You have piqued my interests. About a month ago I was looking at ring core memory on Ebay with a mind to get one and make it work.
Those rings are not ordinary ferrite. They are a special type of ferrite that has very strong hysteresis characteristics.
But what I am wondering is why you might be interested in making magnetic core memories work?
I cannot tell you why, actually. The only thing I can say is wondering about what is contained in the technology of equipment from days of yesteryear. Sorry.