“640K ought to be enough for anybody,” Bill Gates famously once said, referring to RAM in PCs. Or at least he’s rumored to have said—the man himself strenuously denies the attribution and a number of sources who have worked to trace the provenance of the comment have come up short. That said, as this slideshow demonstrates, 640 KB was a stupendous amount of memory for the time. Take a look back at some of the early technologies used for digital data storage—and realize that it would probably take dozens of them to deliver the same capacity as in your average car key.
Memory and disk space will both expand to overflow existing technology. At the time Bill made his statement, few of us had ever used more than 64K bytes of memory. It was only after memory prices fell that the great explosion began.
I remember when 8K by 16 bits cost $1/bit. Compare that to today's costs and you can see why Bill assumed the growth of memory would be limited.
By the way, I have a 16K by 16 bit ferrite bead board framed in my living room as an example of the past example of memory technology.