Some additional details about NES related stuff for anyone interested.
The earlier APU is found in MAME's Famicom clones 'famicomo', 'famitvc1', and in the VS. system games (and in arcade games like dkong3, but it makes no difference there) and lacks the so-called tonal noise of later APU revisions. Having an early APU fixes a few bugs in games like VS. Gumshoe (percussion line) and VS. Bungeling Bay (jet sounds). It's also apparent that several early Famicom games are meant to be used with it. Examples of Famicom sound differences are Balloon Fight (last note in game over jingle), 1942 (player plane being destroyed), Warp Warp (player gun shots), Bungeling Bay (jets again), etc. Going in the other direction, check out Solstice (triangle-like percussion in start of game music) or Mega Man 2 (Quick Man stage) using the famicomo driver to hear the way that early Famicom adopters must have missed out.
A couple RGB Famicom clones have snuck in under the radar: 'fctitler' and 'famitvc1'. The former is marked as not working, but the Famicom bits all work fine. The latter as noted has the old-style APU sound. Outside of the PlayChoice-10 games these clones represent the first time the whole NES/FC library has been available in MAME with the RGB PPU. Note that some games, such as The Immortal, do NOT work with the RGB PPU. Your mileage may vary. Here's an example of our normal Famicom palette and the RGB palette side by side:
There are a handful of games that support saving and loading to and from cassette. These are the BASIC cartridges and a handful of games with built-in level editors: Arkanoid 2, Castle Excellent, Excitebike, Lode Runner, Mach Rider, Wrecking Crew. A few have been fixed and should now all work AFAICT. Also, there's a new expansion port device, the Sharp Cassette Interface, that seems to be used exclusively by the built-in ROM of the famitvc1. This thing must have predated Nintendo's own Data Recorder. Anyway, that is now available too, so you can save your doodles and katakana messages you write on your emulated TV C1 to tape
Store Display Units:
Lastly, there are the M8 store display units, just in case you wanted to play early NES games and have them annoyingly reset to a timer (20 sec, 3, 6, or 25 min). Set 3 looks historically interesting as it included 16 of the 17 October '85 launch titles for the US release of the NES. There is scant information about the M8 units so I wasn't able to figure out exactly when this earliest machine debuted. So there you have it. PS beware the DIP switches.