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

    From Peter Flass@3:633/10 to All on Sun Nov 2 12:57:51 2025
    On 3/25/10 03:02, Nick Keighley wrote:
    On 24 Mar, 23:40, Phil Carmody <thefatphil_demun...@yahoo.co.uk>
    wrote:
    Dann Corbit <dcor...@connx.com> writes:
    In article <1e27d5ee-a1b1-45d9-9188-
    63ab37398...@d37g2000yqn.googlegroups.com>,
    nick_keighley_nos...@hotmail.com says...

    On 23 Mar, 20:56, glen herrmannsfeldt <g...@ugcs.caltech.edu> wrote:
    In alt.sys.pdp10 Richard Bos <ralt...@xs4all.nl> wrote:
    (snip)

    That crossposting was, for once, not asinine. It served as a nice
    example why, even now, Leenux weenies are not correct when they insist >>>>>> that C has a flat memory model and all pointers are just numbers.

    Well, you could also read the C standard to learn that.

    but if you say that you get accused of language lawyering.
    "Since IBM stopped making 360s no C program ever needs to run on such
    a platform"

    We have customers who are running their business on harware from the mid >>> 1980s. ˙It may sound ludicrous, but it if solves all of their business
    needs, and runs solid 24x365, why should they upgrade?

    Because they could run an equivalently computationally powerful
    solution with various levels of redundancy and fail-over protection,
    with a power budget sensibly measured in mere Watts?

    does it have a Coral compiler?

    There's a market for someone.

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Peter Flass@3:633/10 to All on Sun Nov 2 13:08:25 2025
    On 3/23/10 13:56, glen herrmannsfeldt wrote:
    In alt.sys.pdp10 Richard Bos <raltbos@xs4all.nl> wrote:
    (snip)

    That crossposting was, for once, not asinine. It served as a nice
    example why, even now, Leenux weenies are not correct when they insist
    that C has a flat memory model and all pointers are just numbers.


    This is true often enough to be dangerous when it turns out not to be.

    Well, you could also read the C standard to learn that.

    There are additional complications for C on the PDP-10.

    -- glen


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Peter Flass@3:633/10 to All on Sun Nov 2 13:13:20 2025
    On 3/31/10 13:30, Jonathan de Boyne Pollard wrote:


    As has been said here many times, different languages have different
    problem domains.˙ Most of the trouble people have is caused by using
    the wrong language for what they're trying to do.˙ It used to be
    Fortran or COBOL, now, apparently, it's stuff like Java.

    The attraction of Java is obvious; you can hire cheap inexperienced
    unskilled individuals to crank out Java code.

    Typically, a fair amount of a programming class washes out when you
    get to teaching pointers and structures.˙ Some wash out even earlier
    on recursion.˙ These individuals were lost to employers, who had to
    spend a great deal more on skilled individuals who could understand
    such things.

    Java fixed that.˙ Thanks to Java, any snot-nosed kid can write
    Important Applications.

    They just won't be very robust applications.

    The fact that I've heard exactly the same argument made about Visual
    BASIC, ten years ago, casts heavy doubt on the fact that it's Java that
    is to blame for all of the world's ills.


    Some people claim that for Excel.

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Peter Flass@3:633/10 to All on Sun Nov 2 13:20:14 2025
    What happened here?? I just noticed that a lot of these posts are from
    2010. Did some news server just barf?

    On 3/23/10 14:42, Peter Flass wrote:
    Branimir Maksimovic wrote:
    On Tue, 23 Mar 2010 06:51:18 -0400
    Peter Flass <Peter_Flass@Yahoo.com> wrote:

    Jonathan de Boyne Pollard wrote:
    Returning to what we were talking about before the silly diversion,
    I should point out that 32-bit applications programming where the
    target is extended DOS or 32-bit Win16 (with OpenWatcom's extender)
    will also occasionally employ 16:32 far pointers of course.˙ But as
    I said before, regular 32-bit OS/2 or Win32 applications
    programming generally does not, since those both use the Tiny
    memory model,
    Flat memory model.

    Problem with standard C and C++ is that they assume flat memory
    model.

    I'm not a C expert, perhaps you're a denizen of comp.lang.c, but as far
    as I know there's nothing in the C standard that assumes anything about pointers, except that they have to be the same size as int, so for 16:32 pointers I guess you'd need 64-bit ints.

    As far as implementations are concerned, both Watcom and IBM VA C++
    support segmented memory models.˙ These are the ones I'm aware of, there
    are probably more.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Charlie Gibbs@3:633/10 to All on Mon Nov 3 00:12:24 2025
    On 2025-11-02, Peter Flass <Peter@Iron-Spring.com> wrote:

    On 3/31/10 13:30, Jonathan de Boyne Pollard wrote:


    As has been said here many times, different languages have different
    problem domains.˙ Most of the trouble people have is caused by using
    the wrong language for what they're trying to do.˙ It used to be
    Fortran or COBOL, now, apparently, it's stuff like Java.

