= Rewind feature =
ACE-DL has a rewind feature, but it is not as good as it could be: [https://youtu.be/wIKGvpnJLUo Demonstration of rewind in ACE-DL]
Only the The RetroArch CPC emulator has a proper the most convenient rewind feature: [https://youtu.be/YwilYlSe5LQ Demonstration of rewind in RetroArch]. To reverse the game, the user press and hold the rewind button. And at any point, releasing the button makes time goes forward again. ACE-DL also has a rewind feature, but it is not as good as it could be: [https://youtu.be/wIKGvpnJLUo Demonstration].
One 128KB snapshot per frame allows 10 seconds of rewind with 64MB (128KB * 50 frames * 10 seconds) of memory for the rewind feature. A more efficient method saves only the previous RAM values that are changed between 2 frames, allowing much longer rewinds (even if the CPC is equipped with 4MB RAM expansion) while using less memory, as shown by the GBA emulator [https://youtu.be/Sfc_1NKbiKg SkyEmu].
