[maxvu]

I'm guessing it's the ROM for the system. Poke various hardware bits, map the cartridge and jump to a certain address within it.

If memory serves, it also checksums the Gameboy logo-intro at the start of every game cartridge -- subjecting non-licensed game publishers to additional copyright claims.

[phkahler]

>> If memory serves, it also checksums the Gameboy logo-intro at the start of every game cartridge -- subjecting non-licensed game publishers to additional copyright claims.

That is quite clever! Don't run without a valid logo, and therefore violate a trademark or copyright if your game is to run without permission. It's like DRM but enforced legally not technically.

[toast0]

It's clever, bur probably doesn't hold water legally, see https://en.wikipedia.org/wiki/Sega_v._Accolade

[MikeRichardson]

Seems like you could easily find some random garbage image that also happens to pass the checksum.

[monocasa]

It doesn't actually checksum, but instead has a verbatim copy and does a memcmp over both.

[bogantech]

It reads the image twice, once for the checksum test then again when actually displaying it - so it's even possible to show a different logo by replacing that data in-between