mapper4 There seems to be a problem

[ZhaoTonggang]

I tried to run some roms that support mapper4 mmc3, but some roms are gray screen. I found a similar project on github, but I don't know how to improve jsnes with it.
rom parameter:MMC3 rom: 16 PRG bank(s), 32 CHR bank(s)
project address:NesJS mmc3 Mapper

[allowing]

是有这个问题，我在弄"加纳战机"的时候，没有声音没有图像。

谷歌翻译：
There is this problem. When I was working on the "Ghana fighter", there was no sound and no picture.

[allowing]

@ZhaoTonggang 兄弟，我看你实现了几个mapper，我对这块不太熟悉，你能帮忙看看mapper 115 吗，我发现115和4很像，我尝试用4来代替，可以出现声音，但声音有点慢。

谷歌翻译:
Brother, I see that you have implemented several mappers, I am not familiar with this piece, can you help me to see mapper 115, I found that 115 is very similar to 4, I tried to use 4 instead, the sound can appear, but the sound is a little bit slow.

/**
* Mapper 115
*
* @description http://wiki.nesdev.com/w/index.php/INES_Mapper_115
* @example
* @constructor
*/
Mappers[115] = function(nes) {
    this.nes = nes;
};

Mappers[115].prototype = new Mappers[4]();