AW: AW: When did Memory- and IO Protection Emerge (Esp. in Minis)?

[Toby Thain]

On 2016-05-05 2:55 PM, Gottfried Specht wrote:
> Thanks, Erik.
>
> How do I remember this ca. 40 years later?
>
> Well, while servicing these systems they would frequently stop with a "Memory Protect Error" (various Operating Systems).
>
> Guess what the intuitive action was: Replace the "Memory Protect Board" - which  n e v e r  fixed the problem.
>
> So digging into the technology it became clear, that the Memory Protect Board in these cases had only fulfilled its duty: protect the memory below the fence register from some other piece of hardware (usually a processor or DMA-board) running havoc in memory. That learning stuck ...


Well, at least the directive wasn't "remove the Memory Protect board"? :-)

--Toby


>
> Kind regards,
> Gottfried
> _____
> Gottfried Specht | Gottfried at specht-online.com |  +49 211 151695+49 151 2911 2915
>
> -----Ursprüngliche Nachricht-----
> Von: cctalk [mailto:cctalk-bounces at classiccmp.org] Im Auftrag von Erik Baigar
> Gesendet: Donnerstag, 5. Mai 2016 10:36
> An: General Discussion: On-Topic and Off-Topic Posts
> Betreff: Re: AW: When did Memory- and IO Protection Emerge (Esp. in Minis)?
>
>
>
> On Wed, 4 May 2016, Gottfried Specht wrote:
>
>> I'm not sure whether it qualifies for your full list, but the HP2100A
>> (that came out in 1971) had a "Memory Protect" hardware that
> ...