Emulating “accurately” is so difficult that not even Nintendo’s Game Boy emulator on the Switch does it properly. I’ve been replaying old games and comparing some questionable moments with my original Game Boy, and the timings are not quite right in some cases.
For example in Link’s Awakening, there’s a wiggle screen effect done by writing to OAM during HBlank. On the Switch it lags very differently than my GB (try it by getting into the bed where you find the ocarina). Or with Metroid 2, the sound when you kill an Omega Metroid is different too. It pitch shifts along with the “win” jingle.
These have almost zero impact on playability. But for purists and emudevs it’s a popular pursuit.
> Emulating “accurately” is so difficult that not even Nintendo’s Game Boy emulator on the Switch does it properly.
The NSO emulators on Switch are particularly terrible, worse than past iterations on Wii etc. at least for some systems, for no obvious reason other than Nintendo being lazy and/or not preserving past emulation work on other systems and not wanting to reuse open source solutions.
There's a few good comparisons on Youtube such as youtube.com/watch?v=ounQZv1MFNA that go a bit more into the development history
They have a huge impact if you want to play light gun games on CRT, where timing being out by a few micro seconds prevents your light gun from registering at all
You cannot make 80s lightguns work on an LCD. When you pulled the trigger, the system drew out a few white boxes where the targets are, and how long it took the gun to "see" white told you which box you were aiming at, because of the raster functionality of the electron gun. LCDs always output an entire screen at once, so that cannot work.
For example in Link’s Awakening, there’s a wiggle screen effect done by writing to OAM during HBlank. On the Switch it lags very differently than my GB (try it by getting into the bed where you find the ocarina). Or with Metroid 2, the sound when you kill an Omega Metroid is different too. It pitch shifts along with the “win” jingle.
These have almost zero impact on playability. But for purists and emudevs it’s a popular pursuit.