> it would mean it should have a BIOS able to cope with every
> possible memory module the user might plug in.

Pegasos II doesn't have a more advanced "BIOS" than the Efika 5200B. And while it can be picky about RAM it's not that hard to find Pegasos II compatible RAM modules, so it shouldn't be harder with a hypothetical Efika 5200B with RAM slot.