Re: Instruction And Data memory

In article <d6labs$gs7$1@xxxxxxxxxxxxxxxxxxxxxxxxx>, anno4000
@lublin.zrz.tu-berlin.de says...
> Keith Williams <krw@xxxxxxxxxx> wrote in sci.electronics.design:
> > In article <d6kg3n$spo$1@xxxxxxxxxxxxxxxxxxxxxxxxx>, anno4000
> > @lublin.zrz.tu-berlin.de says...
> > > PeteS <ps@xxxxxxxxxxxxxxxxxxx> wrote in sci.electronics.design:
>
> [instruction memory vs. data memory]
>
> > > I'd make explicit that there is no technical difference between
> > > instruction memory and data memory, in case that was what the
> > > intent of the OP's question. They are the same kind of RAM since
> > > drum storage was scrapped. Any differences in behavior are by design,
> > > not by the nature of one or the other.
> >
> > Not necessarily. Instruction memory can be quite different than data
> > memory in a Harvard Architecture processor.
>
> Ah, okay...
>
> > > Instruction memory runs with von Neumann's blessings, data memory
> > > doesn't.
> >
> > Not on purpose anyway. ;-)
>
> It is a strange, if off-topic, observation that von Neumann made modern
> computing possible by bridging the gap between instructions and data,
> but modern computing does everything to make them as clearly distinct
> as possible.

Yes, indeed. AMD introduced the No-Execute bit in the page table on
x86 processors to further segregate data and memory.

> It must, to stay sane (Lisp-programmers excluded :)

Sure, Lisp programmers are excluded from those trying to stay sane.
;-)

--
Keith
.

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