19 Aug
2020
19 Aug
'20
5:48 a.m.
--> COFF
Paul Winalski <paul.winalski(a)gmail.com> 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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