Comment by MayeulC
3 years ago
I've really wanted something like that where I could just drop my old RAM sticks and use it as swap space.
It would be much better than flash-based solutions, both latency and endurance-wise, probably even over an USB link (3.1 and above speeds are pretty decent, even 3.0 would be enough for basic swap).
Bonus points for a DIMM slot that just accepts any generation (DDR2,3,4, not sure if that would be mechanically possible?). I retired some DDR4 sticks for higher frequency ones, but the 8GB DDR4-2400 stick I have in the drawer would be quite welcome as swap space on the 4GB soldered RAM laptop I am using...
I may have a go at it myself, I don't think the controllers would be too complex if writing a custom kernel driver, and targetting USB speeds.
It wouldn't be mechanically possible to support multiple generations[1]. That's not the only issue with mixing generations.
There are also some interesting electrical engineering problems around driving the bus as you add more SIMMs; probably need multiple CPLD/FPGA memory controllers beyond a certain point. Clocking gets interesting as well. Not impossible, just complicated for an amateur; I know I have problems getting thing to work reliably over 33MHz or so.
[1] https://www.simmtester.com/News/PublicationArticle/168