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Re: 16:32 far pointers in OpenWatcom C/C++

From Lawrence D’Oliveiro <ldo@nz.invalid>
Newsgroups alt.folklore.computers, openwatcom.users.c_cpp, comp.lang.c
Subject Re: 16:32 far pointers in OpenWatcom C/C++
Date 2025-11-04 22:17 +0000
Organization A noiseless patient Spider
Message-ID <10edu28$3vith$2@dont-email.me> (permalink)
References (9 earlier) <10eb31q$34thk$7@dont-email.me> <10ebdki$387ml$1@dont-email.me> <20251103162451.184@kylheku.com> <dRoOQ.1421028$xYr1.1123604@fx14.iad> <10eda8d$3pd45$1@dont-email.me>

Cross-posted to 3 groups.

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On Tue, 4 Nov 2025 09:39:41 -0700, Peter Flass wrote:

> I was thinking, are there any segmented architectures today?

Two different meanings of segmentation. It is possible to use segmentation 
in a flat address space, as a memory-management technique. Think paging, 
but with variable-length pages. (E.g. Burroughs machines did this. Also 
think of how program code on the old 680x0-based Macintosh machines could 
be divided up into individually-swappable “CODE” segments.)

The trouble was, such a scheme was prone to fragmentation, where the total 
free memory might be larger than the segment you want to load, but it’s 
broken up into discontiguous pieces that are too small to use. This is why 
paging was preferred instead.

But now, with 64-bit architectures commonplace, you have multi-level page 
tables. Think of these as a form of segmentation, where each segment is 
made up of whole pages.

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Thread

Re: 16:32 far pointers in OpenWatcom C/C++ Peter Flass <Peter@Iron-Spring.com> - 2025-11-02 13:20 -0700
  OT: 2010 posts (was: Re: 16:32 far pointers in OpenWatcom C/C++) Nuno Silva <nunojsilva@invalid.invalid> - 2025-11-03 14:58 +0000
  Re: 16:32 far pointers in OpenWatcom C/C++ Lynn McGuire <lynnmcguire5@gmail.com> - 2025-11-03 14:24 -0600
    Re: 16:32 far pointers in OpenWatcom C/C++ Peter Flass <Peter@Iron-Spring.com> - 2025-11-03 16:25 -0700
      Re: 16:32 far pointers in OpenWatcom C/C++ Kaz Kylheku <643-408-1753@kylheku.com> - 2025-11-04 00:26 +0000
        Re: 16:32 far pointers in OpenWatcom C/C++ scott@slp53.sl.home (Scott Lurndal) - 2025-11-04 15:20 +0000
          Re: 16:32 far pointers in OpenWatcom C/C++ Peter Flass <Peter@Iron-Spring.com> - 2025-11-04 09:39 -0700
            Re: 16:32 far pointers in OpenWatcom C/C++ scott@slp53.sl.home (Scott Lurndal) - 2025-11-04 17:14 +0000
              Re: 16:32 far pointers in OpenWatcom C/C++ scott@slp53.sl.home (Scott Lurndal) - 2025-11-04 17:32 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ Kaz Kylheku <643-408-1753@kylheku.com> - 2025-11-04 17:38 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ David Brown <david.brown@hesbynett.no> - 2025-11-04 21:23 +0100
                Re: 16:32 far pointers in OpenWatcom C/C++ scott@slp53.sl.home (Scott Lurndal) - 2025-11-04 22:04 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ David Brown <david.brown@hesbynett.no> - 2025-11-05 08:50 +0100
                Re: 16:32 far pointers in OpenWatcom C/C++ scott@slp53.sl.home (Scott Lurndal) - 2025-11-05 15:15 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ David Brown <david.brown@hesbynett.no> - 2025-11-06 08:51 +0100
            Re: 16:32 far pointers in OpenWatcom C/C++ Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-04 22:17 +0000
            Re: 16:32 far pointers in OpenWatcom C/C++ cross@spitfire.i.gajendra.net (Dan Cross) - 2025-11-07 15:50 +0000
              Re: 16:32 far pointers in OpenWatcom C/C++ scott@slp53.sl.home (Scott Lurndal) - 2025-11-07 16:08 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ cross@spitfire.i.gajendra.net (Dan Cross) - 2025-11-07 16:54 +0000
              Re: 16:32 far pointers in OpenWatcom C/C++ Paul S Person <psperson@old.netcom.invalid> - 2025-11-07 08:22 -0800
                Re: 16:32 far pointers in OpenWatcom C/C++ cross@spitfire.i.gajendra.net (Dan Cross) - 2025-11-07 17:22 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ Michael S <already5chosen@yahoo.com> - 2025-11-09 11:15 +0200
                Re: 16:32 far pointers in OpenWatcom C/C++ cross@spitfire.i.gajendra.net (Dan Cross) - 2025-11-10 09:08 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ scott@slp53.sl.home (Scott Lurndal) - 2025-11-07 17:43 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-07 19:40 +0000
              Re: 16:32 far pointers in OpenWatcom C/C++ Peter Flass <Peter@Iron-Spring.com> - 2025-11-08 08:45 -0700
          Re: 16:32 far pointers in OpenWatcom C/C++ Richard Heathfield <rjh@cpax.org.uk> - 2025-11-04 17:12 +0000
            Re: 16:32 far pointers in OpenWatcom C/C++ geodandw <geodandw@gmail.com> - 2025-11-04 12:15 -0500
              Re: 16:32 far pointers in OpenWatcom C/C++ Kaz Kylheku <643-408-1753@kylheku.com> - 2025-11-04 17:21 +0000
              Re: 16:32 far pointers in OpenWatcom C/C++ Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-04 22:19 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ rbowman <bowman@montana.com> - 2025-11-05 00:13 +0000
              Re: 16:32 far pointers in OpenWatcom C/C++ cross@spitfire.i.gajendra.net (Dan Cross) - 2025-11-07 16:46 +0000
                Re: 16:32 far pointers in OpenWatcom C/C++ Peter Flass <Peter@Iron-Spring.com> - 2025-11-08 08:47 -0700
                Re: 16:32 far pointers in OpenWatcom C/C++ John Levine <johnl@taugh.com> - 2025-11-08 21:17 +0000
        Re: 16:32 far pointers in OpenWatcom C/C++ Paul S Person <psperson@old.netcom.invalid> - 2025-11-04 08:29 -0800
    Re: 16:32 far pointers in OpenWatcom C/C++ Paul S Person <psperson@old.netcom.invalid> - 2025-11-04 08:32 -0800

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