4 ms·

well sort of, similar stuff ... though it's worth remembering that Burroughs security depends on only specially blessed programs called 'compilers' being able t

well sort of, similar stuff ... though it's worth remembering that Burroughs security depends on only specially blessed programs called 'compilers' being able to make code - because the underlying architecture has no real protection, it depends on compiled code playing well with the hardware. There are all these special hardware descriptors and stuff so that you can't step out of arrays, but there's also an instruction you can execute that will blindly make one (and there's one available to every process that describes all of memory ....). As I said system integrity and system security depends on people not being able to make arbitrary code, only a privileged user can make code a compiler, and only a compiler can make a code file .... The 432 had a lot of similar data structures but genuinely did have the security and integrity one would expect from a capability system

Joker_vD 4y ago
Sounds like Midori/Singularity. Or like any of Per Brinch Hansen's OSes, written in concurrent dialects of Pascal and depending on the language-level constructs for memory protection and process separation (they could and did run on machines without MMUs).
- Taniwha 4y ago
  The old Burroughs systems (up to at least the B7700) didn't really have MMUs in the traditional sense - their descriptors only reserved 20 bits for (word addresses) so they were limited to ~6Mb of addressing - not a big deal when we had paid over a US$ million for 1.5Mb of B6700 core, no one could have afforded more - they paged segments (much as a 432 would have) and also supported segments chunked into 256 word chunks for large arrays (at the cost of an extra memory access per lookup).