I like how they don't mention what's in the 0xE000-0xFDFF range at all, it's just p͈̮͇̦r̥̫o̧h̹̘͔͙͉̰̳͠ib͚͕̞̠̘i̝̝̩̦̲̠͇t͖̦̣͟e̻̭͓̪̳̤d͈ͅpic.twitter.com/TeJNuxDpWr
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ROM not RAM
C000 to DFFF is RAM. It's a mirror of that region.
Since it is mapped from ROM, did you try writing there? I might be wrong but I remember in the DOS times I were not able to store anything there, it being READ ONLY MEMORY. That is not being in protected mode.
Games seemingly do use it for whatever reason.
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