SoftRAM was a fraud (https://en.wikipedia.org/wiki/SoftRAM ), but RAM Doubler (https://tidbits.com/1994/01/10/ram-doubler/ , https://www.amazon.com/Connectix-R010836-RAM-Doubler-9-0/dp/...; “Currently Unavailable”) worked, and modern OSes may still use the technique of, instead of swapping out memory pages, compressing them so that a page becomes available (https://en.wikipedia.org/wiki/Virtual_memory_compression)