As I understand it from the documentation, Ultracade came in 4 flavours -- Uprights with 27" VGA, Cabaret with 19" VGA, Cocktail with 25" CGA and a conversion kit (compatible with CGA, EGA and VGA).
First step is to determine which you have, particularly in terms of the monitor. Manuals are available online from GlobalVR:
http://service.globalvr.com/ultracade.aspWhile I would love to see someone rework the dedicated computer and, particularly the interface card, that may be more hassle than it would be worth (unless you really like digging into stuff like that ... you may have some driver issues and I haven't heard of anybody breaking the security on the Joshua OS), so I would concur that you should sell the dedicated Ultracade stuff and drop in a normal PC and interfaces.
It looks like the Ultracade is wired to connect via JAMMA harness (with button 4 wired in the harness), with additional connectors on the interface card for buttons 5 and 6 (similar to the JPac), so I would definitely use a JPac for interfacing between the cabinet and the PC. If you have a trackball, I don't know how the interfacing works for Ultracade and can't find any documentation on it, but I would presume that it is a standard arcade trackball that connects to the interface card via some sort of wiring harness. You would need an optical interface to connect to to your PC (Optiwiz, Optipac, etc).
Depending on the monitor you have, you may or may not need a special video card or software solution to drive the monitor at the appropriate resolution and frequency. If you have a CGA (aka standard resolution) monitor, then you can use an ArcadeVGA or a software solution like Soft15Khz. If you have an EGA (aka medium resolution) monitor, then I think you are stuck needing an ArcadeVGA. If you have a VGA monitor, then you can use whatever you like ... just stick to the supported resolutions.
