Re: [COFF] [TUHS] Memory management in Dennis Ritchie's C Compiler - COFF

18 Aug 2020

--> COFF

Paul Winalski &lt;paul.winalski(a)gmail.com&gt; wrote:

mmap() / $CRETVA

...
  The VMS image activator (runtime loader in Unix-speak)
used these
 primitives to load program images into virtual memory.  More than one
 process can map the same region of a file.  This is how sharing of
 read-only program segments such as .text is implemented.

 I think Burroughs OSes had this concept even before VMS. 
Did MULTICS work the same way?

The Manchester / Ferranti Atlas had virtual memory in 1962 but I don't
know how much they used it for multiprogramming (and by implication shared
text segments) - it didn't do timesharing until later, but AIUI virtual
memory helped it to have an exceptionally good job throughput for the
time. Perhaps their motivation was more to do with having a good shared
implementation of overlays and paged IO.

https://en.wikipedia.org/wiki/Single-level_store

Tony.
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