MMU support

[ma693541]

Now that the PeeZee's we use for UAE/WinUAE emulating are getting faster with more CPU power and Dual/Quad core support. Isn't it time we get a MMU support for our 040/060 emulated Amiga's soon?

[OddbOd]

This question gets asked at least every 6 months and the answer is essentially always the same...

Originally Posted by Toni Wilen

It will happen someday but it has really low priority..

[Toni Wilen]

Exactly. And I want answers, not questions..

Answering questions like "Why?" or "MMU would be useful for <put something here>" may make it happen faster.

[BlueAchenar]

I prefer dreaming of a multi 68020+ CPU Amiga At least we could use one Intel core per emulated Motorola. I just think the Amiga's task scheduler would need to get tuned...

[laser]

for ex MMU will be useful for Fusion and Shape shifter emulators....they can use MMU refreshed gfx drivers

anyways that emulators are fasters without MMU drivers and
I prefer that Toni add Overlay support to winuae instead MMU...it will be more useful

[Toni Wilen]

Originally Posted by laser

for ex MMU will be useful for Fusion and Shape shifter emulators....they can use MMU refreshed gfx drivers

I think using host native emulators is more useful..

I prefer that Toni add Overlay support to winuae instead MMU...it will be more useful

You mean Picasso96 overlay? No documentation, nothing at all.

[laser]

Originally Posted by Toni Wilen

You mean Picasso96 overlay? No documentation, nothing at all.

yes..I'm talking about the PIP or overlay feature of the Picasso IV

so...I have a question...sorry
who designed the P96 drivers for the picasso 4 ?
Village Tronic or the P96 team ?

[gilgamesh]

With a MMU we could run Amix or NetBSD or something. It is not necessary for playing games, but an exact emulation would make WinUAE interesting for teaching system programming and operating systems, etc. etc.

Also, it is a question of elegance to me. When emulating an 68040 there is always an important feature that is left out in the moment.

The repeated questions clearly show that many people are interested in a MMU for some reason or another.

[OddbOd]

Surely you already know what the answer's going to be?

Originally Posted by gilgamesh

With a MMU we could run Amix or NetBSD or something.

To parapharse from the reply above:- I think using host native Operating Systems is more useful.

Originally Posted by gilgamesh

It is not necessary for playing games, but an exact emulation would make WinUAE interesting for teaching system programming and operating systems, etc. etc.

Almost no one was interested in AMiX - which after all is just another UNIX as is NetBSD - when it was released, what has changed since then?

Originally Posted by gilgamesh

Also, it is a question of elegance to me. When emulating an 68040 there is always an important feature that is left out in the moment.

To quote Bernd Schmidt, "I was originally, and I still am really only interested in Amiga 500 emulation because that's what I had, I never really had any of the newer Amigas."

Out of the 50 or so very smart people that have contributed to UAE over the years none of them have shown enough interest in MMU emulation to bother implementing it, the two logical conclusions to be drawn from this lack of interest are that it's not a trivial task and that it's not considered essential by those that know the Amiga intimately.

[gilgamesh]

Alright then, most UAE developers obviously are not interested in MMU support. Some users obviously are.

Here is my last argument:
There is an emulator with MMU support for Atari, but none for Amiga.



(Btw. How does ARAnyM perform in comparison to UAE? Did anybody around here care to check that?)

[Toni Wilen]

Amix is not good enough reason because it needs 68030 MMU. (extremely complex MMU)

Originally Posted by gilgamesh

There is an emulator with MMU support for Atari, but none for Amiga.

There are more unique programs that require MMU for Atari than Amiga?

Amiga has none (I mean Amiga unique programs, not some Unix ports..)

[gilgamesh]

Was this a rhetorical question? If not:
I have no idea. I found no relevant info on the net besides the fact(?) that all STs had a MMU. That design seems to be more common in Atari environments.


Maybe they just wanted a testbed for Linux m68k etc., or simply for the sake of completeness? Or maybe they just wanted to have one first.

[alexh]

ST's do not have MMU's.

They had a custom chip that was nicknamed the MMU but it is not a real MMU it is akin to the Gary/Gayle chip present in every Amiga which is the interface between the CPU and DRAM.

A vanilla ST can no more run linux than a vanilla A500 can (at least not the kernels with memory protection)

[OddbOd]

ARAnyM doesn't just target the ST it's goals include running TT and Falcon software as well. Modern operating systems for those machines, primarily MiNT and Linux, are supported but they require an 030 or better as they use memory protection and thus need an MMU.

Linux running on a stock ST/A500 is about as practical as a chocolate teacup.

Originally Posted by gilgamesh

There is an emulator with MMU support for Atari, but none for Amiga.

If that was a shock see how this grabs you: ARAnyM's 68k emulation/JIT compiler is a fork of the UAE core, the MMU emulation is a continuation of Wez Furlong's patches to get 68k Linux running under UAE, so you see attempts have been made.

[gilgamesh]

Originally Posted by OddbOd

If that was a shock see how this grabs you: ARAnyM's 68k emulation/JIT compiler is a fork of the UAE core, the MMU emulation is a continuation of Wez Furlong's patches to get 68k Linux running under UAE, so you see attempts have been made.

Aaaaargh.... Hey wait, I knew that.

Anyway, I hear those voices telling me: Go and install Linux or BSD under UAE and then you buy that beatiful chocolate teacup...

Now I'll stop thinking about MMU support before the idea gets obsessive.

EDIT: Forgot one thing: Wouldn't the Aros people love MMU support?

[Interceptor]

Originally Posted by alexh

ST's do not have MMU's.

They had a custom chip that was nicknamed the MMU but it is not a real MMU it is akin to the Gary/Gayle chip present in every Amiga which is the interface between the CPU and DRAM.

do you have or can you point me to any docs on this ST "MMU" chip?

[alexh]

Your best port of call is ijor aka Jorge Cwik

There is a bit about it in one of his docs here:

http://pasti.fxatari.com/68kdocs/Ata...eCounting.html

Other sources:

The MMU's primary job is to interface the processor with the system's RAM (memory). It also works with the system's video chip to produce the video signal for your monitor—giving it access to the RAM which contains the data for the screen. Further, the MMU works in conjunction with the system's DMA chip, for passing data between RAM and the DMA/hard disk and floppy disk ports.

[vandam]

Originally Posted by Toni Wilen

Exactly. And I want answers, not questions..

Answering questions like "Why?" or "MMU would be useful for <put something here>" may make it happen faster.

Some time ago I voted for MMU (see http://eab.abime.net/showthread.php?t=24292 ), and there was not much approbation for it.
I also suggested to implement PPC in order to play some fantastic games and run stunning demos.

I'am stiil for implementing both features mentioned above. Anyone will support my suggestions (MMU & PPC)?

Regards.

[Toni Wilen]

Better edit above post (remove off-topic part) or this will be locked later today.

This thread is only about MMU.

[alexh]

Originally Posted by vandam

implement PPC in order to play some fantastic games

Name one?

Originally Posted by vandam

Anyone will support my suggestions (MMU & PPC)?

Only if you volunteer to implement them. WinUAE is open source, get coding.