Rewind is a feature found in many modern emulators. It continuously stores your game’s state in RAM. This way, it creates the equivalent of a recording of the X past seconds. Did your in-game character die? You can hold a key down to rewind the game and undo your wrong moves.
Installation
We assume you’ve installed Retroarch on your computer and configured it with your favorite emulator cores. Retroarch supports rewind from the get-go and has the hotkey r mapped to it. However, it doesn’t work, and the function is disabled. It doesn’t work for all cores, and on top of that, it demands memory to work. This means that the more demanding the emulated system is and the longer you want to rewind, the more RAM Retroarch will eat up. For relatively new systems, like the PlayStation, that hav more RAM than, for example, a Commodore 64, rewind can eat many MBs of RAM. That’s why rewind is disabled by default. To enable it, move to “Settings > Frame Throttle.” The rewind option at the top leads to a submenu. You’ll initially see only one option, Rewind Support, and it will be disabled. Switch it on, and more options will appear below.
Rewind Frames is initially set to 1 and will move backward in time at the same rate as when you were playing the game – one frame at a time. By increasing this value, you can speed up the rewind function by skipping frames. Since those frames aren’t recorded, this option also decreases the amount of RAM needed for rewind. The problem, though, is that the more frames you skip, the more you lose in granularity and control, and it will be harder to rewind to a specific spot. Rewind Buffer Size (MB) is the actual amount of RAM Retroarch will use for rewind. The initial size of 20MB is more than enough for emulating systems with low amounts of RAM, like most computers and consoles from the 8-bit era. For newer (emulated) hardware, it would be better to increase this number. The more recent the hardware, the more RAM you should allocate to rewind. At least, if you’d like to be able to go back in time for more than two or three seconds. Rewind Buffer Size Step (MB) defines the steps by which the previous option, Rewind Buffer Size (MB), increases or decreases. We guess it was too hard to implement some kind of numeric input directly in the previous option. The values we used for emulating SNES and Genesis-era games were 2 in Rewind Frames and 50 in Rewind Buffer Size (MB). Those afforded us more rewind time than we ever needed. We admit we didn’t measure it, but it felt like more than 5 seconds – and was surely enough to undo an in-game misstep.
Retroarch has the hotkey for rewind bound to r by default, but it doesn’t hurt to double-check.
Visit “Settings -> Input.”Find the Hotkeys entry and select it to enter that submenu. Locate the rewind entry and make sure it’s bound to r. If it isn’t, or you don’t like that mapping, feel free to change it by pressing Enter followed by the new hotkey when prompted.
Now you can turn back time!
With everything set up, fire up one of your favorite old-school games through Retroarch. We chose a classic Super Mario title for the SNES. When you’re in a similarly dire situation in your favorite game, press r on your keyboard (or any other hotkey to which you remapped rewind). Continue holding r (or an alternate hotkey) and check your screen as time flows backward. Let up on the key when you reach the spot where you’d like to continue, and game on! As a closing note, keep in mind that rewind is not supported for all cores in Retroarch. Thankfully, most popular systems have multiple cores available, and at least one will probably be compatible with rewind. There’s always the chance the feature is entirely unavailable for a particular system through Retroarch’s cores, though. In such cases, it’s worth looking into dedicated emulators, like Dolphin and FS-UAE, which may might support the feature for your favorite retro-system. Meanwhile, also check out how you can set up Retroarch on Android.
