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Re: z/PDOS-generic

From John Ames <commodorejohn@gmail.com>
Newsgroups alt.os.development
Subject Re: z/PDOS-generic
Date 2025-03-11 12:41 -0700
Organization A noiseless patient Spider
Message-ID <20250311124158.0000716c@gmail.com> (permalink)
References <v7bbdt$2fj5a$1@dont-email.me> <20250310151114.000023e9@gmail.com> <vqnrjl$4a9$1@reader1.panix.com> <20250311083745.000076a4@gmail.com> <vqprsc$25q$1@reader1.panix.com>

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On Tue, 11 Mar 2025 17:28:44 -0000 (UTC)
cross@spitfire.i.gajendra.net (Dan Cross) wrote:

> Getting back to the specific example of MS-DOS, it does provide
> both, but does Not provide a way to e.g., multiplex IO and
> computation temporally; so performing a disk operation will
> just block the program until the operation completes.  Don't
> want that?  Go touch the hardware yourself.  The control program
> doesn't really help me here.

I mean, asynchronous I/O is certainly a nicety, but why does not having
it make an OS not "real?"

> In a lot of ways, the ABI is irrelevant for workaday
> programming: you leave it up to a tool, or a system library, or
> something like that, but you rarely have to think about it.  The
> issue with the DOS API is that it is defined _solely_ in terms
> of the hardware interface, and moreover it is highly specific to
> that hardware.
> 
> So while you could "name" those things and not just number them,
> the things themselves are still very tightly coupled to the
> hardware.  Those aren't great abstractions.

So an OS that is specifically tied to a particular architecture and
uses specific sequences of instructions is "not a real OS?" Funny, you
never hear that against ITS.

> It's interesting that there was a port of Unix to the XT that
> was, of course, subject to the same limitations.  Sometimes you
> are just constrained, so you make due with what you have.  But
> Unix at least used the segmentation facilities in the processor
> to _attempt_ to shield the kernel from errant user processes;
> DOS made no such attempt.

Absent any means of hardware protection, "segmentation" on the part of
the OS is a gentle suggestion at best; it cannot even protect against
an *errant* process, let alone a malicious one. DOS also uses the
segmented model to allocate space to applications/drivers/etc., but
pretending that this actually impedes hazardous behavior is just empty
security theater.

> Not true.  It supported segmentation.  It's harder to corrupt
> RAM if it's not in a segment that's currently addressible.

Again *there is no protection.* None whatsoever. Altering the segment
registers is a non-privileged operation on the 8086, and the address-
translation mechanism is a simple shift-and-add; it is trivial for any
process to write to any part of memory, whatever its initial segment-
register values were.

> And when the 286 came out, MS-DOS didn't grow to use it, even
> though it was there.  Nor did they try to incorporate larger
> segments or virtual memory when the 386 came out.

MS and IBM did in fact try to extend DOS using the capabilities of 286
protected mode, under both Windows/286 and OS/1 v.1. Neither worked
well or saw wide adoption, because the 286 was terrible. By the time
the 386 was gaining significant acceptance, MS was already moving on to
Windows NT, which eventually did offer protected (if limited) DOS
support via NTVDM.

> Now my question to you: why do you care what specific label
> people apply to MS-DOS?

Primarily because Certain Types insist on parroting the same pithy
dismissals over and over again, year after year after year, for no
readily apparent reason and despite their arguments being predicated on
nonintuitive definitions of common terms, which are in the best case
overly narrow and, in the least charitable interpretation, pretty
clearly constructed to support the argument they wanted to make.

Now, in fairness to yourself, Scott is the one who's really been
tossing cherry bombs in the toilet here, and I think you're catching
some flak that really ought to go his way; but you *also* are insistent
on defining common terms in such a way as to exclude things that pretty
much anybody without a partisan stake wouldn't hesitate to count in
with the group - it's not enough, apparently, to say that MS-DOS is a
*simplistic* OS, or even *not a particularly good one,* but that it's
somehow not *really* an OS at all, even though you yourself admit that
it does fundamentally fill the role of one:

> So it's hard to see how DOS really qualifies as an OS, despite
> the OS-like abstractions it provides.

So why the semantic games? What is the actual *point* to this argument?

