Hello.

my emu detects that load runner use horizontal mirroring. In this mode, everything written to 2000-27FF ($000) goes in name table 0 and everything written to 2800-2FFF goes to name table 1 ($400) right?

Well, turns out that the game is writing to both $2000-$2400 and $2400-$2800 for its 2 name tables, so everythig goes to $000 in my emu and the other name table is empty. Any idea what kind of error my emu suffers? Because on other horizontal mirroring games, it seems to work fine.

oups, that's *lode* runner, not load runner!

It uses vertical mirroring. As with so many other ROMs, the header is probably incorrect.
Your emu suffers no problem, you're completely right about how horizontal mirroring works.
/Nessie

Thanks, glad to see the problem was not on my side, but then how come it works flawlessly in most emus?

i don't know, perhaps they've thrown in a hack specifically for that game. Others maybe identify ROMs my their CRC32 and find accurate info in a database.
/Nessie

Yep, definitely sounds like a bad header.

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Be whatever the situation demands.

In horizontal mirroring, name table 0 and 1 are mirrored, so $2000-$23ff(nt0) = $2400-$27ff(nt1), and $2800-$2bff(nt2) = $2c00-2fff(nt3). And name tables are only $400 in size (if you also count the attribute table), so technically anything written past $23ff isn't supposed to go into name table 0 (unless its mirrored there).

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Be whatever the situation demands.

This is why before working on a specific mapper (or mirroring kind) I always check my games' headers on LissNES.

hydesprojects.cjb.net