    The attraction of Java is obvious; you can hire cheap inexperienced
    unskilled individuals to crank out Java code.

    Typically, a fair amount of a programming class washes out when you
    get to teaching pointers and structures.˙ Some wash out even earlier
    on recursion.˙ These individuals were lost to employers, who had to
    spend a great deal more on skilled individuals who could understand
    such things.

    Java fixed that.˙ Thanks to Java, any snot-nosed kid can write
    Important Applications.

    They just won't be very robust applications.

    The fact that I've heard exactly the same argument made about Visual
    BASIC, ten years ago, casts heavy doubt on the fact that it's Java that
    is to blame for all of the world's ills.

    Some people claim that for Excel.

    I see what you're saying - the language is merely the vehicle of the
    day for the bad attitudes of those programming in it. However, Excel
    has its own warts regardless of user programs; I've spent far too much
    time Excel-proofing my CSV files so that Excel doesn't mess with them. Fortunately, Excel doesn't seem to recognize ISO 8601 as a date format; otherwise it tries to enforce the dictum that all dates shall be in
    dd/mm/yy format, and will mangle anything it thinks is a date in a
    sensible format like yyyy/mm/dd. And then it has the effrontery to
    ask you on exit: "Would you like to save the changes you've made?"
    Grrr...

    --
    /~\ Charlie Gibbs | Growth for the sake of
    \ / <cgibbs@kltpzyxm.invalid> | growth is the ideology
    X I'm really at ac.dekanfrus | of the cancer cell.
    / \ if you read it the right way. | -- Edward Abbey

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Charlie Gibbs@3:633/10 to All on Mon Nov 3 00:14:22 2025
    On 2025-11-03, Charlie Gibbs <cgibbs@kltpzyxm.invalid> wrote:

    otherwise it tries to enforce the dictum that all dates shall be in
    dd/mm/yy format,

    My bad. I meant mm/dd/yy, of course. Here in Canada there's
    no telling which one you're going to be faced with.

    --
    /~\ Charlie Gibbs | Growth for the sake of
    \ / <cgibbs@kltpzyxm.invalid> | growth is the ideology
    X I'm really at ac.dekanfrus | of the cancer cell.
    / \ if you read it the right way. | -- Edward Abbey

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Lynn McGuire@3:633/10 to All on Mon Nov 3 14:24:27 2025
    On 11/2/2025 2:20 PM, Peter Flass wrote:
    What happened here?? I just noticed that a lot of these posts are from
    2010. Did some news server just barf?

    On 3/23/10 14:42, Peter Flass wrote:
    Branimir Maksimovic wrote:
    On Tue, 23 Mar 2010 06:51:18 -0400
    Peter Flass <Peter_Flass@Yahoo.com> wrote:

    Jonathan de Boyne Pollard wrote:
    Returning to what we were talking about before the silly diversion,
    I should point out that 32-bit applications programming where the
    target is extended DOS or 32-bit Win16 (with OpenWatcom's extender)
    will also occasionally employ 16:32 far pointers of course.˙ But as
    I said before, regular 32-bit OS/2 or Win32 applications
    programming generally does not, since those both use the Tiny
    memory model,
    Flat memory model.

    Problem with standard C and C++ is that they assume flat memory
    model.

    I'm not a C expert, perhaps you're a denizen of comp.lang.c, but as
    far as I know there's nothing in the C standard that assumes anything
    about pointers, except that they have to be the same size as int, so
    for 16:32 pointers I guess you'd need 64-bit ints.

    As far as implementations are concerned, both Watcom and IBM VA C++
    support segmented memory models.˙ These are the ones I'm aware of,
    there are probably more.

    I asked Ray Banana of E-S about the openwatcom.* groups and he
    resurrected them with all of their very old postings.

    Lynn


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Peter Flass@3:633/10 to All on Mon Nov 3 16:25:06 2025
    On 11/3/25 13:24, Lynn McGuire wrote:
    On 11/2/2025 2:20 PM, Peter Flass wrote:
    What happened here?? I just noticed that a lot of these posts are from
    2010. Did some news server just barf?

    On 3/23/10 14:42, Peter Flass wrote:
    Branimir Maksimovic wrote:
    On Tue, 23 Mar 2010 06:51:18 -0400
    Peter Flass <Peter_Flass@Yahoo.com> wrote:

    Jonathan de Boyne Pollard wrote:
    Returning to what we were talking about before the silly diversion, >>>>>> I should point out that 32-bit applications programming where the
    target is extended DOS or 32-bit Win16 (with OpenWatcom's extender) >>>>>> will also occasionally employ 16:32 far pointers of course.˙ But as >>>>>> I said before, regular 32-bit OS/2 or Win32 applications
    programming generally does not, since those both use the Tiny
    memory model,
    Flat memory model.

    Problem with standard C and C++ is that they assume flat memory
    model.

    I'm not a C expert, perhaps you're a denizen of comp.lang.c, but as
    far as I know there's nothing in the C standard that assumes anything
    about pointers, except that they have to be the same size as int, so
    for 16:32 pointers I guess you'd need 64-bit ints.

