Getsufuu Maden LH17 KS-7021A
$8000: [....PPP.] (mask: $E000)
$9000: [.......M] (mask: $E000)
$B000..$B007: [.CCCCCCC] (mask: $F007)
[url=http://wiki.nesdev.com/w/index.php/NES_2.0_Mapper_525]NES 2.0 Mapper 525[/url]
Note the inverted CHR-A16 (ROM is dumped using MyKazzo, so it omits that); take it into account when trying to re-use original and/or mask ROM.