M68K for DC

Greetings !

A new project is being created in order to bring M68K emulation to the DC.
In this case our bet, is to create an emu for the Dreamcast which will bring to our consoles the next systems:

Commodore Amiga 500
Atari ST
Apple Macintosh Plus.

The three computers uses the Motorola 68000 Cpu, and we're compiling info about the emus that already exists in order to port or redesign the cores and the related info.

A good name for this project could be the DC Triple A.
All knowlegde and efforts to convert this idea in a real project will be welcome and appreciated.

Anyway the main team is formed by: Ron, Pablo, Propeller and Mekanaizer. (JMD joins us ;-) )

Ideas and suggestions please, this will be great for all M68K lovers.

Thk Wraggster for all your support to the Spanish DC Scene

You can add the X68000 japaneese computer in your M68k computer list.
But the Triple A name not match anymore ;)

That's a great news because the 68k core is used in so many console/arcade/computer plateform.

What's kind of help do you need ?

Yes, thats a circumstance that we have already taken. The X68000 is a great computer and an oppoprtunity for all of us. The name is just a suggestion, so, if You are able to colaborate ;D Welcome aboard. Thx for your post , hope to see you soon.

Mac, amiga , You do know m68k is also neogeo. And genesis what are you going to do? these cores are Around now C cores that work on dc. Are you going to rewrite the m68k in sh4 asm. If not what is the point Stef D is rewriting from scratch his m68k core for dc.

Or is this to port this emulators.. because the m68k is fully emulated on the dreamcast right now. You will not need to redo them the mame core works fine check the makefile and or source of the neogeo emu.

Amiga500 is very hard project of course any thing i can do to bring the worlds best 16 bit computer to dc i would try but i dont hold much hope of it.

I'll collaborate too, Ian... Thanks for your work, you are a great comrade!

Propeller

[quote author=Ian_micheal link=board=dcemu;num=1083323639;start=0#3 date=04/30/04 at 15:03:12]
And genesis what are you going to do? these cores are Around now C cores that work on dc. Are you going to rewrite the m68k in sh4 asm. If not what is the point Â*Stef D is rewriting from scratch his m68k core for dc[/quote]

Is he? :-X

...


:o

sounds like a great new project, i wish you well.

Amiga emulation on the Dreamcast would be quite a feat.

Is this going to be a modular m68k core? because as ian mentioned the m68k was also used in the Neo Geo systems, in the Sega Genesis (megadrive) and in many arcade machines.

Also, will this be from scratch, or a modification of an older core? Currently the Musashi v3.3 m68k core from MAME works fine on the dreamcast, and offers some emulation of m68k variant chips. if not, i assume there is no way you would make it API compliant eh? (hehe)

If you were planning on starting from an all C core and rewritting in in ASM then Musashi is probably the best place to start.

Good NIght from MadriDC.
We're going to meet tomorrow to discuss about how to organize the development of the EMU, and what elements are going to be used, about the cores, and to trace a plan to sort our purposes. You will be prefectly informed. Thx to all who are supporting this beauty project.

Good luck to you guys ;)

That's great, dudes... I hope you'll succeed, and I can help by putting on some links for roms(amiga). I have on my girlfriend's PC winuae emulator that I use to play some of my favorite games from my younger days... But on the dreamcast... What can I say, I've been waiting for this day!!!
8)

only freely available roms/disk images, no illegal stuff please :P

Yes please. We don't support Ilegal. warez or in any case copyrighted material. Just a couple of comments. Do not post links to ROMS or manufacturer contents, plz, follow the rules. We are sure that everybody knows prefectly how to get that kind of tools. If you don't own the original machine to be emulated, do NOT ask US where to get it. Try in a internet searcher. That's all folks, old friends.

As Ian said, i'm currently writting a new M68K core in C.
It nearly completed, it can already play some genesis games :) (some opcodes are still missing and some bugs need to be fixed though).

The good point : it's faster than current fastest C core (aka Musashi).
The bad point : it take a long time and memory to compile (600 MB and about 5 minutes with optimisations set to O1)... this is because GCC doesn't like to have so many switch case in a single function (unfortunatly i don't have choice ...). So we have to avoid useless recompilation of the core ;)

I don't know if this can be of some help for your project, maybe you're directly writting an ASM core which is even better for the DC :)

Well, thanks a lot for your info... I knew nothing about it! Of course, it will be a source of inspiration for us, there's a lot of research work that doesn't need to be performed if you already have done it. We're thinking of our core as an ASM one, because that's the point next to yours on the roadmap.

