Configuring DOS emulation

The default settings of the DOS emulator will work for most people, but there will always be games that require EMS or large amounts of conventional memory, which aren't provided by default. Under plain MS-DOS, the configuration files autoexec.bat and config.sys are used to load devices and set up memory allocation. These live on under Windows XP, albeit with slight changes to the file names and syntax.

Windows XP uses two files when you start up the DOS emulator; config.nt is the direct replacement for config.sys and autoexec.nt is XP's equivalent to autoexec.bat. Getting the most memory available for DOS applications involves creating your own config.nt and autoexec.nt files - the steps below show you how to get enough base memory and EMS to run almost anything.

• Run notepad and paste the following text into the window:

@echo off
SET BLASTER=A220 I5 D1 P330 T3

• Save the file as "autoexec.nt", including quotes, in a directory of your choice.
• Go to File>New and paste in the following:

dos=high,umb
device=%SystemRoot%\system32\himem.sys
emm=ram
files=20

• Save this as "config.nt", again including the quotes. (Some games may require more file handles; if this happens to you then change the files= line above to files=40 or however many file handles are needed. This will use extra conventional memory, though).

This gives you a bare bones DOS setup, including setting up Soundblaster emulation. Next, follow the steps below to create a shortcut icon for DOS, with the config files you've just created:

• Right click on an empty part of your desktop and select New>Shortcut.
• Type in command as the location of the program to run.
• Type a name for the shortcut or accept the default.
• You should now have a new icon on your desktop. Right click the icon and select Properties.
• Click the Program tab and select the Advanced button
• Change the filenames in the dialog to point to the location of the files you created earlier in Notepad. While you're here, tick the 'Compatible timer hardware emulation' checkbox.
• Press OK to return to the Properties dialog.
• Click the Memory tab and select the amounts of XMS and EMS that you require - or choose the options above if you're not sure.
• Click on the Misc tab and clear the ticks in the checkboxes of any shortcut keys that are used by your games. This stops you returning to Windows when you least expect it, just because you've pressed Alt and Space during the game! Click OK to exit the dialog.
• Double click on the icon you've created to enter (emulated) DOS.

• Using the settings above, I've ended up with over 600K of conventional memory, as well as copious amounts of EMS and XMS - perfect for most games.

Note: some games, such as those that use DOS extenders to access extra memory, won't run with the above setup - you'll get an error message such as the one below.

If this happens, either type dosx at the DOS prompt or include the following in your autoexec.nt file:

lh %SystemRoot%\system32\dosx

Note: the default settings for the DOS emulator include the following line in autoexec.nt; if you get CD related errors in DOS games then you'll need to add the following to your autoexec.bat file.

lh %SystemRoot%\system32\mscdexnt.exe