While reconciling the Horizon Ramdisk ROS, CFG, and MENU programs I have been learning about GROM access. In all these years, I've never had much interest in GPL or GROM. That changed for a few reasons including the need to understand GROM to reconcile the source code and my curiosity of the magic that Tursi and Gazoo have been conjuring.
Since there is no better way to learn (IMHO) about something than to experiment with it, I found the source code for the 80-column Geneve version of BOO
Did you get my MAME image for the Geneve?
If so, at the MDOS prompt, type GPL. That will load the GPL interpreter and an 80 column menu program. When you hit the option to "Save", it will write out two(?) files with something like GPO/GPP to a disk device. I know I set it up to load a few things off of the TIPI on the Geneve before I sent my TIPI in to Greg to be updated. Now, I never tested it with cartridges, but it did run EA5 programs. I have no reason to believe it would