C core -> optimized C core -> asm core :)

Of course, this means lots of work and we'll not face it till the MadriDC eve is done, but we wait for further news on your core with a *big* hunger.

Propeller

Six hundered megabytes!

Wow... That's a lot. I guess that's because of the size of the data structures you'd need if you had one function with switch statements for the entire set of M68k opcodes. Still, sounds like there might be some issues with the compiler if it's that big.

Here's the big question - does it work on the Dreamcast yet?

To the team for the new project, what is this new thing gonna be? are you making a new core, or rewriting an old one? if you are rewriting an old one, which?

also, stef, is your new core gonna be at all API compliant with musashi? (crosses fingers) that would be nice... [ /is happy because has 1.25gb of ram ;D ]

I would like to name Mekanaizer because he has lots of good and brilliant ideas. As We said days ago the project wouldn't begin until the party MadriDC is over, but all the views are oriented in the direction of the ASM core, to improve the highest performance and quality when emulating.
Keep it up this project, it's calling attetion for many many coders ,so if we can count with Ian Michael's knowlegde should be an extraordinary new for all DC coders community. THX !!!

Not to be negitive but I dont see this going anywhere because hardly any coders actually know Sh4 ASM. Now even if you use the S4h book and look up string by string conversions you SH4 may be less optimized than the C core because it will most likly be sloppy if you're not use the the language.

Also even once you have this core in asm we all know this isnt the end all solve all problem for coding. DreamSnes is the best example of this. Writing the core in ASM gave extremly lack luster speed ups compared to what they thought it would. Most of the processing power is killed in sound and video. This is a huge problem because you cant use the same video code for every emu without having to change some of the code correct? And if you have to change SH4 code wouldnt that make it so only about 3 of you would be able to use these cores as only 3 of you know a hand full od Sh4....


BTW 600MB sound's exstordanily big for a simple core.....

Quote:

---

Six hundered megabytes!

Wow... That's a lot. I guess that's because of the size of the data structures you'd need if you had one function with switch statements for the entire set of M68k opcodes. Still, sounds like there might be some issues with the compiler if it's that big.

---

Well, all opcodes are implemented in *one* function ... and each opcode is defined with its own scope, GCC doesn't like that much ... actually the main source file is "only" about (edit) 780 KB, but all that scopes make GCC to eat many memories !

Quote:

---

Here's the big question - does it work on the Dreamcast yet?

---

Hehe ;)
I didn't tried since a long time on DC, but it worked ... with optimisation level set to 1, anyway it was already really fast with that level of optimisation :)

Quote:

---

also, stef, is your new core gonna be at all API compliant with musashi? (crosses fingers) that would be nice...

---

For the moment not really :-/
Musashi does use "byte swapping" stuff where C68K (name of my new core :p) doesn't use it, but i'm thinking about adding "byte swap" optimisation as a switch in definition (shouldn't be too many work actually).
I'll also try to make others functions more musashi "friendly" but they will never be 100% compatible since i don't like how some stuff are done in musashi (IRQ and 'Exec' function).

I made an interface in the PC version of Genesis plus which allow swapping between Musashi and C68K "on the fly", sources will help to make change switch easier :)

[quote author=Clessy link=board=dcemu;num=1083323639;start=15#18 date=05/03/04 at 14:42:10]Not to be negitive but I dont see this going anywhere because hardly any coders actually know Sh4 ASM. Now even if you use the S4h book and look up string by string conversions you SH4 may be less optimized than the C core because it will most likly be sloppy if you're not use the the language.
[/quote]

I'm not a master of SH-4 assembly but i believe that it is quite simple to do a faster M68K core in SH-4 ASM than in C.
- First because a CPU emulator is really something where ASM will always keep a big advantage compared to C. For instance, emulating a ROR instruction with the correct flags need many C instructions where a few of ASM ones does the job...
Generally, just because of flags calculation stuff, ASM performs a lot better than C in CPU emulation.
- Second : the only SH-X C compiler we can use here is GCC, and unfortunatly it isn't the best C compiler for this CPU :-/ Generated code is somewhat a mess ... some values written in registers are never used later ...

