I know all that - I was there and I saw products like these in person (although they were in the megabyte range back then). I still remember a 5.25 hard-drive shaped box with a lead acid battery and lots of memory boards with 4164's (IIRC).
These are only for when the OS and the machine itself can't deal with the extra memory and wouldn't know what to do with it, things you buy when you run out of sensible options (such as adding more memory to your machine and/or configuring a RAM disk).
These are only for when the OS and the machine itself can't deal with the extra memory and wouldn't know what to do with it, things you buy when you run out of sensible options (such as adding more memory to your machine and/or configuring a RAM disk).