On Saturday 18 August 2001 15:50, Calin Culianu wrote:
> On Fri, 17 Aug 2001, David Olofson wrote:
[...]
> > If the pointers would really be different, it's entirely possible
> > that they one type can't be translated into the other, and possibly
> > vice versa. (Think about near and far pointers; one can be converted
> > into the other, but not the other way around - copying the buffer is
> > the only way.)
>
> Actually, maybe I am too young to know this, but what is a far pointer?
> Is this a concept used with segmented memory schemes?
Yes.
Intel CPUs can actually still use 16:16 and 16:32 addresses, although
most modern operating systems set the selector part (same registers as
used for the segment part of Real Mode addresses) to fixed values. Then
they play around with the memory mapping tables instead, allowing all
normal code to reach all accessible memory within a linear 4 GB address
space. (That is, you never have to pass the full 16+32 bit "far" address;
the 32 bits of the "short" pointer are always enough.)
//David Olofson --- Programmer, Reologica Instruments AB
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