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Atari mini-clone

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  Atari mini-clone "Paul Edwards" <mutazilah@gmail.com> - 2025-06-09 16:52 +1000
    Re: Atari mini-clone "Kerr-Mudd, John" <admin@127.0.0.1> - 2025-06-09 17:13 +0100
      Re: Atari mini-clone cross@spitfire.i.gajendra.net (Dan Cross) - 2025-06-09 18:22 +0000

#18802 — Atari mini-clone

PDOS-generic was invented in an Amiga forum and allowed
proof of concept of a mini Amiga clone.

But it was considered impossible to do the same thing for the
Atari because the Atari used traps.

Same as MSDOS used interrupts and MVS uses SVCs.

But in an Atari forum, a method was invented to allow
traps to be converted into callbacks.

This is totally obvious in hindsight, but it wasn't obvious
in the beginning.

Using this technique, an Atari mini-clone has been created,
and the executables can be found at the last message here:

https://atari-forum.com/viewtopic.php?t=43832

This can be run on any Linux system using qemu-m68k (user, not system).

Or you could replace the pseudobios and run it on an Amiga
(ie use the Amiga to emulate Atari - a subset of Atari executables -
ones (code for "just mine") that follow the new "A1 standard").

Note that this runs at full native speed (68000), and does not
require privilege (that's a general comment - I don't think
the 68000 has privilege). Basically you don't need to install
a trap handler. The application is expected to cooperate and
not call a trap unnecessarily.

BFN. Paul.

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#18803

On Mon, 9 Jun 2025 16:52:06 +1000
"Paul Edwards" <mutazilah@gmail.com> wrote:

> PDOS-generic was invented in an Amiga forum and allowed
> proof of concept of a mini Amiga clone.
> 
> But it was considered impossible to do the same thing for the
> Atari because the Atari used traps.
> 
> Same as MSDOS used interrupts and MVS uses SVCs.
> 
> But in an Atari forum, a method was invented to allow
> traps to be converted into callbacks.
> 
> This is totally obvious in hindsight, but it wasn't obvious
> in the beginning.
> 
> Using this technique, an Atari mini-clone has been created,
> and the executables can be found at the last message here:
> 
> https://atari-forum.com/viewtopic.php?t=43832
> 
> This can be run on any Linux system using qemu-m68k (user, not system).
> 
> Or you could replace the pseudobios and run it on an Amiga
> (ie use the Amiga to emulate Atari - a subset of Atari executables -
> ones (code for "just mine") that follow the new "A1 standard").
> 
> Note that this runs at full native speed (68000), and does not
> require privilege (that's a general comment - I don't think
> the 68000 has privilege). Basically you don't need to install
> a trap handler. The application is expected to cooperate and
> not call a trap unnecessarily.
> 
Not my kind of retro-computing background, but well done!

-- 
Bah, and indeed Humbug.

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#18804

In article <20250609171359.1e72687dfd0b829f1fb62aa5@127.0.0.1>,
Kerr-Mudd, John <admin@127.0.0.1> wrote:
>On Mon, 9 Jun 2025 16:52:06 +1000
>"Paul Edwards" <mutazilah@gmail.com> wrote:
>> Note that this runs at full native speed (68000), and does not
>> require privilege (that's a general comment - I don't think
>> the 68000 has privilege). Basically you don't need to install
>> a trap handler. The application is expected to cooperate and
>> not call a trap unnecessarily.
> 
>Not my kind of retro-computing background, but well done!

It's shocking how ignorant some people are.  68000 absolutely
has supervisor mode.  That said, please don't feed the troll.

	- Dan C.

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