RE: IBM loses its Unix license - Jun. 16, 2003

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

> Oh how I hate to nit-pick, but there's nothing to watch on TV, so
> sorry Joe...
>
> There was memory protection in all commercial versions of Windows
> (3.0, 3.1 and 3.11 aka; Windows for Workgroups). If you ever got
> a GPF message box when running applications, there was the memory
> protection mechanism coming into play - GPF remember, was the TLA
> for General Protection Fault.

That ain't how I rememebr it, Phil.

A GPF meant: "13 (0Dh): General Protection Fault - Any condition that is not
covered by any of the other processor exceptions will result in a general
protection fault. The exception indicates that this program has been
corrupted in memory, usually resulting in immediate termination of the
program."

The problem is that one process could CAUSE a GPF in another process simply
by messing with a pointer.  Nothing stopped you from wiping out entire other
processes with buffer overruns or bad array indexes.  OS/2 eliminated this
problem by making sure programs could not access each other's memory.  This
is one of the basic tenets of solid multi-tasking architecture (and one,
incidentally, that the single level store design actually weakens, but I'd
rather not dance that dance tonight).

Joe