    As far as implementations are concerned, both Watcom and IBM VA C++
    support segmented memory models.˙ These are the ones I'm aware of,
    there are probably more.

    I asked Ray Banana of E-S about the openwatcom.* groups and he
    resurrected them with all of their very old postings.

    Lynn


    Oh, OK. Also everything that was X-posted. No worries.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Kaz Kylheku@3:633/10 to All on Tue Nov 4 00:26:40 2025
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    Amazing ...

    --
    TXR Programming Language: http://nongnu.org/txr
    Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
    Mastodon: @Kazinator@mstdn.ca

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Scott Lurndal@3:633/10 to All on Tue Nov 4 15:20:41 2025
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Paul S Person@3:633/10 to All on Tue Nov 4 08:29:21 2025
    On Tue, 4 Nov 2025 00:26:40 -0000 (UTC), Kaz Kylheku
    <643-408-1753@kylheku.com> wrote:

    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    Amazing ...

    I'm not sure about today, but that late there were still people
    programming on older hardware for various specialized purposes. Or
    rather, I suppose, maintaining the code. (I would say "devices" but
    that now implies "something that runs Apps" and these were much much
    older).

    One of the advantages of Watcom (and so OpenWatcom) has always been
    support for 16-bit programming. Of course, whether that is true today
    is hard to say.
    --
    "Here lies the Tuscan poet Aretino,
    Who evil spoke of everyone but God,
    Giving as his excuse, 'I never knew him.'"

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Paul S Person@3:633/10 to All on Tue Nov 4 08:32:47 2025
    On Mon, 3 Nov 2025 14:24:27 -0600, Lynn McGuire
    <lynnmcguire5@gmail.com> wrote:

    On 11/2/2025 2:20 PM, Peter Flass wrote:
    What happened here?? I just noticed that a lot of these posts are from

    2010. Did some news server just barf?

    <snippo>

    I asked Ray Banana of E-S about the openwatcom.* groups and he
    resurrected them with all of their very old postings.

    I tested the OpenWatcom Usenet server, and Agent reported no response.

    So the groups still exist (and, I suspect, not just on E-S), but not
    at the source.
    --
    "Here lies the Tuscan poet Aretino,
    Who evil spoke of everyone but God,
    Giving as his excuse, 'I never knew him.'"

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Peter Flass@3:633/10 to All on Tue Nov 4 09:39:41 2025
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today? Most
    disguise segmentation as a flat address space (e.g. IBM System/370 et.seq.)

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Richard Heathfield@3:633/10 to All on Tue Nov 4 17:12:46 2025
    On 04/11/2025 15:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.

    I can still hear them down the hall.

    ST!
    .......................................................Amiga!
    ST!
    .......................................................Amiga!

    --
    Richard Heathfield
    Email: rjh at cpax dot org dot uk
    "Usenet is a strange place" - dmr 29 July 1999
    Sig line 4 vacant - apply within

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Scott Lurndal@3:633/10 to All on Tue Nov 4 17:14:01 2025
    Peter Flass <Peter@Iron-Spring.com> writes:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today?

    Only in emulation (see Unisys Clearpath, for example).

    Most
    disguise segmentation as a flat address space (e.g. IBM System/370 et.seq.)

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From geodandw@3:633/10 to All on Tue Nov 4 12:15:27 2025
    On 11/4/25 12:12, Richard Heathfield wrote:
    On 04/11/2025 15:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.

    I can still hear them down the hall.

    ST!
    .......................................................Amiga!
    ST!
    .......................................................Amiga!

    The 68000 was a very nice processor for its time. It's too bad IBM
    didn't use it in the PC.

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Kaz Kylheku@3:633/10 to All on Tue Nov 4 17:21:31 2025
    On 2025-11-04, geodandw <geodandw@gmail.com> wrote:
    The 68000 was a very nice processor for its time. It's too bad IBM
    didn't use it in the PC.

    That would have been so much better even if it still had had a shitty
    CP/M-like OS with drive letter names and whatnot.

    --
    TXR Programming Language: http://nongnu.org/txr
    Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
    Mastodon: @Kazinator@mstdn.ca

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Scott Lurndal@3:633/10 to All on Tue Nov 4 17:32:24 2025
    scott@slp53.sl.home (Scott Lurndal) writes:
    Peter Flass <Peter@Iron-Spring.com> writes:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today?

    Only in emulation (see Unisys Clearpath, for example).

    Although it's worth pointing out that harvard architectures
    still exist (e.g. CEVA DSPs) and the low-power ARM
    M-series core 32-bit physical address space is
    divided into 28-bit regions some of which may
    provide programmable windows into alternate address spaces
    in a fashion very similar to segmentation.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Kaz Kylheku@3:633/10 to All on Tue Nov 4 17:38:28 2025
    On 2025-11-04, Scott Lurndal <scott@slp53.sl.home> wrote:
    scott@slp53.sl.home (Scott Lurndal) writes:
    Peter Flass <Peter@Iron-Spring.com> writes:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)? >>>>
    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today?

