[toast0]

> Would it be cheap to make a RAM chip from like 15 years ago? Or would it just not even work with our modern hardware?

Modern CPUs have built in memory controllers. Most of them can only talk to a small variety of memory; maybe DDR4 or DDR5 and sometimes a LP variant. If you wanted to make DDR3, you'd also need a special CPU with a DDR3 compatible memory controller.

I think once production stops for a given memory type at a specific fab, they get rebuilt for a new type of RAM. It doesn't make sense to keep the stuff around because there's been enough DDR3 ram made for the rest of time.

It's different for other fabs, where old lines can remain valuable for lower cost production.