[tyfighter]

EPROMs typically have a very, very long data retention lifespan, but nevertheless <B>could</B> lose data at some point.
For very old SGIs, the EPROMs on boards have held their programming since leaving the factory, and without their PROM images would never boot again.

I've uploaded binaries of the EPROMs on my IP17 and IO3B (captured by pulling the ROM chips directly), for the sake of preservation, in hopes that other owners of old rare systems would backup the EPROMs from them as well. They may even be useful some day.