First post, by MiniMax
Just read your guide. Seems you have gotten the problem with the \ (backslash) mixed upsidedown:
Q) I have a German, Spanish, or other non-English keyboard, and / doesn’t work in DOSBox.
A) Simply use the \ instead. Or, go to the Control Panel->Regional & Language Options->Language Tab and set the Keyboard to United States – International.
Forward slash (/) is not the problem, backslash (\) is.