I wouldn't count on it.
http://krikzz.com/forum/index.php?topic=368.msg3450#msg3450
....And I see people still are STILL mislead in believing that lame ass excuse from 2006 that Disch gave. *sigh*
Welcome to 2015 people and Mapper 90 has been completely documented and is not harder to implement than mapper 5.
If I were Krikzz I would use the NEStopia, FCEUX and MESS sources along with Kevtris's documents on it to implement it.
I don't known if it helps but FCEUX emulator support mapper 90. Maybe it can be ported from source.
Yes, but ported to FPGA VHDL. Perhaps someone in the NES hacking community (NESdev, Romhacking.net, etc) can help with porting some of the more complex mappers, instead of not implementing it at all. I see this question gets asked all the time here, and obviously will continue to do so. Most of the pirates on mapper 90 (along with mappers 116, 121, 123, 187, 209, and 211) belong to Hummer Team, whose pirates are of surprisingly decent quality (by pirate standards, of course

) and are worth playing. A lot of other mappers like Mapper 83, the Cony Soft mapper, is not worth implementing.