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 ... Kind regards, Gottfried _____ Gottfried Specht | gottfr...@specht-online.com | +49 211 151695+49 151 2911 2915 -----Ursprüngliche Nachricht----- Von: cctalk [mailto:cctalk-boun...@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 Hi Gottfried, thanks for the excellent answer - yes I think this is exactly what matches my specification! Thanks. It is really astonishing how many people know a lot on various machines which is really great. I suspected that HP had something, too. > Fence Register: Set under program control; memory below fence is protected. This is a clever and somewhat outstanding feature - most others use protection on basis of blocks ar abuse the virtual memory for the purpose ;-) Best regards, Erik. > -----Ursprüngliche Nachricht----- > Von: cctalk [mailto:cctalk-boun...@classiccmp.org] Im Auftrag von Erik > Baigar > Gesendet: Dienstag, 3. Mai 2016 17:53 > An: cctalk@classiccmp.org > Betreff: When did Memory- and IO Protection Emerge (Esp. in Minis)? > > > Dear Experts, > > during discussing the Rolms I came accross the following question: > What was the first (Minicomputer) architecture which offered > memory- and IO protection? I'd define the minimum requirements as: > > - Existence of a superuser mode (Rolm calls this Executive mode) > - Existence of a user mode (With at least two users, Rolm offers 4) > - In superuser mode, IO and memory protection for each user can be > set up individually. > - Any access violation is trapped and handeled by superuser code. > - Of course commands for mode switching and setting up the > memory and IO ranges must exist. > > I have got a real machine (Rolm 1602) having this implemented and dating from > 1975. A document on this "Access Protection Module" as Rolm calls it also is > dated 1975. It consists of a microcode module which realizes an extension of > the 16 bit Nova instruction set and an additinoal CPU module, taking care of > the new modes and supervising the IO- and memory accesses. > > My question is not regarding virtual memory memory, but regarding protection > (IO and memory) to ensure capsulation of indivitual processes - not > necessarily for multi user environments but e.g. > for safety critical applications... > > Probably OS/2 in 1987 was one of the first home computer OSes to support > memory protection (how about IO protection?), BSD on some Digital PDP-* was > earlier (1977?) but still after the 1602. > > Any hints out there on other "Mini" architectures of that era having someting > similar? > > Erik. >