    Only in emulation (see Unisys Clearpath, for example).

    Although it's worth pointing out that harvard architectures
    still exist (e.g. CEVA DSPs) and the low-power ARM

    Ah, that. I worked with the TeakLite III.

    In addition to the hardvard thing, I remember its smallest addressable
    is was 16 bits, From the host processor (ARM) in that SoC, it appeared
    to have "funny endian": 32 bit words written by the TeakLite appeared
    in 2143 order or something, not 1234 or 4321.

    --
    TXR Programming Language: http://nongnu.org/txr
    Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
    Mastodon: @Kazinator@mstdn.ca

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From David Brown@3:633/10 to All on Tue Nov 4 21:23:44 2025
    On 04/11/2025 18:32, Scott Lurndal wrote:
    scott@slp53.sl.home (Scott Lurndal) writes:
    Peter Flass <Peter@Iron-Spring.com> writes:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)? >>>>
    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today?

    Only in emulation (see Unisys Clearpath, for example).

    Although it's worth pointing out that harvard architectures
    still exist (e.g. CEVA DSPs)

    Yes, but Harvard architectures are a very different matter from
    segmented architectures. "Real" Harvard architecture processors have different instructions for accessing different memory spaces - such as
    on the AVR microcontrollers, the instructions for reading ram and
    reading program flash are totally different, and you cannot execute code
    from ram.

    Segmented architecture just means that the actual address is formed by a scaled segment register (or value) combined with an offset or pointer
    register (or value).

    There are plenty of segmented architectures in the world of small microcontrollers, where the "pointer" might be 8-bit, 16-bit, or a pair
    of 8-bit registers, and it is combined with a bank or segment register
    so that the device can use more than 64KB memory. These devices may or
    may not be Harvard. Fortunately, most of these are considered legacy
    devices.

    and the low-power ARM
    M-series core 32-bit physical address space is
    divided into 28-bit regions some of which may
    provide programmable windows into alternate address spaces
    in a fashion very similar to segmentation.


    All the ARM Cortex-M cores have 32-bit linear memory spaces. There is
    no segmentation. Different parts of the memory space are used for
    different purposes (ram, flash, peripherals, off-chip memory, etc.), and
    there can be lots of different memory-mapped devices placed at different points in the memory spaces. But all access is via 32-bit addresses in
    32-bit registers, without any segmentation registers. (And I have never
    seen a Cortex-M device with programmable windows or addresses - indeed,
    I believe the Cortex-M core documentation specifies some memory ranges explicitly. Memory protection units can be programmable to give
    different accesses, writes and cachability attributes to different
    regions, but that's another matter.)




    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Scott Lurndal@3:633/10 to All on Tue Nov 4 22:04:43 2025
    David Brown <david.brown@hesbynett.no> writes:
    On 04/11/2025 18:32, Scott Lurndal wrote:

    . (And I have never
    seen a Cortex-M device with programmable windows or addresses - indeed,
    I believe the Cortex-M core documentation specifies some memory ranges >explicitly.

    I have used Cortex-M devices with programmable windows
    in the physical address space.

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Lawrence D?Oliveiro@3:633/10 to All on Tue Nov 4 22:17:44 2025
    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.

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Lawrence D?Oliveiro@3:633/10 to All on Tue Nov 4 22:19:17 2025
    On Tue, 4 Nov 2025 12:15:27 -0500, geodandw wrote:

    The 68000 was a very nice processor for its time. It's too bad IBM
    didn't use it in the PC.

    Might have been a cost issue (more pins, more cost).

    In any case, the 680x0 family was very popular among Unix workstation
    vendors, until it was completely eclipsed in performance by the coming of RISC.

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Nuno Silva@3:633/10 to All on Tue Nov 4 23:26:23 2025
    On 2025-11-04, Scott Lurndal wrote:

    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.

    Now that's silly, if anything it'd be Slot 1 processors that are better
    than sliced bread.

    (Although heatsinks and fans can make these quite volumous slices.)

    --
    Nuno Silva

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From David Brown@3:633/10 to All on Wed Nov 5 08:50:25 2025
    On 04/11/2025 23:04, Scott Lurndal wrote:
    David Brown <david.brown@hesbynett.no> writes:
    On 04/11/2025 18:32, Scott Lurndal wrote:

    . (And I have never
    seen a Cortex-M device with programmable windows or addresses - indeed,
    I believe the Cortex-M core documentation specifies some memory ranges
    explicitly.

    I have used Cortex-M devices with programmable windows
    in the physical address space.

    OK. I have not, but I haven't used the newer Cortex-M cores as yet, so
    it could well be a new feature. It could also be an option which the mainstream microcontroller manufacturers don't provide. Which ones have programmable windows? And is this something that will be common, or is
    it just something that a few manufacturers with "architect" (if that is
    the right term) ARM licenses implement on their own?

