INES Mapper 250

INES Mapper 250 is a mapper by Nitra, used for pirate games such as Time Diver Avenger and the Queen Bee V.

Hardware consists of regular MMC3 chip connected in different way:

• A10 instead of A0 is used to determine which register to write to (i.e. the registers are at $8000, $8400, $A000, $A400, $C000, $C400, $E000, $E400 and their associated
• A7..A0 is used instead of D7..D0: the value written to each register is the lower byte of the address (i.e. address AND $00FF), data value is discarded

• Queen Bee V contains also 74153 mux which controls PRG-A13 resulting in the following change:

below
$8000 $8000 $a000 $c000 $e000
   0   MMC3  MMC3   0     1

Source: [1]