Download Arcade Rom
Currently I have a 32 GB SD Card for RetroPie and a 128 GB USB stick with all the game ROMs running from it, ie My current issue is getting MAME working. I found and downloaded the reference set of FB Alpha, but it is 24.5 GB. That won't fit on my current 32 GB SD Card. I am going to download the 'Non-Merged MAME 0.78 ROM Set' next and that will need even more space. Do I need to buy a larger SD Card, or can I put the reference set on the USB and have RetroPie find and use it at boot time (like the game roms)? If I do need to buy another SD Card, what is the recommended size so I never need to buy a bigger card in the future?
MAME Roms To play MAME roms, an emulator is required. Popular MAME emulators include MAME32 v0.90 for Windows, Nebula v2.23c for Windows, Kawaks v1.63 for Windows. 
View all MAME emulators. Guides: Video: How to play MAME roms.
To be sure I can fit every possible BIOS/reference set/etc onto it. Is a 128 GB SD Card enough, or should I go for a 256 GB and be sure I won't need to upgrade again in the future? Thanks for any tips to help get this going. OK, I think I am confused. I already have a bunch of MAME game ROMs. Most of them start, black screen for a few seconds and then back to RetroPie.
Download Arcade Roms Jojo Heritage For The Future
After some searching I saw that I need the BIOS's for MAME so the ROMs work (or at least more of them run). I thought I read that the 'non merged' sets have the BIOS needed. But it looks like I am downloading another full set(s) of game ROMs to run with mame4all and fbalpha. Do those full sets include the required BIOS files?