Well, what did you expect from programming?

Mersenne Numbers aren't that hard to understand as the the formula is "2^n - 1" (and most people in computer sciense will know the formula before the name). What makes them special in base 2 (and therefore programming) is that consecutive bits from zero to a specific bit are set (i.e. 0x01 has bit 0, 0x03 has bits 0 and 1, 0x07 has bits 0, 1 and 2, etc. set). The advantage of using these values is that performing a modulo in base 2 is pretty easy with these numbers since you just have to perform an "AND #$MN" (with MN being the Mersenne Number).

That being said, 0x7F

Mersenne Numbers aren't that hard to understand as the the formula is "2^n - 1" (and most people in computer sciense will know the formula before the name). What makes them special in base 2 (and therefore programming) is that consecutive bits from zero to a specific bit are set (i.e. 0x01 has bit 0, 0x03 has bits 0 and 1, 0x07 has bits 0, 1 and 2, etc. set). The advantage of using these values is that performing a modulo in base 2 is pretty easy with these numbers since you just have to perform an "AND #$MN" (with MN being the Mersenne Number).

That being said, 0x7F

*should*work as normal as that's 0b01111111 or 2^7 - 1.