...as far as space we have about 0.040 chip height to play with and are using TSOP now
Height isn't the problem; we know theres enough room underneath for Flash / Ram chips. (Rams are same height at Flash; Flash chip fit underneath, so there's no problem).
The problem is surface area; only about 1/2 of the top area is available for mounting chips. A large programmable chip might use all/most of that. You would have to find one with enough gates to duplicate the arcade card registers, and a small enough area to fit on the board.
I know only that programmable chips exist, and come in different gate counts. IIRC (and I may not), number of gates is proportional to surface area, so more gates == bigger area.
IMHO, you should only need a fairly simple FPGA/CPLD to do the Arcade Card ... your problem is more going to be in the number of I/O pins that you need, and the total number of individual IC chips ... trying to fit a CPLD, ROM, and 2 RAM chips into the space that you've got is going to be ... interesting.
As far as CPLD/FPGA/RAM choices, well you don't have that many anymore if you're talking about using 5V parts ... and if you're going to use 3.3V parts, then you're going to need to add level-shifters too, which is going to take up more space.
Is the Arcade Card Pro really that rare that it's worth going to all that trouble?
Give it 5-10 years and the whole PC Engine/CD/Arcade Card will all be emulated on FPGA hardware anyway.
A cheapArcade Card is out of the question, considering the price of these relatively simple straight-game HuCards already. But this physical format might be ideal for the kind of "super" Arcade Card that developers have been asking for. To make translations and various projects easier.
Errr ... don't we already have that "super" Arcade Card with the Turbo Everdrive 2?
It's got 4MB RAM, built-in SD card, and built-in USB (for a few dollars more).
I don't see that there's been a rush of new translations/homebrew that have been started since I released the patch that gives the TED2 512K of easily accessible RAM for the Super System Card (and you can access the whole 4MB if you actually follow the programming details that I posted).