This patch has a major issue: the autosave doesn't work unless you walk to another level. If you close the game while standing on the same level (say, because you just died after a midpoint, or cleared a switch palace), it won't save.
Alcaro made an xkas autosave patch for me in 2011, which saves as soon as you gain control on the overworld, as well as when you walk to another level. I'm pretty sure he submitted it back then-- I wonder if something was lost in this SA-1 conversion? The code looks entirely different.