This ROM is based on the upcoming 2015-2016 NBA season.
Using ESPN.com's depth charts, the rosters are accurate as of 9-15-15.
Most of the work was done using Emuware's Tecmo NBA Manager, however, there were many aspects of the game that couldn't be changed using the editor. For this, I used FCEUX's hex editor and Tile Layer Pro. Using these additional tools, I was able to update team logos (Oklahoma City Thunder and Washington Wizards), remove obsolete hairstyles (mustaches, boxy flat-tops) and replace them with more current head accessories (long hair, headbands, and Jahlil Okafor's exploding afro), replace instances of "1991-92" with "2015-16", and other miscellaneous items.
Along with roster updates, I (to the best of my knowledge) fixed the ratings to reflect the real-life counterparts. However, there is one small minor issue that doesn't affect gameplay, but can be annoying if you're all about 100% accuracy. There are some mercenaries in the game (Festus Ezeli, Mike Miller, Joey Dorsey, and Spencer Hawes) that try to ruin the simulation experience during season play. For some strange reason, these players, regardless of how I rate them (and they're relatively low-rated), end up leading the league in scoring with 30+ points-per-game every season. I don't know why this is. If you can ignore them, right underneath them will be Lebron James, Carmelo Anthony, Kevin Durant, Russell Westbrook, and the rest of the NBA elite. Like I said, it's just a small detail issue.
There are 27 teams in the game. Nashville, Toronto, and New Orleans were the three teams that were left out.