What kind of memory does the device memory of modern smartphones belong to? Is it SRAM or DRAM, or some other kinds of memory? I think the device memory of smartphones is an analogy to RAM in personal computers (in terms of usage), except the former cannot be easily added or installed by user, while SD card of smartphones is an analogy to hard disks in PCs. So, is the device memory the same type of memory as the RAM in PCs?
p.s. Sorry if this question is off-topic. I think this is a question about computer organization and architecture, so it seems best suited to electronic engineering.