This is a good reference is you are looking for operating system to run on vary old hardware dating up to year 2000.
The great place to find out about what hardware is supported by Linux is at: https://docstore.mik.ua/orelly/linux/run/ch01_09.htm.
Article provides information on aspects of Linux requirements and hardware support. And is a place to learn about history of Linux.
So, don’t throw away your hardware form 20th century. Run Linux on it.
There are even more up to date articles on running contemporary Linux on old or low specifications personal computers.
To find up to date information on Linux running on old hardware follow this this link: https://duckduckgo.com/?q=old+hardware+requirements+for+Linux&t=canonical&atb=v192-1&ia=web.