One case would be configurable code. The code is copied to ram and then tweaked based on some parameters. The modified code runs faster than having a bunch of b

One case would be configurable code. The code is copied to ram and then tweaked based on some parameters. The modified code runs faster than having a bunch of branches to check/calculate result based on the parameters. It might even be easier to write that kind of code. Another case is to access a large range of memory, for instance, to fetch data from a large table. You have the code in ram and increment the high-byte address (HH) of a 'lda $HH00,x' or 'sta $HH00,x' to access larger ram area (because x index can only access 256 bytes). I've seen that in Vic-20 games, I don't know if NES games used it. One case is loop unrolling, a.k.a. speedcode. This is very common practice in modern 6502 demos. I don't think that the old NES games used it, but some modern NES demos may use it. See http://codebase64.org/doku.php?id=base:speedcode http://codebase64.org/doku.php?id=base:speedcode or http://csdb.dk/forums/index.php?roomid=11&topicid=96279&showallposts=1 http://csdb.dk/forums/index.php?roomid=11&topicid=96279&show...