On: Leaving Arizona – the Story of the Motorola 6800 part 2 and creation of the 6502

[dietrichepp]

The main difference between X and Y is in the indirect addressing modes.

You can use X as an index when you are looping through an array of pointers.

You can use Y as an index when you are looping through an array, where you have a pointer to the beginning of that array.

There are also a couple operations that always use X as a source or destination. There’s TXS/TSX, but no TYS/TSY.

https://www.masswerk.at/6502/6502_instruction_set.html