IMO, a good knowledge of fast CPU emulation methods is more important than a good knowledge of SH-4 assembly :)

Quote:

---

Also even once you have this core in asm we all know this isnt the end all solve all problem for coding. DreamSnes is the best example of this. Writing the core in ASM gave extremly lack luster speed ups compared to what they thought it would. Most of the processing power is killed in sound and video. This is a huge problem because you cant use the same video code for every emu without having to change some of the code correct? And if you have to change SH4 code wouldnt that make it so only about 3 of you would be able to use these cores as only 3 of you know a hand full od Sh4....

---

That's true, almost time video code is the bottle-neck.
But i don't think ASM can bring a big speed boost here compared to CPU emulation. Just have to optimise code and maybe use hardware acceleration where it's possible :)

Quote:

---

BTW 600MB sound's exstordanily big for a simple core.....

---

I agree ;)
I upgraded memory on my laptop just for that Â*:P

I totally agree with Stef.

One of the "outputs" of this project is going to be a quick manual to SH4 newbies, in an effort to provide the scene with more people familiar to SH4 asm. It's a necessary condition that would eventually guarantee the quality of the results of the Dreamcast scene in the next couple of years.

Propeller

I just want to comment on a couple things, I am all for this project, but I don't think
amiga 500 would work on DC, I mean with full speed and sound because the amiga (this and
commodore 64 are best of the 80's cpus IMO} is too complex, but I can see atari ST and maybe
MAYBE the Apple but I don't see that either, not to be negative but I for one would be up on
amiga like a woman *whistles* but I just don't think the DC can handle a perfect amiga emu
if so I will so be shocked :}

Let's be serious here son the DC and play PSX games with super Ehanced graphics and you dont think it can handle a 80's pc....? I Sadly think your mistakin. Once everyone knows Sh4 your gonna see alot of kick ass emu support for DC game almost like a rebirth.

Its only a matter of time until we many coders who know sh4asm like the back of their hand.

wouldnt it be fitting for the homebrew scene to release something thaat stuns the software world.

Just remember what the donkey kong country games did for the snes.

Its like having a car and tweaking it everywhere to squeeze the perfomance out of it.

One day we will see smoe amzing releases, the neogeo cd emu is one such release.

ok, if fullspeed and sound amiga emulation happens of the DC, I will probably have a heart
attack, cuz what I wouldn't do to play risky woods on the DC, Ian micheal knows how much I
love the amiga, heh. I tried using the amiga emu called "winUAE" (sorry for being offtopic}
and I cannot get the fudging thing to work right, it sux. I hope the "rebirth" if it is a reality
happnens, to play "never thought possible" on dc, that would be definately a dream on DREAMcast
:}.

Hmm i think your forgeting how complex the amiga is here. Your have to have cycle perfect emulation it's more complex then a snes in some ways more then a psx. Im sorry to say i dont beleive it could be done at a playable speed. Just because it's a 80's pc means nothing.. SH4 asm is not going to totaly fix or help you port a very complex emu that uses lots of c++ kos does not support.

I can go throu in detail if you dont beleive me but amiga cant be underclocked or messed around with has to be perfect emulation. Â*I dont think you guys know how complex an amiga is compaired with an atari st. It has masses of custom hardware the amiga for video and sound and many cpu's much like the saturn.

[quote author=Ian_micheal link=board=dcemu;num=1083323639;start=15#26 date=05/05/04 at 06:05:09]Hmm i think your forgeting how complex the amiga is here. Your have to have cycle perfect emulation it's more complex then a snes in some ways more then a psx. Im sorry to say i dont beleive it could be done at a playable speed. Just because it's a 80's pc means nothing.. SH4 asm is not going to totaly fix or help you port a very complex emu that uses lots of c++ kos does not support.

I can go throu in detail if you dont beleive me but amiga cant be underclocked or messed around with has to be perfect emulation. Â*I dont think you guys know how complex an amiga is compaired with an atari st. It has masses of custom hardware the amiga for video and sound and many cpu's much like the saturn.[/quote]

Having CPU cycle emulation will improve a lot compatibility, but it's always possible to do a scanline based amiga emulator.
I think it's possible to have a full speed amiga emulator (without extras chips) with 80% software compatibility on Dreamcast... but is it really interesting to have a standalone amiga 500/600 emulator with only 80% compatibility rate ?
Remember Genecyst (a genesis emulator), Sardu made some choices, he volontary faked severals hardware features but then, he got about 85% of games playables at full speed with sound on a simple Pentium 100.
It was at this period the best choice ;)

Beleive it when i see it Stef. But ive run a lot of tests doing that breaks almost 80% of games not the other way around still was not fullspeed or even close to it.


