In 1988, GCC 1.27 was released, the first version supporting the x86 CPU. A blog post by Mikhail Maltsev detailed building and using this 29-year-old compiler on a modern system. Updating paths and configurations for a 64-bit Ubuntu system was necessary, despite issues with the ancient GCC version not understanding system headers. Enabling the DBX debug format and implementing various command options worked surprisingly well, with modern tools handling the code generated by GCC 1.27 smoothly. Building this compiler on a 64-bit Ubuntu Desktop 16.04 involved installing multilib support, downloading source code, applying patches, configuring symbolic links, and building it in two or three stages.
http://kristerw.blogspot.com/2019/01/building-gcc-127.html