    (I know this is off-topic for c.l.c., but I'm interested in there devices.)


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Scott Lurndal@3:633/10 to All on Wed Nov 5 15:15:14 2025
    David Brown <david.brown@hesbynett.no> writes:
    On 04/11/2025 23:04, Scott Lurndal wrote:
    David Brown <david.brown@hesbynett.no> writes:
    On 04/11/2025 18:32, Scott Lurndal wrote:

    . (And I have never
    seen a Cortex-M device with programmable windows or addresses - indeed,
    I believe the Cortex-M core documentation specifies some memory ranges
    explicitly.

    I have used Cortex-M devices with programmable windows
    in the physical address space.

    OK. I have not, but I haven't used the newer Cortex-M cores as yet, so
    it could well be a new feature.

    It is not necessarily a feature of the M7 core itself, but rather
    the glue logic around it - particularly the logic that interfaces
    to the "system bus" to which the M7 core is interfaced. That logic
    is under the control of the SoC designer and can easily have
    external registers that are programmed to specify how to route
    accesses from the M7, including to large regions of DRAM;
    consider a maintenance processor on a 64-bit server that needs
    access to the server DRAM space for RAS purposes.



    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From David Brown@3:633/10 to All on Thu Nov 6 08:51:37 2025
    On 05/11/2025 16:15, Scott Lurndal wrote:
    David Brown <david.brown@hesbynett.no> writes:
    On 04/11/2025 23:04, Scott Lurndal wrote:
    David Brown <david.brown@hesbynett.no> writes:
    On 04/11/2025 18:32, Scott Lurndal wrote:

    . (And I have never
    seen a Cortex-M device with programmable windows or addresses - indeed, >>>> I believe the Cortex-M core documentation specifies some memory ranges >>>> explicitly.

    I have used Cortex-M devices with programmable windows
    in the physical address space.

    OK. I have not, but I haven't used the newer Cortex-M cores as yet, so
    it could well be a new feature.

    It is not necessarily a feature of the M7 core itself, but rather
    the glue logic around it - particularly the logic that interfaces
    to the "system bus" to which the M7 core is interfaced. That logic
    is under the control of the SoC designer and can easily have
    external registers that are programmed to specify how to route
    accesses from the M7, including to large regions of DRAM;
    consider a maintenance processor on a 64-bit server that needs
    access to the server DRAM space for RAS purposes.


    Fair enough, now I see what you are getting at. Yes, once you are
    outside the Cortex-M core and key ARM-supplied components (like the
    interrupt controller), you as a SoC designer are free to do what you
    like. And if you have a 32-bit processor that needs access to a 64-bit address space, you are going to have to do some kind of windowing or segmenting.

    In the SoC's I have used where 64-bit Cortex-A processors are combined
    with a Cortex-M core for security purposes, booting, or for better
    real-time control of peripherals, the Cortex-M device does not have
    direct access to the 64-bit memory space. It has access to the
    peripherals, some dedicated memory, and a message-passing interface with
    the Cortex-A cores.

    But in your work, you probably see more variety and more possibilities
    for these things - I only get to use the chips someone else has made!


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Dan Cross@3:633/10 to All on Fri Nov 7 15:50:53 2025
    In article <10eda8d$3pd45$1@dont-email.me>,
    Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today? Most
    disguise segmentation as a flat address space (e.g. IBM System/370 et.seq.)

    x86_64 is still nominally segmented; what "code segment" the
    processor is running in matters, even in long mode. But most of
    the segment data is ignored by hardware (e.g., base and limits)
    in 64-bit mode.

    Of course, it retains a notion of segmentation for a) 16- and
    32-bit code compatibility, and b) startup, where the processor
    (still!!) comes out of reset in 16-bit real mode.

    Intel had a proposal to do away with 16-bit mode and anything
    other than long mode for 64-bit, but it seems to have died. So
    it seems like we'll be stuck with x86 segmentation --- at least
    for compatibility purposes --- for a while longer still.

    - Dan C.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Scott Lurndal@3:633/10 to All on Fri Nov 7 16:08:54 2025
    cross@spitfire.i.gajendra.net (Dan Cross) writes:
    In article <10eda8d$3pd45$1@dont-email.me>,
    Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today? Most
    disguise segmentation as a flat address space (e.g. IBM System/370 et.seq.)

    x86_64 is still nominally segmented; what "code segment" the
    processor is running in matters, even in long mode. But most of
    the segment data is ignored by hardware (e.g., base and limits)
    in 64-bit mode.

    Minor correction, an update to AMD64 was done back in
    the oughts to support some segment limit registers for 64-bit XEN
    (and probably for vmware as well).

    See the LMSLE bit in the EFER register for more details.

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Paul S Person@3:633/10 to All on Fri Nov 7 08:22:11 2025
    On Fri, 7 Nov 2025 15:50:53 -0000 (UTC), cross@spitfire.i.gajendra.net
    (Dan Cross) wrote:

    In article <10eda8d$3pd45$1@dont-email.me>,
    Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32
    bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today? Most
    disguise segmentation as a flat address space (e.g. IBM System/370
    et.seq.)

    x86_64 is still nominally segmented; what "code segment" the
    processor is running in matters, even in long mode. But most of
    the segment data is ignored by hardware (e.g., base and limits)
    in 64-bit mode.

