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From: Tom Van Vleck <thvv@multicians.org>
Newsgroups: alt.folklore.computers,alt.os.multics
Subject: Re: Multics addressing [Re: command line switches [Re: [REALLY OT!] Overuse of symbolic constants]]
Organization: Multicians
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 Peter Flass wrote:
> Morten Reistad wrote:
> > Shareble code come in several flavours. 
> > 
> > TOPS10 (and 20), Primos SEG code, MP/M libraries and ISTR some multics
> > share mode just link pure code into some reserved address space
> > ("high" segments om many OS'es) , and make up a .rel/.a file with
> > mocked-up jumps to this address space.  Some system administrator must
> > assign the addresses, and make some magic incantations to make the
> > code load at the right address space when needed. If you run out of
> > address space you are lost, likewise if someone fouls up the magic, or
> > if you need two libraries at conflicting address areas.
> 
> I believe *every* Multics program was sharable; one program=one segment. 
>   The OS loaded the segment, copied the program's template linkage 
> segment onto the end of the process's linkage segment, and there you 
> were.  The only limitation was the number of segments allowed by the 
> hardware. No administration needed.

Correct.  The hardware segmentation support allowed us to 
map a single page table as different segment numbers in 
different processes.  Any object file produced by a 
compiler could be used as a library with no additional 
processing.  All compilers produced pure code. Libraries 
required no relocation when loading.