Much easyer to do a gba emu then this. Amiga you need cycle perfect emulation or all games break not just a few like the genesis.

Well i though that WinUAE used a dynarec for the M68K CPU, how it can do perfect cycle emulation with a dynarec ? and WinUAE does work at fullspeed on old machine (i speak about amiga 500 or 600)...

Anyway i don't know the amiga hardware much... so you're probably true.

[quote author=Ian_micheal link=board=dcemu;num=1083323639;start=30#30 date=05/05/04 at 15:25:43]
specs for the old machine it works on you have tryed are. Ive tryed it on a 200mhz p1 Â*about 30% speed with sound on. I can take a video of it to prove it.

[/quote]

http://eab.abime.net/showthread.php?t=13374

Olders version of WinUAE were faster... and from another guy, Fellow was even faster.
but i guess they were a bit optimist ;)

Check black aura's posts. At dcemu I post them. Most of these people saying fullspeed have never used a real amiga neogeo cd sdl dc some people say fullspeed it's hardly even close to it in real world.

Any way check black aura's post on it. Im an amiga fan i like it the most just not going to happen. Fellow is x86 asm not portable


Yeah lot of people on forums like to lie or confuse speed with whats real. Amiga in real life runs a lot better then UAE and FELLOW ever Â*does even on mu 850mhz AMD it's still Not perfect emulation or very speedy to me.

This week end im having an amiga week end ive got 500+ real games in box's to revist and my amiga 600/40 is going to get a dusting off. I love a dc one Stef really but i cant tell people. Fairy tales. We dont have fullspeed snes emulation, An amiga is up to 3 times more complex. Thats just the facts from a programing standpoint. No amount of SH4 is going to completely save you when the system is this complex.


|Now ive looked all over dcemulation for you anthor post about amiga emulation on Â*DC


BlackAura
DC Devver



Joined: 30 Dec 2001
Location: Nowhere
Posted: Mon Dec 16, 2002 6:25 am Â* Â*Post subject: Â* Â*

--------------------------------------------------------------------------------

karsten wrote:
Well now i'll ask a noob question: (don't flame please!)

why nobody tried the amiga emulation? Amiga had greats games, and the machine wasn't really powerful (a 133mhz pc emulates it well). Is it about the amiga OS or porting difficulties?


You've seen an emulator that runs well on a 133MHz PC? Where? Last I checked, they needed a 400MHz CPU to run well. The fastest I've seen was Fellow, which ran well on a 300MHz machine, but they need at least a 500MHz machine to run most games at full speed.

The problem is that the Amiga is a stupidly complex machine, and it's also pretty powerful. Complex machines are very slow to emulate, as are powerful ones. And they're also really hard to write emulators for. That means that you might see a port of UAE to the Dreamcast, but it'd be unusably slow, and it's not likely that anyone will write one from scratch because it'd take years to get it working well.


Case you missed the links i posted on the subject

http://www.dcemulation.com/phpBB/vie...;highlight=uae whole topic.

http://www.dcemulation.com/phpBB/vie...;highlight=uae

http://www.dcemulation.com/phpBB/vie...;highlight=uae

many more at dcemu.. Black aura Knows what he is talking about one of the best programers i know dc or pc.

Im sorry i belevie him over some unknown people on emulation forums. Really is not that doable at all i dont see it being a chance at all.

But let all this info server some one to prove us wrong. No way i could do it even with a big team.

Can i ask if older versions of emulators that worked on pentium 100s etc, would be far easier to port to the dreamcast than recently released sources?

for example snes/genesis emus than ran well on a pentium

I dont know why people are so damn worried about amiga yet. One no ones even started on this Sh4 core and secondly we have tons of other emus much easier to make they arent anywhere near close to fullspeed.

Genesis should oe been done by now and I dont understand why some coders cant get together and finsh it up. Dont even say its to complexed to finsh it up when Ian's version with sound ran pretty decent and was just missing tons of features. Add in the frame skip by quazr and this new Optimized M86 C+ core then you'd have full speed.

@Stef D
I'd like to welcome you to the DC scene and I love to see you working on a Genesis/M68k emulator for DC! BlackAura is a nice guy and I am pretty sure that with IMRtechs help and the ppl working on the DC Triple A project this whole thing definitly will have a bright future...

For me u truly are a hero since I never had as much fun playing my Genesis games as with wGens! I wanna thank you for a long long very dark year that u brought some light into...


