Next game to port?

[mcgeezer]

Originally Posted by DanScott

They've already "emulated" the Pacman ROM on Spectrum...

[ Show youtube player ]

Nice!

Very do-able then I would say given my theory is probably right.

[jotd]

cool. But you don't want to compile MAME for amiga. You need to extract the useful parts. That is probably hell.

But if someone wants to do something like this (for several games using same hardware as Pacman) and you need some help in cross-compiling C/porting stuff, I'm in (maybe open another thread for this)

[kamelito]

https://simonowen.com/spectrum/pacemuzx/

[DanScott]

Originally Posted by jotd

cool. But you don't want to compile MAME for amiga. You need to extract the useful parts. That is probably hell.

But if someone wants to do something like this (for several games using same hardware as Pacman) and you need some help in cross-compiling C/porting stuff, I'm in (maybe open another thread for this)

No, you'd just interpret the native Z80 code on the Amiga... either realtime (slow) or by pre-processing it into equivalent 68000 instructions... (faster)

[jotd]

Dan, you'd just interpret the functional Z80 code on the amiga. There's a lot of non functional code to scrap. But the hardware isn't the amiga hardware. Takes some hard staring at the code (not to mention the special way the japanese coders have to do stuff that us europeans have a lot of trouble to understand)

The speccy version (damn impressive!) is probably much simpler to understand given the known & limited hardware of the ZXSpectrum. Someone already did the work and the source code is here: https://github.com/simonowen/pacemuz...r/pacemuzx.asm

The sound effects are really awesome too... That gives me some ideas. Would require transcribing Z80 code to C or asm (already did this with 6502 to C). The interesting part is that there is no "generic" stuff like in MAME, which makes things harder to understand. Excellent!

[mcgeezer]

Originally Posted by jotd

Dan, you'd just interpret the functional Z80 code on the amiga. There's a lot of non functional code to scrap. But the hardware isn't the amiga hardware. Takes some hard staring at the code (not to mention the special way the japanese coders have to do stuff that us europeans have a lot of trouble to understand)

The speccy version (damn impressive!) is probably much simpler to understand given the known & limited hardware of the ZXSpectrum. Someone already did the work.

I think in my simplistic world I would be writing a code pre-processor/translator in Python which takes a z80 code segment and spits out a 68000 code segment, at the end of the day the code is simply sending bytes to those IO ports so the Amiga then just has to watch what data is coming into those ports each frame and then drive the graphics updates as needed.

Obviously in the speccy version they didn't have to bother with the translation as it's rocking a z80 anyway.

I have to say I'm warming to this idea enough to give it a try.

[DanScott]

Without getting too technical... What mcgeezer says

[jotd]

the Amiga then just has to watch what data is coming into those ports each frame and then drive the graphics updates as needed.

basically what MAME does. But you have to be smarter to avoid redrawing all screen. That's where it will be smooth instead of choppy

I would be writing a code pre-processor/translator in Python which takes a z80 code segment and spits out a 68000 code segment,

exactly what I did for my 6502 conversions (except that it was 6502 opcode macros as C) and it works

I didn't test that but there's already a Z80 to 68000 converter here: https://www.lysator.liu.se/~celeborn...00/Z80CONV.ZIP with source. It's Atari basic, but not a problem to convert to python. I can give this a try. Looks professional

             CNVZ80 -  Z80 SOURCE TO MC68000 SOURCE UTILITY
 
                   (C) COPYRIGHT 1982 BY MOTOROLA INC.

[Dunny]

Originally Posted by jotd

basically what MAME does. But you have to be smarter to avoid redrawing all screen. That's where it will be smooth instead of choppy

Maintain an array of 296 booleans (or however high the screen is - the Spectrum is 352x296) and on each write to screen memory set a flag for that line. When the end of the frame comes and you update the screen image, just convert the lines that have been flagged.

I didn't test that but there's already a Z80 to 68000 converter here: https://www.lysator.liu.se/~celeborn...00/Z80CONV.ZIP with source. It's Atari basic, but not a problem to convert to python. I can give this a try. Looks professional

             CNVZ80 -  Z80 SOURCE TO MC68000 SOURCE UTILITY
 
                   (C) COPYRIGHT 1982 BY MOTOROLA INC.

Looks nice. It only converts sources, not binaries (which is not surprising!). However, here is Pacman's ROM as disassembled source:

http://cubeman.org/arcade-source/pacman.asm

Commented too, which is nice. Will need some massaging to get into a state where you can use it though.

[vulture]

@Dunny
isn't Speccy's resolution 256x192? Unless you mean something entirely different by 352x296

[Dunny]

Originally Posted by vulture

@Dunny
isn't Speccy's resolution 256x192? Unless you mean something entirely different by 352x296

The full border is 352x296. The actual size of the user-addressable display RAM is indeed 256x192. But with judicious use of OUT, you can draw in the border - hence why it takes a LOT more CPU to be able to emulate a Speccy accurately than most people would think.

[jotd]

Maintain an array of 296 booleans (or however high the screen is - the Spectrum is 352x296) and on each write to screen memory set a flag for that line.

That's what I did for the Oric emu on amiga and it was pretty efficient (there were very few scrolling games on the Oric )

MAME has/had a "draw only changes" option. But I suppose that it would be lost in the C2P final conversion anyway. C2P would have to use this line flag too (so finally adapting "draw only changes" to C2P routine in Amiga MAME could be pretty efficient too for non-scrolling games)

[vulture]

@Dunny

Ah ok, I thought you were talking about the usable resolution. I think Defenders of the Earth used the border for some effects.

[jotd]

Got MAME source for Amiga but the "main" source is missing for 0.35.12. Can't find it on mamedev.org. Too old. Someone, an idea?

[Retro-Nerd]

This one?


http://aminet.net/package/misc/emu/mamesrc

http://www.progettosnaps.net/MAME/src/m35b12su.zip

[ZEUSDAZ]

Don't care what anyone thinks of it but I wanna see Street Fighter 1 done properly on the Amiga, not expecting arcade perfectness but gotta be a whole lot better than what those morons at Tiertex / U.S. Gold ended up giving us,....followed by Rastan.

[jotd]

ok ZEUSDAZ if it weren't for Tiertex you'd be out of your job with your hilarious shit game time vids.

Retronerd: thanks! I'll check that. The c2p routine in Amiga MAME is in asm but processes the whole screen if I'm not mistaken. Time for a cross rebuild with gcc 6. If I can do that that will be a small miracle already.

Well sources are incomplete and nowhere to be found (ex: cpu/z80.c). Time to give it up... no big chance to succeed in doing something useful anyway...

[saimon69]

Originally Posted by ZEUSDAZ

Don't care what anyone thinks of it but I wanna see Street Fighter 1 done properly on the Amiga, not expecting arcade perfectness but gotta be a whole lot better than what those morons at Tiertex / U.S. Gold ended up giving us,....followed by Rastan.

Read somewhere about the April Fool 1989 by the italian edition of The Games Machine [Street Fighter US Edition] and you will find not to be alone: for YEARS people did write to the magazine asking when would finally be released...

[dlfrsilver]

Originally Posted by ZEUSDAZ

Don't care what anyone thinks of it but I wanna see Street Fighter 1 done properly on the Amiga, not expecting arcade perfectness but gotta be a whole lot better than what those morons at Tiertex / U.S. