[Villodre]

I wholeheartedly agree: some are against modifying these retro systems, but this opens up a whole world of possibilities.

I also got mine (AES and CD) directly from the author but he no longer provides upgrades via postal mail. Instead, he can send you your customised one by mail and flash it yourself.

[dleslie]

It's really not a serious modification, since the Bios sits in a socket and isn't soldered on.

And besides, very few functioning MVS systems haven't had some form of modification; at the very least, the timebomb-of-doom battery has likely been replaced with something that won't eventually leak and dissolve half the board.