I've had a bit more time to investigate my booting issue and it seems to be overzealous EFI security on the particular motherboard I have. I can boot a USB key and install GA just fine. For some reason, as soon as my motherboard boots something else other than the drive that GA was installed to, it'll refuse to boot GA again. I'm guessing it's some security feature to stop office people booting their own USB keys at work.
Right now I'm trying to figure out a way to make vertical games look good on a vertical 15kHz 9:16 monitor. Setting
'aspect 16:9' in
mame.ini seems to do the trick, as it'll display most games at the proper 3:4 resolution but with black bars at the top and bottom. I am currently trying to create a layout file that will use the unused space (all 100 or so pixels of it), but I'm having a few difficulties with resolution.
So I boot up a game, lets say Time Pilot and go to machine information:
If I'm reading that right, it says the native res of Time Pilot is 224x256 and the current videomode is 224x344. So I generate a 224x344 PNG to use as a bezel and the following layout file:
<!-- timeplt.lay -->
<mamelayout version="2">
<element name="bezel">
<image file="timeplt.png" />
</element>
<view name="Bezel Artwork">
<bezel element="bezel">
<bounds left="0" top="0" right="224" bottom="344" />
</bezel>
<screen index="0">
<bounds left="0" top="0" right="224" bottom="256" />
</screen>
</view>
</mamelayout>
But when I load up MAME with the resulting files it decides to change the resolution from 224x344 to 244x464 and adds in another set of black bars:
My hunch is that the aspect 16:9 in mame.ini is forcing the black bars each time, but I'm not really sure how to fix it/make it work.
EDIT: Yep, needed to set 'aspect 4:3' on the games I want to use bezel artwork with.