From your file path was shown that you're on Windows.
For Windows Case:
The user profile folder or Home Folder is a place where DOSBox will look for the Dosbox.conf file for the user that executes dosbox.exe. The location of this folder varies depending on the host Operating System.
It appears that ..
Start > All Programs > DOSBox > Configuration > Edit Configuration
- Find this part
[autoexec] # Lines in this section will be run at startup. # You can put your MOUNT lines here.
- It appears in the file 'Dosbox.conf'.
Then you can add your part there after that part like this
[autoexec] # Lines in this section will be run at startup. # You can put your MOUNT lines here. mount c C:\PROGRA~1\OPAL c: OPAL LIB
Save then restart the DOSBox.
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For Mac Case:
You can go to the file
DOSBox 0.74 Preferences
It's in the path
~/Library/Preferences/
It suppose to be OSX with DOSBox 0.74 the lastest version now. Then, you can edit it with vi like this
sudo vi ~/Library/Preferences/DOSBox 0.74 Preferences
Or any way to edit it by TextEdit.
- Find the same part
[autoexec]
Then add it with your own configuration or something like these.
mount c ~/Documents/_DOSAP_/ c: dir
Then, restart the DOSBox. That's all.
(Ref : http://www.dosbox.com/wiki/Dosbox.conf and http://www.dosbox.com/wiki/User_profile_folder)