There are many reasons someone might want to peek into the memory contents of a core to see what is happening at a given memory address at a given time. The most common use is for awarding achievements, like those from RetroAchievements, but it can also be used for speedrunning/streaming assistant programs, machine learning applications, and more.
Cores that support memory monitoring can typically fetch and award RetroAchievements, but if a core is not specifically mentioned on the RetroAchievements team's official list of supported cores, there may be issues with some achievement-awarding logic not functioning properly or other unexpected behavior. Unsupported cores may be excluded from RetroAchievements' "hardcore" mode and leaderboards, as well. If you need to use an unsupported core to interact with RetroAchievements for whatever reason (e.g., on platforms where no officially supported core is available), please do not bother them with tickets or manual unlock requests, which will be closed without investigation. They are offering a free service through volunteer labor, and we should respect their time.
To be clear: the cores listed on this page support libretro's memory monitoring functionality but may or may not be supported by the RetroAchievements team. Please consult their official list of supported cores before requesting support from them.
External BIOS recommended, but no longer required. RetroArch 1.9.14 nightly or newer required for hashing to work. DSi mode currently is not supported for achievements.
Very high speed, but has not been thoroughly tested with achievements. A few games will fail to start or crash frequently. Please prefer other cores when device performance allows.
