Virtual vs Physical memory (was Re: Designing around a 6502)

From: Ethan Dicks <erd_6502_at_yahoo.com>
Date: Tue Feb 11 14:42:00 2003

--- Sean 'Captain Napalm' Conner <spc_at_conman.org> wrote:
> It was thus said that the Great Hans Franke once stated:
> >
> > (*1) Often the term real memory is used, but that's
> > not correct. Physical memory is the memory installed
> > in a machine, while real address space is the addressable
> > amount of RAM by a CPU without using virtual addressing.
> > Virtual address space can never excede real address space
> > (After all, it's the maximum address range generated by
> > the (logical) CPU), while physical memory can go beyond
> > real or virual address space.
>
> Virtual address space *can* exceed physical address space---the 80386
> (and therefore, on topic) is a good example.


And typically does (VAX-11/750 - 14MB physical max, 4GB virtual space),
but not always (PDP-11 - 4MB physical max, 64KB process space, described
in the literature as virtual space since the CPU has 16-bit address
registers)

> A segmented architecture...

I have one word to say about segmented architecture... "Ewwwww"

-ethan
Received on Tue Feb 11 2003 - 14:42:00 GMT