You're right. I thought the term 'SSD' implied NAND-based memory. According to Wikipedia, it doesn't at all have that implication. It lists examples of "Early SSDs using RAM and similar technology":

> In 1976 Dataram started selling a product called Bulk Core, which provided up to 2 MB of solid state storage compatible with Digital Equipment Corporation (DEC) and Data General (DG) computers.[16] In 1978, Texas Memory Systems introduced a 16 kilobyte RAM solid-state drive to be used by oil companies for seismic data acquisition.[17] The following year, StorageTek developed the first RAM solid-state drive.[18]