Re: Partial Hardware Protection for Buffer Overrun Exploits

[Ed Falis <falis@adelphia.net>]

On 22 Apr 2003 17:15:09 -0400
Robert A Duff <bobduff@shell01.TheWorld.com> wrote:

> The 80186 did not support protected mode.  It was practically
> identical in architecture to an 8086 or 8088.  The 80186 had a small
> number of additional instructions -- e.g., pushall for pushing all
> registers, I think (for some definition of "all").

It also had bank-switching of memory, but that doesn't quite qualify as
"protected mode".

> 
> It was used in mainly in embedded systems, I believe.
> 
> >... and the 80286 chips that powered the IBM PC/AT. These early chips
> > supported a command for transitioning from real to protected mode,
> > but no simple command for transitioning back to real mode. This is
> > what earned these chips the "brain dead" assessment from Gates. 

Yeah, but that brain-dead design actually allowed the first Ada compiler
on a PC. ;-)

- Ed