[Simh] Memories are made of this ...

[dave porter]

>From: Johnny Billquist <bqt at softjar.se>
>And an even stronger curmudgeon warning here then.

According to the terminology I (another curmudgeon) grew
up on and still use, you're conflating virtual addressing and
virtual memory.

Virtual addressing is where each job/task/process/etc gets
its own address space. This can be implemented by something
as simple as datum and limit registers.  The benefits include
mutual protection and the ability to link independently of
the eventual load address.

(i.e., the addresses are virtualized, the addressed storage
  is not)

Virtual memory is where not all of a virtual address space
is necessarily backed by storage directly addressable by
the processor, at any given point in time. The benefits
include more efficient use of physical memory and the
ability (given enough address bits) to have an address
space exceeding physical limits, without burdening the
app programmer with managing the migration.

(i.e., the addressed storage is itself virtualized)