Err, scrap that i'm an idiot, tile # 2nd bit is A6, not A1. Somehow forgot some address lines are for the actual data
Check it it's shorted/floating
That's 273's pin 4, S1 pin 6.
Wow, i'm really off with this one, 273's pin 3, not 4 sorry
https://wiki.neogeodev.org/index.php?title=NEO-273