    Of course, it retains a notion of segmentation for a) 16- and
    32-bit code compatibility, and b) startup, where the processor
    (still!!) comes out of reset in 16-bit real mode.

    Intel had a proposal to do away with 16-bit mode and anything
    other than long mode for 64-bit, but it seems to have died. So
    it seems like we'll be stuck with x86 segmentation --- at least
    for compatibility purposes --- for a while longer still.

    This is all very interesting as a summary of where-we-are. Thanks.

    Didn't Intel, at one time, plan to replace all xxx8x processors with
    one of the new! shiny! RISC processor?

    Only to be defeated when it was pointed out that a whole lot of
    software would have to run on it. Software written for their xxx8x
    processors, segmentation and all.
    --
    "Here lies the Tuscan poet Aretino,
    Who evil spoke of everyone but God,
    Giving as his excuse, 'I never knew him.'"

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Dan Cross@3:633/10 to All on Fri Nov 7 16:46:56 2025
    In article <10edcbg$lrh1$1@dont-email.me>,
    geodandw <geodandw@gmail.com> wrote:
    On 11/4/25 12:12, Richard Heathfield wrote:
    On 04/11/2025 15:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.

    I can still hear them down the hall.

    ST!
    .......................................................Amiga!
    ST!
    .......................................................Amiga!

    The 68000 was a very nice processor for its time. It's too bad IBM
    didn't use it in the PC.

    They wanted to. IBM had a close relationship with Motorola, and
    they even had engineering samples in Westchester. The problem
    was that 68k was a skunkworks project inside of Moto, which was
    pushing the 6809 as the Next Big Thing. So when IBM was talking
    to Moto sales about using 68k for the PC, Moto was pushing them
    (not so gently) towards the 6809 and telling them 68k was just a
    research project with no future.

    IBM was smart enough to know that the 6809 was going to be a
    non-starter (a firmly 8-bit micro when 16-bit CPUs were becoming
    mainstream), and the 8088 met their specs for the 5150, so they
    went with Intel instead. By the time it was clear that the 68k
    was going to be Moto's flagship CPU going forward, it was too
    late for inclusion in the PC.

    And here we are.

    - Dan C.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Dan Cross@3:633/10 to All on Fri Nov 7 16:54:44 2025
    In article <qQoPQ.1134549$p8E9.400952@fx18.iad>,
    Scott Lurndal <slp53@pacbell.net> wrote:
    cross@spitfire.i.gajendra.net (Dan Cross) writes:
    In article <10eda8d$3pd45$1@dont-email.me>,
    Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)? >>>>
    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today? Most >>>disguise segmentation as a flat address space (e.g. IBM System/370 et.seq.) >>
    x86_64 is still nominally segmented; what "code segment" the
    processor is running in matters, even in long mode. But most of
    the segment data is ignored by hardware (e.g., base and limits)
    in 64-bit mode.

    Minor correction, an update to AMD64 was done back in
    the oughts to support some segment limit registers for 64-bit XEN
    (and probably for vmware as well).

    See the LMSLE bit in the EFER register for more details.

    Interesting. AMD-only, not Intel.

    This is why we can't have nice things.

    - Dan C.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Dan Cross@3:633/10 to All on Fri Nov 7 17:22:51 2025
    In article <7r6sgktd4p0ae1e3p97hc7h89nloaldbrj@4ax.com>,
    Paul S Person <psperson@old.netcom.invalid> wrote:
    On Fri, 7 Nov 2025 15:50:53 -0000 (UTC), cross@spitfire.i.gajendra.net
    (Dan Cross) wrote:

    In article <10eda8d$3pd45$1@dont-email.me>,
    Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)? >>>>
    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today? Most >>>disguise segmentation as a flat address space (e.g. IBM System/370 et.seq.) >>
    x86_64 is still nominally segmented; what "code segment" the
    processor is running in matters, even in long mode. But most of
    the segment data is ignored by hardware (e.g., base and limits)
    in 64-bit mode.

    Of course, it retains a notion of segmentation for a) 16- and
    32-bit code compatibility, and b) startup, where the processor
    (still!!) comes out of reset in 16-bit real mode.

    Intel had a proposal to do away with 16-bit mode and anything
    other than long mode for 64-bit, but it seems to have died. So
    it seems like we'll be stuck with x86 segmentation --- at least
    for compatibility purposes --- for a while longer still.

    This is all very interesting as a summary of where-we-are. Thanks.

    Didn't Intel, at one time, plan to replace all xxx8x processors with
    one of the new! shiny! RISC processor?

    Well, Itanium was going to sweep all that came before it into
    the dustbin of history.

    Only to be defeated when it was pointed out that a whole lot of
    software would have to run on it. Software written for their xxx8x >processors, segmentation and all.

