Weird thing with Master System Emulation

[William]

Alright this is kind of weird actually When i play certain Masters system games on Kfusion they slow down a run at like half the speed. It only happens with some game like Star Wars and quack attack. With other games like Ninja gaiden or Dracula it does not happens at all.

I thought that I had the fps configured wrong or something like that so I checked that but when the games slo down the fps are still shown as 60.

So then I thought well mabe there is something worng with the roms so i tried downloading fresh roms. But the same thing happened.

Then I tried other Emulators. But still same problem.

And every other rom on every other emulator runs pretty much as it should.
So I wonder if somebody knows what's going on and how i can fix it.

[FatTrucker]

If it only happens on certain games and it happens at the same point in the same games even when using different roms and different emulators, it sounds like the slowdown may have actually occured on the original machines playing those titles, so the emulation is actually working perfectly.

Slowdown was a problem from time to time when things on screen got busy. The Master System in particular suffered from slowdown on a lot of titles. I can still remember various games doing it on my original system.

[William]

Yeah FatTrucker I must admit that what you just said had crossed my mind as wel. But I only had a Nintendo when I was little so I dont know how fast the games did run on the Master system.

But still it kind of sucks, Becouse allot of games really look much beter that the Nintendo version. It's a shame that they are allot slower

[ulaoulao]

Nes too, they all did..

The NES doesn't slow down and flicker automatically. Actually what happens is that as a game becomes more complex, and more objects are introduced into the play area, there is not enough time in one frame (1/60th of a second) to calculate all the action for one frame. The NES CPU runs at about 1.79 Mhz, not quite fast enough for some calculations. In fact, if the calculations spill over to the next frame, oftentimes a game will glitch or freeze up. So, the programmers put slowdown into the game to split the calculation between successive frames.

Flicker is usually a result of having too many sprites in one horizontal scanline. The NES can have a maximum of 8 sprites in one line. Any more than that, and the PPU simply won't display them. Thus, the programmer has to alternate between displaying one set of sprites and another. This is handled through a good algorithm of "OAM Cycling". Depending on the OAM algorithm used, the sprites might either flicker (as in many Konami games), or blank out with a rippling effect (seen in some games).

-From another source