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Thread

z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-07-18 23:07 +0800
  Re: z/PDOS-generic Grant Taylor <gtaylor@tnetconsulting.net> - 2024-07-18 22:40 -0500
    Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-07-19 18:43 +0800
      Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2024-07-19 16:18 +0000
        Re: z/PDOS-generic BGB-Alt <bohannonindustriesllc@gmail.com> - 2024-07-19 17:12 -0500
          Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2024-07-19 23:21 +0000
            Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2024-07-19 23:31 +0000
            Re: z/PDOS-generic BGB <cr88192@gmail.com> - 2024-07-20 01:30 -0500
            Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2024-07-22 07:51 -0700
              Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2024-07-22 15:22 +0000
                Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2024-07-22 09:07 -0700
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2024-07-22 17:37 +0000
                Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2024-07-22 18:07 +0000
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2024-07-22 19:38 +0000
                Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2024-07-22 11:18 -0700
              Re: z/PDOS-generic BGB <cr88192@gmail.com> - 2024-07-22 14:16 -0500
                Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2024-07-22 20:14 +0000
                Re: z/PDOS-generic BGB <cr88192@gmail.com> - 2024-07-22 18:03 -0500
                Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2024-07-22 23:58 +0000
                Re: z/PDOS-generic BGB <cr88192@gmail.com> - 2024-07-22 23:06 -0500
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-08-21 04:31 +0800
                Re: z/PDOS-generic BGB <cr88192@gmail.com> - 2024-08-28 02:28 -0500
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-08-28 16:54 +0800
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-08-28 16:58 +0800
                Re: z/PDOS-generic BGB <cr88192@gmail.com> - 2024-08-28 18:03 -0500
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-08-29 11:14 +0800
                Re: z/PDOS-generic George Neuner <gneuner2@comcast.net> - 2024-08-30 06:49 -0400
                Re: z/PDOS-generic George Neuner <gneuner2@comcast.net> - 2024-08-30 10:27 -0400
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-08-31 10:21 +0800
                Re: z/PDOS-generic George Neuner <gneuner2@comcast.net> - 2024-08-31 15:30 -0400
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2024-09-03 14:27 +0000
                Re: z/PDOS-generic wolfgang kern <nowhere@never.at> - 2024-08-30 13:29 +0200
          Re: z/PDOS-generic Waldek Hebisch <antispam@fricas.org> - 2024-09-03 23:38 +0000
            Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-09-06 07:46 +0800
              Re: z/PDOS-generic J. Curtis <unknown@protocol.invalid> - 2024-09-06 20:08 +0100
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-09-07 08:12 +0800
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-01-22 17:34 +1100
        Re: z/PDOS-generic J. Curtis <unknown@protocol.invalid> - 2024-07-20 00:02 +0100
        Re: z/PDOS-generic Salvador Mirzo <smirzo@example.com> - 2025-03-08 14:42 -0300
          Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-09 02:09 +0000
            Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2025-03-09 15:40 +0000
              Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-10 12:38 +0000
                Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2025-03-10 14:49 +0000
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-10 15:00 +0000
            Re: z/PDOS-generic Salvador Mirzo <smirzo@example.com> - 2025-03-10 09:21 -0300
              Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-10 13:50 +0000
                Re: z/PDOS-generic Salvador Mirzo <smirzo@example.com> - 2025-03-10 14:10 -0300
                Studying the system (was Re: z/PDOS-generic) cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-10 18:29 +0000
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-11 05:38 +1100
                Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2025-03-10 19:07 +0000
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-10 19:09 +0000
                Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2025-03-10 13:00 -0700
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-10 20:20 +0000
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-11 07:59 +1100
                Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2025-03-10 15:11 -0700
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-10 23:11 +0000
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-11 10:51 +1100
                Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2025-03-11 08:37 -0700
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-11 17:28 +0000
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-12 05:40 +1100
                Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2025-03-11 12:41 -0700
                What is an operating system? (was Re: z/PDOS-generic) cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-11 21:00 +0000
                Re: What is an operating system? (was Re: z/PDOS-generic) "Paul Edwards" <mutazilah@gmail.com> - 2025-03-12 17:30 +1100
                Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2025-03-11 09:04 -0700
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-11 08:29 +1100
            Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-11 05:06 +1100
              Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2025-03-10 19:01 +0000
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-11 08:04 +1100
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-11 08:47 +1100
            Re: z/PDOS-generic antispam@fricas.org (Waldek Hebisch) - 2025-03-11 18:15 +0000
              Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-11 18:29 +0000
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-12 05:52 +1100
                Re: z/PDOS-generic antispam@fricas.org (Waldek Hebisch) - 2025-03-11 23:05 +0000
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-11 23:48 +0000
                Re: z/PDOS-generic antispam@fricas.org (Waldek Hebisch) - 2025-03-12 02:23 +0000
                Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-12 02:34 +0000
                Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2025-03-12 18:41 +1100
      Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2024-07-19 09:35 -0700
        Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-08-21 04:20 +0800
          Re: z/PDOS-generic John Ames <commodorejohn@gmail.com> - 2024-08-21 09:51 -0700
            Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-08-22 13:24 +0800
      Re: z/PDOS-generic Grant Taylor <gtaylor@tnetconsulting.net> - 2024-07-19 19:46 -0500
        Re: z/PDOS-generic "Paul Edwards" <mutazilah@gmail.com> - 2024-08-21 04:18 +0800
    Re: z/PDOS-generic Salvador Mirzo <smirzo@example.com> - 2025-03-08 14:41 -0300
      Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-09 01:58 +0000
        Re: z/PDOS-generic Salvador Mirzo <smirzo@example.com> - 2025-03-10 09:31 -0300
          Re: z/PDOS-generic cross@spitfire.i.gajendra.net (Dan Cross) - 2025-03-10 14:28 +0000
          Re: z/PDOS-generic scott@slp53.sl.home (Scott Lurndal) - 2025-03-10 14:46 +0000

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