    Nah, that wasn't that big of an issue. By then, segmentation
    was already mostly legacy and systems that really relied on it
    had been designed in an era of slow CPUs that could be emulated
    in software if you really needed them for installed base
    compatibility.

    The heyday of x86 segmentation was really over by 1985. The
    80386 was intended to be a processor for the Unix workstation
    market, and supported a paged, flat 32-bit address space. They
    shoehorned that into the segmented model by a) increasing the
    size of the segment limit and b) adding the "granularity" bit in
    segment descriptors that allowed segments to be defined in units
    of 4KiB, rather than single bytes. The upshot was that a
    segment could cover the full 32-bit virtual address space; so
    the intended use case was that OSes would set up a couple 4GiB
    segments at boot, point the segmentation registers at those, and
    then work in terms of the paged virtual address space after
    that; all of the nasty pre-386 segment stuff would be relegated
    to a relatively small part of the system. So most software that
    really used the segmentation stuff had been written for the 286
    or earlier, when CPUs were pretty slow and pokey, making
    emulation a reasonable path for backwards compatibility.

    The bigger problem for Itanium was that, in order to really
    perform well, they needed super-smart compilers that could do
    the instruction scheduling needed to take advantage of its VLIW
    architecture. Those never came, and so the realized performance
    just wasn't there relative to the promises Intel had made for
    the architecture. Meanwhile, a bunch of ex-DEC people went to
    AMD and did the AMD64 extensions for x86, which a) performed
    pretty decently (at a much lower price-point than Itanium), and
    b) was directly backwards compatible with 32-bit x86. Within,
    what, a year or so, Intel had no choice but to copy the design
    with their own offering, and the market ran with it.

    This was all in the last 90s/early 2000s, but by 2003 or there
    abouts it was clear that Itanium was never going to reach its
    promises.

    Speculating about alternate historical timelines is always fun.
    Had IBM chosen the 68k two decades before Itanium, I suspect the
    world would be very different: Moto didn't try to push that
    design beyond the 68060, which was competitive with the Pentium
    at roughly the same time, but didn't have a pipelined FPU;
    perhaps it would if Moto had had the kind of capital resources
    Intel could bring to bear for Pentium and beyond. I suspect,
    however, that Moto would have dumped the 68k architecture and
    we'd all be using some kind of RISC ISA directly.

    One final note about Itanium: Intel had tried the VLIW thing
    before with the i860, and ran into the same problem: the
    compilers of that era just weren't there to make it competitive
    for general-purpose compute. You'd think they'd have learned
    that lesson for Itanium, and either done the compiler work
    themselves, or funded it externally, _before_ betting so big on
    it.

    - Dan C.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Scott Lurndal@3:633/10 to All on Fri Nov 7 17:43:25 2025
    Paul S Person <psperson@old.netcom.invalid> writes:
    On Fri, 7 Nov 2025 15:50:53 -0000 (UTC), cross@spitfire.i.gajendra.net
    (Dan Cross) wrote:

    Intel had a proposal to do away with 16-bit mode and anything
    other than long mode for 64-bit, but it seems to have died. So
    it seems like we'll be stuck with x86 segmentation --- at least
    for compatibility purposes --- for a while longer still.

    This is all very interesting as a summary of where-we-are. Thanks.

    Dan was referring to https://www.intel.com/content/www/us/en/developer/articles/technical/envisioning-future-simplified-architecture.html


    Didn't Intel, at one time, plan to replace all xxx8x processors with
    one of the new! shiny! RISC processor?

    The EPIC[*] processor family (Monterey, Merced) known now as Itanium
    was intended to be Intel's replacement for the x86 server grade
    processors, replacing the proposed P7[**] design. It was an epic failure, primarily due to cost, compiler complexity and lack of competitive performance.

    [*] Explicitly Parallel Instruction Computing.

    [**] Which was a RISC-like processor. Unfortunately, there's not much
    information about the original P7 design on the internet, and I
    wasn't allowed to keep my P7 orange books.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Lawrence D?Oliveiro@3:633/10 to All on Fri Nov 7 19:40:56 2025
    On Fri, 07 Nov 2025 08:22:11 -0800, Paul S Person wrote:

    Didn't Intel, at one time, plan to replace all xxx8x processors with
    one of the new! shiny! RISC processor?

    They tried twice, and failed both times. The first time was the i860 <https://www.youtube.com/watch?v=WTkFGZqVCM8>.

    The second, better-known failure was in conjunction with HP <https://www.youtube.com/watch?v=3oxrybkd7Mo>.

    Only to be defeated when it was pointed out that a whole lot of
    software would have to run on it. Software written for their xxx8x processors, segmentation and all.

    In terms of software compatibility, open-source platforms like Linux
    have shown that that does not need to be a barrier to innovation at
    all.

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Peter Flass@3:633/10 to All on Sat Nov 8 08:45:04 2025
    On 11/7/25 08:50, Dan Cross wrote:
    In article <10eda8d$3pd45$1@dont-email.me>,
    Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/4/25 08:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)?

