Running or virtualizing DOS-era software can be non-trivial: see, for example, Windows 98 vs TLB cache invalidation behavior in modern CPUs https://blog.stuffed

Running or virtualizing DOS-era software can be non-trivial: see, for example, Windows 98 vs TLB cache invalidation behavior in modern CPUs https://blog.stuffedcow.net/2015/08/win9x-tlb-invalidation-bug/ https://blog.stuffedcow.net/2015/08/win9x-tlb-invalidation-b... requiring a patch. Any code that does loop counting to estimate cycles for sleep() will also overflow (hello, Pascal CRT Error 200!) requiring a different patch.