@Ian Micheal
I think you might be wrong because there definitly IS a way of emulating the AMIGA500 but I don't think that anyone has enough breath to do this til it's finished and playable with sound but even this could be proven as wrong...

Bleemcast, Genecyst etc are very good examples for fast and good programming!

...might be as hard as doing an N64 emulator 4 DC from scratch ;D but it could be done!

No one believed to ever see a good working NeoGeo(CD) emulator for DC too - but u and all the others working with you made it reality! Not to mention that it might be perfect within the next months :o
Everyone simply would have laughed at u if you'd announced that a year ago ;)

Damn I love NeoCD :)

So plz stop flaming :P and give them some helping hand ;)

No wonder I can't run risky woods off winUAE I have a 500 mhz and it run but the sound goes
too fast and the game is slow. I need to track me down a real amiga and a copy of risky woods
the music in that game rocks and winuae and Fellow KILL IT. amiga without music is like
cake without frosting, AIN"T GOOD ENOUGH. now the atari st emu I am all for because I like
the ST despite its extremely weak sound chip, can't produce quality tunes.

Not to be a downer but Im not wrong and ether is Black aura on this subject

http://www.dcemulation.com/phpBB/vie...;highlight=uae Â*whole topic.

http://www.dcemulation.com/phpBB/vie...;highlight=uae

http://www.dcemulation.com/phpBB/vie...;highlight=uae

http://www.dcemulation.com/phpBB/vie...;highlight=uae


Christuserloeser Â*im not flaming but giving the facts to save people wasted time. Im a big commodore fan amiga port was my first project. I know it cant be done. ive tryed

Why dont we work on nogeo cd it's near perfect and only needs a little push from other people i cant seem to fix cd audio on all games or get sfx to work right. It's open source. If were working for the greater good then it's a good project. Many others that need finshing like wonderswan all of use working on it would be finshed.

Just a thought should we not finshes things that are unfinshed im only a porter and c code haker.

an, you know your amiga, I also know that the Dc cannot handle the great power of the amiga
amiga in their games and apps, utilizes the different processors that the amiga has, the DC
just cannot do it, I wish people would realize it, Ian you explained it PERFECTLY. IF it happend
then I can call myself a liar, but until it does I still think the programmers that think
they can pull amiga off are living too damn much in the dream world.

Anyway guys, emulating the Amiga 500 is not the only point on this idea. An asm done 68k core for the sh4 would undoubtely improve things. If it's possible to emulate Amiga, we'll do it, but it's not the only point I see on this proposal. There's a lot of fun hidden in here, and everyone is called to collaborate. And don't set the Amiga emulation as the only goal, because I think that the next step in dcemulation will be doing fast mean and sharp asm cores, starting from the most commonly used ones, and this means m68K.

I also appreciate Ian's interest on this subject: Undoubtely, there's not an *easy* or *fast* way to emulate Amiga, but we may keep searching for a way to achieve a good compatibility combined with fast (but not complete) hardware emulation.

Thanks for all of your replies, I'm so happy that this topic suggested a hot, interesting discussion.

Propeller

[quote author=Christuserloeser link=board=dcemu;num=1083323639;start=30#34 date=05/05/04 at 22:08:36]@Stef D
I'd like to welcome you to the DC scene and I love to see you working on a Genesis/M68k emulator for DC! BlackAura is a nice guy and I am pretty sure that with IMRtechs help and the ppl working on the DC Triple A project this whole thing definitly will have a bright future...

For me u truly are a hero since I never had as much fun playing my Genesis games as with wGens! I wanna thank you for a long long very dark year that u brought some light into...
[/quote]

Thanks for your cordial accueil :) I'm happy to see you had fun using Gens, this is our reward Â*;)
I always followed the DC emulation scene but i never really had the time to involve myself inside ... until recently.

I know Ian and BlackAura, they are both great and talentued dever guys, I'm sure we will do nice stuff together ;) I don't know much "DC Triple A" team, but they seem to be really motived, it would be nice to join our effort on commons projects (who said M68K ? Â*;D )

Hopefully, i'll be able to complete something i started (speaking of the 68K core in C)... didn't happened from a long time !

About Amiga emulation on DC, well, i can't really estimate what the DC is able to since i never coded in pur SH-4 assembly using internal cache stuff ... nor i can't estimate how many CPU power requires amiga emulation since i don't know it's hardware much ...
But is it really important ? i don't think this debate will bring us somewhere... let's go coding instead Â*:D

I just realized i got the "DC coder" status Â*:-*