Evie (ChickasaurusGL) 🌺 | Game Boy (DMG) boot ROM Rev 1 as opposed to Rev 0 cart handling comparisons @ChickasaurusGL | Uploaded December 2021 | Updated October 2024, 2 hours ago.
Notes: Non-Pokémon video, but relevant to Generation I and II Pokémon as they use the Game Boy. I show rev 1 and rev 0 in that order twice each in this video. Most Game Boy (DMG) boot ROMs are later than rev 0, but the rev 0 ROM is known to apply to very early Japanese Game Boys. On a limited number of emulators (such as BGB in the options menu here), you can test them.

As a comparison, rev 0 omits the "(R)" for some reason and doesn't handle bad Nintendo logo carts in the same way as rev 1; causing the screen to flash on and off. Rev 1 is the revision one with an original Game Boy would most likely have; instead the (R) appears and a glitched logo is shown instead of flashing on and off, if a logo (or glitched data) is read for the cart instead of the Nintendo logo. Note there are technicalities where an invalid logo gets through; for instance, it's either the top-half or lower-half of the logo that gets through one of the boot ROMs (if it matches the Nintendo logo; which lead to some pirates exploiting that), but I can't remember at the moment.

Source: gbdev.gg8.se