Stella-DS Improved

There is always interest

There was some Save Support in the original Stella code that was mostly disabled and I've removed it as part of my cleanup but it could be added back. Lots of other pressing priorities on this stuff first, however!

 

Interestingly enough, for the 2600, the higher resolution would only hurt. The specs on the Atari 2600 are 320x192 though most games don't use all 320 as the older TVs would often cut them off at the sides... the 192 was also a guideline to avoid cutting off the tops and bottoms on some ancient TVs (remember, they were still dealing with a load of Black/White TVs in 1977) - but most games utilized more than 192 and it was generally for sky/ground effects that didn't affect gameplay.

So for the 2600, the 3DS native 320×240 resolution won't buy much as the DS/DSi 192 pixels is sufficient to show the games 1:1 on the 2600. Mostly you would just end up with black bars top and bottom on the 3DS (like watching old widescreen DVDs on a 4:3 TV).

Plus, I don't own a 3DS so it would be hard to test

 

Version 1.9: https://github.com/wavemotion-dave/StellaDS

Screen scaling/tweaks to more than 400 games to make them look as good as possible on the DS screen.
AR/Starpath Supercharger games got a nice 10% speedup with some optimization - more of those games are now playable.
General cleanup and polish ... pretty happy with this one now!

 

Not ready for a new build, but the nightly check-in has a new build with improved Starpath Supercharger support. That stuff is tricky and I'm working on getting the games running at full-speed. With the latest check-in, half of the games run at full speed and the other half run close enough to be playable... I think the only real holdout is "The Official Frogger" which is still running down in the mid 40 FPS and needs some help... It's been a significant effort getting it this far but I think it's worth it. Although the Supercharger (which allowed playing Atari games from data stored on Cassette Tapes) only has a library of 12 games, many of them were shining examples of what was possible on the system.

 

Version 2.0: https://github.com/wavemotion-dave/StellaDS

Okay, significant improvement on the Starpath (Arcadia) Supercharger front and the emulation in general. I discovered something important - I had gone a little hog-wild using (otherwise unused) Video Memory for various things because it's faster (not quite as fast as the "Tightly Coupled Memory" but there's a ton more of the Video Memory to play with). This is true ONLY if you are accessing the memory in 16-bit (or 32-bit) chunks... 8-bit access is actually not all that efficient. I had put some of the scanline buffers into video memory and it was only a "win" in emulation speed if the game had otherwise simple backgrounds where I could draw in chunks of 16 or 32 bits - games like Adventure were benefiting from this. But simple background games were all running way faster than necessary anyway... I was so fixated on getting Adventure to run full-throttle over 150FPS that I didn't stop to realize that it came at the expense of the more complicated games that were not yet achieving 60FPS. So I reversed that course - and now Adventure (which had seen peaks of 155FPS) is now running about 142FPS - still more than 2x what is needed. But much harder to run games like Phaser Patrol and The Official Frogger have gone from low 40FPS to 50+FPS and that's a huge win as it now makes them playable (though just barely).

Anyway, enough rambling. Version 2 is here! More than 800 games (original games + homebrews) are in the compatibility list now.

 

Just an update. Nothing new to release - I have found a couple of if/then clauses that could be simplified in the main emulation loop that buy us a bit less than 1% speedup... but it's something.

I'm really squeezing blood from the proverbial stone at this point. Unless I'm willing for a complete re-write, I don't know if I can get any more speed out of this emulator. In short: I think we're at the limit of my skill here. It's almost 200% faster than the initial version I started with and with improved compatibility - and the vast majority of Atari games run at full speed on the DSi and a reasonable handful of simple games run fine on the original DS hardware.

The Atari 2600 has been really difficult - more so than the 5200 or the Atari 8-bit where things aren't nearly as wild and wooly. The 2600 has such limitations on the system side that a huge number of games take measures to add bank switching and extra RAM and other crazy schemes built into the cartridge itself which need special handling. All of these edge cases make it difficult to optimize for a single path. I'm still pretty happy with where this ended up. I will put out a new build with the tiny tweaks (and one bugfix) soon.

Hopefully a clever developer will pick up the mantle on this and move the ball forward!

 

Version 2.1: https://github.com/wavemotion-dave/StellaDS

As promised. Improved screen scaling to more closely match the other Atari DS emulators I've worked on. Bug fixes in the file/rom selection (plus the increased speed of loading large directory listings). Improved info screen and a last few tweaks to bring the speed up as much as possible. This has come a long way in 4 months - Enjoy!

 

It's been quite the adventure - I only set out to add difficulty switches to the emulator and ended up putting in more than 100 hours of development effort - about half that was learning how to program the NDS