    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.


    I was thinking, are there any segmented architectures today? Most
    disguise segmentation as a flat address space (e.g. IBM System/370 et.seq.)

    x86_64 is still nominally segmented; what "code segment" the
    processor is running in matters, even in long mode. But most of
    the segment data is ignored by hardware (e.g., base and limits)
    in 64-bit mode.

    Of course, it retains a notion of segmentation for a) 16- and
    32-bit code compatibility, and b) startup, where the processor
    (still!!) comes out of reset in 16-bit real mode.

    Intel had a proposal to do away with 16-bit mode and anything
    other than long mode for 64-bit, but it seems to have died. So
    it seems like we'll be stuck with x86 segmentation --- at least
    for compatibility purposes --- for a while longer still.

    - Dan C.


    Probably at least until the 128-bit systems arrive ;-)

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Peter Flass@3:633/10 to All on Sat Nov 8 08:47:11 2025
    On 11/7/25 09:46, Dan Cross wrote:
    In article <10edcbg$lrh1$1@dont-email.me>,
    geodandw <geodandw@gmail.com> wrote:
    On 11/4/25 12:12, Richard Heathfield wrote:
    On 04/11/2025 15:20, Scott Lurndal wrote:
    Kaz Kylheku <643-408-1753@kylheku.com> writes:
    On 2025-11-03, Peter Flass <Peter@Iron-Spring.com> wrote:
    On 11/3/25 13:24, Lynn McGuire wrote:

    When I saw this subject line, I thought it was some necroposting to
    threads from 1990.

    Someone still cared about segmented x86 shit in 2010 (even if 32 bit)? >>>>
    There are still people on the internet who swear that the 286 is
    better than sliced bread and refuse to recognize that modern
    architectures are superior.

    I can still hear them down the hall.

    ST!
    .......................................................Amiga!
    ST!
    .......................................................Amiga!

    The 68000 was a very nice processor for its time. It's too bad IBM
    didn't use it in the PC.

    They wanted to. IBM had a close relationship with Motorola, and
    they even had engineering samples in Westchester. The problem
    was that 68k was a skunkworks project inside of Moto, which was
    pushing the 6809 as the Next Big Thing. So when IBM was talking
    to Moto sales about using 68k for the PC, Moto was pushing them
    (not so gently) towards the 6809 and telling them 68k was just a
    research project with no future.

    IBM was smart enough to know that the 6809 was going to be a
    non-starter (a firmly 8-bit micro when 16-bit CPUs were becoming
    mainstream), and the 8088 met their specs for the 5150, so they
    went with Intel instead. By the time it was clear that the 68k
    was going to be Moto's flagship CPU going forward, it was too
    late for inclusion in the PC.

    And here we are.

    - Dan C.


    I think they used the 680x0 in one of their small computers. Maybe the "Laboratory Computer"?

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From John Levine@3:633/10 to All on Sat Nov 8 21:17:05 2025
    According to Peter Flass <Peter@Iron-Spring.com>:
    I think they used the 680x0 in one of their small computers. Maybe the >"Laboratory Computer"?

    That was IBM Instruments, a small company that IBM bought after they'd
    already developed the product and just rebadged it.


    --
    Regards,
    John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
    Please consider the environment before reading this e-mail. https://jl.ly

    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Michael S@3:633/10 to All on Sun Nov 9 11:15:01 2025
    On Fri, 7 Nov 2025 17:22:51 -0000 (UTC)
    cross@spitfire.i.gajendra.net (Dan Cross) wrote:

    the architecture. Meanwhile, a bunch of ex-DEC people went to
    AMD and did the AMD64 extensions for x86, which a) performed

    Do you have a proof that it was done by Ex-DEC people?
    My impression is that Ex-DEC people, esp. Jim Keller, were very
    important as micro-architects of K7 and K8, but I don't remember ever
    reading that they played major role in the stage of architectural
    definitions of AMD64.



    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Dan Cross@3:633/10 to All on Mon Nov 10 09:08:58 2025
    In article <20251109111501.00000fcd@yahoo.com>,
    Michael S <already5chosen@yahoo.com> wrote:
    On Fri, 7 Nov 2025 17:22:51 -0000 (UTC)
    cross@spitfire.i.gajendra.net (Dan Cross) wrote:

    the architecture. Meanwhile, a bunch of ex-DEC people went to
    AMD and did the AMD64 extensions for x86, which a) performed

    Do you have a proof that it was done by Ex-DEC people?
    My impression is that Ex-DEC people, esp. Jim Keller, were very
    important as micro-architects of K7 and K8, but I don't remember ever
    reading that they played major role in the stage of architectural
    definitions of AMD64.

    I'm afraid I do not. I may be incorrect on that part,
    or misattributing IP transfer from the cross-licensing
    agreement that came out of thr DEC/Intel lawsuit to
    sprcific engineers.

    - Dan C.


    --- PyGate Linux v1.5
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)