I'm talking more codebase wise, not protocols, languages, specifications and franchises. For example, Wii U mario games aren't using code from the original 8bi

I'm talking more codebase wise, not protocols, languages, specifications and franchises. For example, Wii U mario games aren't using code from the original 8bit mario games. Same with most SMTP servers today. SMTP is old, the current implementations in use most of the time are not that old. I think many unix tools in use today like grep are probably not using the original grep implementations either. So I covered most of the list with UNIX (OSes), Oracle (DBs) and mainframes. I did miss compilers, vim & emacs but even that is being replaced by guys like LLVM.