note:

Keyboard mapping files

The keyboard code mappings are defined in special files with extension .xcode located in the directory /usr/lib/merge/xc directory. The file xcode.readme in that directory lists all mapping files provided with NeTraverse Merge along with which X terminals and X workstations they are for.

When NeTraverse Merge is installed, the default mapping file is put into the file "xcode.table".

To use a particular mapping file, a special X resource needs to be defined. For example, to use a mapping file named hp.enw.xcode, set the X resource as follows: 

Merge*xcodetable:		/usr/lib/merge/xc/hp.enw.xcode
(Various X terminals and X workstations use differing methods to set X resources, so you will have to refer to your X documentation to figure out how to set X resources.)

When using NeTraverse Merge via a remote X server, NeTraverse Merge uses a generic mapping scheme to translate X codes to PC scancodes if no mapping file is specified. If this generic mapping is not sufficient for your X terminal, a warning message will be displayed in the status area of your DOS or Windows window and certain keys may not work correctly. Note that this generic mapping scheme slows down the startup of each NeTraverse Merge session, so even though the generic mapping might be sufficient for your use, it is not pain free. But generally if the generic mapping scheme is used, some keys will not work properly, and these might be important keys.

Warning: In some situations in non-English locales, the generic mapping scheme does not work at all, and your NeTraverse Merge sessions will fail to start.

So for best performance you should get a new custom mapping file to use.

To make a new one, first look at an existing xcode file to see how it works. (In each file is an explanation of the format.) Then make a copy of one of the files, and update the "keycode" values in the copy to match what your X server uses. You can use the standard "xev" program to discover what the keycode values are so you can create your own xcode file. If you send your new xcode file to NeTraverse support, along with an explanation of exactly which X server version it is for, then it can be made available to other NeTraverse Merge users.

PC fonts

When a DOS session is run remotely, all the PC fonts it uses for DOS character mode display need to be installed on the X server that is displaying the session. If these fonts are not installed, alternates are used, but you may see funny characters, because standard X fonts do not have all the PC characters available. You may also see warning when starting up your sessions about a font not being available.

Note that this is NOT an issue when using Windows itself in a session, because the problem is with DOS fonts not Windows fonts.

The supplied PC font files are in the directory /usr/lib/merge/xc/fonts. These font files are in bdf format and must be compiled and installed according to the instructions for your X display server.

No VGA graphics

VGA graphics (640x480 16 color) for DOS applications are NOT available in an X window. VGA graphics are only available on the local VGA console via the zoom operation. If your application tries to switch to VGA graphics, then a message is displayes about VGA graphics are not available in a window. If this happens, all you can do is exit your session.