In message c80uf8l09l11obigasfro8oj622tlfu9od@None, at 14:14:20 on
Tue, 22 Jan 2013, Robert Neville remarked:
Something to add to the list of:

"There will never be more than 256 networks on the Internet"

and "640K ought to be enough for anybody."

I almost wrote that, but it's not quite the same.

The 1MB limit on the PC as a whole was because of addressing issues in
the processor, so is really Intel saying "no-one will ever need more
than 1MB".

After that, IBM decided on an architecture that split the 1MB up into
the motherboard and peripherals (where in this case the BIOS, whose
primary job was controlling peripherals, broadly counts as peripheral
memory). That split was 640k/384k [5+3 blocks of 128k], with video RAM
nailed in from 640K upwards and main BIOS from 928k upwards.

After many years, when it became clear that 640k of motherboard RAM
wasn't going to be enough it is alleged that Bill Gates gave the quote
above (but actual cites are thin on the ground), but the reason was
because he didn't (yet) have an OS that would usefully exploit either
the holes between 640k and 1MB, nor the 64k above 1MB that some bright
spark discovered was accessible due to an unforeseen quirk of the
processor chip.
--
Roland Perry