Still on the learning curve with this. Trying out familiar stuff to familiarise myself. Installed Mame via !PackMan and spent the next hour trying to get it working. Fresh eyes today tells me there's something very wrong with the install. Rummaging RISCOS and MAME turns up http://www.iconbar.com/forums/viewthrea ... adid=11873 with a link to http://www.cgransden.co.uk/mame.zip which looks like a complete install.
I can only deduce that the one referenced in the RISCOS repository is incomplete.
Going to try this .zip file and report back.