> As far as I remember, the message pops up when the debug/test mode is
> enabled on machine boot.
I believe you're thinking of this (from src/mame/drivers/pacman.c):
- Pacman, Ms Pacman, Piranha and similar display "MADE BY NAMCO" sideways in power pellets. Hold start 1 and 2 and
toggle the test switch to get to the convergence grid. 4xUp, 4xL, 4xR, 4xD.
right after that comment is this:
- Ms. Pac-Man has a hidden message at the very end of ROM memory 0x97d0-0x97ff:
000097d0: 4745 4e45 5241 4c20 434f 4d50 5554 4552 GENERAL COMPUTER
000097e0: 2020 434f 5250 4f52 4154 494f 4e20 2020 CORPORATION
000097f0: 4865 6c6c 6f2c 204e 616b 616d 7572 6121 Hello, Nakamura!
H@P