Large mapper 28 sizes are unsupported

[retroalarm]

The large .NES files from Action 53 Vol, 3 and 4 available from https://action53.itch.io/ do not load. Likely because the core does not support a huge file size for this.

[sorgelig]

Multigames carts on core is IMHO useless. Each such 999in1 cart may introduce its own mapper without any real benefit except just map of those included games to a virtual cart. Just find each game separately. I don't think it worth to spend effort and FPGA resources for something which is working in other cart version.

[greyrogue]

For what it's worth, I think the fix is just removing the bit mask from this line.
https://github.com/MiSTer-devel/NES_MiSTer/blob/master/rtl/mappers/generic.sv#L1142
It was intended to make it more accurate to original hardware boards that maxed out at 256K (although the mask there is for 512K, I think). Since the ROM size indicates non-original hardware boards won't work anyway, forcing the mask isn't really required.