Re: z/PDOS-generic

From	cross@spitfire.i.gajendra.net (Dan Cross)
Newsgroups	alt.os.development
Subject	Re: z/PDOS-generic
Date	2025-03-10 23:11 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<vqnrjl$4a9$1@reader1.panix.com> (permalink)
References	<v7bbdt$2fj5a$1@dont-email.me> <20250310130006.00000497@gmail.com> <vqnhhi$atq$1@reader1.panix.com> <20250310151114.000023e9@gmail.com>

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In article <20250310151114.000023e9@gmail.com>,
John Ames  <commodorejohn@gmail.com> wrote:
>On Mon, 10 Mar 2025 20:20:02 -0000 (UTC)
>cross@spitfire.i.gajendra.net (Dan Cross) wrote:
>
>> But I do know a lot about operating systems, and the objections
>> to categorizing things like MS-DOS as "a *real* OS" are not mere
>> handwaving that boils down to "Because Reasons"; there are
>> actual definitions in use across the field one can look to, and
>> MS-DOS et al simply do not meet them.  It's great that control
>> software in the early PC era let people do useful work with
>> those machines; that doesn't mean that software was good or fit
>> reasonable definitions of what an "Operating System" is.
>
>So let's dig into that a bit. Merriam-Webster defines an "operating
>system" thusly: 
>
>> software that controls the operation of a computer and directs the
>> processing of programs (as by assigning storage space in memory and
>> controlling input and output functions)

Msrs. Merriam and Webster were not, to my knowledge, computer
scientists.

>Wikipedia, being edited by Wikipedians, is a little more weird and
>obtuse, but more or less in accord:
>
>> Software that is designed for controlling the allocation and the use
>> of various hardware resources to tasks and remote terminals.

Indeed obtuse.  What about a system that does not use "remote
terminals"?

I already posted the definition I like to use, which came to me
via Mothy Roscoe, at ETH, but I'll post it again:

He defines the operating system as,
That body of software that,
1. Multiplexes the machine's hardware resources
2. Abstracts the hardware platform
3. Protects software principles from each other
   (using the hardware)

I further posted how I feel that MS-DOS dos not meet these
criteria, and why.

So arguing about a definiton from a mass-market English langauge
dictionary and/or wikipedia is not, frankly, very compelling in
comparison.

>MS-DOS very definitely takes control of the computer - it does not
>*hold onto it* very tightly, but there's no particular reason it should
>have to.

Given the above definition, there's a very good reason: how does
it otherwise protect _itself_, as a software principle, from an
errant, let alone malicious, program?

Also, a boot loader takes control of the computer, albeit
temporarily: is that also an operating system?  Merely taking
control of the computer is insufficient.  The OpenBoot PROM
monitor on a SPARCstation could be entered via a keyboard
shortcut, suspending Unix and the SPARC processor; was that an
"operating system"?  I don't think anyone working on it thought
of it that way.

>In a single-tasking, single-user environment any operation the
>user invokes can be Considered Legitimate, and this loose approach to
>protection makes it possible for third-party or user-written software to
>hook into interrupts/API calls and extend the system easily (although
>DOS users generally made less use of this than classic MacOS users did.)

While an operation a *user* invokes, such as running a command
or invoking a program, can be "Considered Legitimate" in that
context, it does not follow every operation performed by a
program is legitimate.  Programs have bugs; those bugs can
corrupt the state of the system; at best this may simply crash
the system.  At worst it can lead to data corruption or loss.

DOS can't protect against that.  So it fails criteria (3) of
Roscoe's definition.

>It also manages memory allocation (enabling applications, drivers, and
>TSRs to co-exist safely, provided they behave themselves) and handles

Actually, it did not allow TSRs to "co-exist" safely, because
the set of things required to do so goes far beyond mere memory
allocation.  Since you brought up Wikipedia, the article on TSRs
that Scott linked to earlier went into this in detail, and is
well worth reading.

>input and output to/from screen/keyboard, disk, and parallel and serial
>ports. Again, it does not *prevent* programs from taking control of
>these things themselves, but that's a trade-off - yes, you lose some
>security,* assuming you even care about that, but you gain flexibility.
>(Supporting new hardware is generally as simple as writing a program to
>frob the appropriate ports, unless the OS needs to be able to treat it
>as a standard storage/communications channel. Even then, hooking into
>the necessary interrupts is fairly straightforward.)
>
>* (And it's worth noting that, in the original PC architecture pre-286,
>  it's functionally impossible to do protection anyway. There's not a
>  damn thing *any* OS running on an 8086 can do to prevent an errant
>  program from scribbling over the OS/another process or frobbing an
>  I/O port something else is trying to manage.)

See above.

	- Dan C.

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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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