:really off topic but I so rarely can add to the discussions.

Actually in order to address memory out of the address range of the cpu bus a "page swap" method was used which had been used on mainframes for many years, this was called expanded memory and was in 16k chunks which was very slow. with the 286 line extended memory was introduced and the cpu had to go into extended mode in order to access it. That of course if my memory serves me.