36-pin female 0.1"-spaced dual-sided card edge connector at the console.
Be careful about throwing any of those emulator ROMs you downloaded onto EPROM so you can play them on your 5200. You'd think that the 16K files would take addresses 4000-7FFF. Not so. Those files actually have the contents of two 8K ROMs, the first taking addresses 4000-5FFF, and the second taking 8000-9FFF. And sometimes only the second 8K is needed, since the first 8K may be blank or an exact duplicate of the second 8K.
Likewise, the 32K ROM files may or may not take all the space between 4000 and BFFF. Some of them take 4000-5FFF then 8000-BFFF, and some may only take 8000-BFFF. Again, many of the files have blank or redundant blocks.
Anyway, just have a good look at the files before burning your EPROMs.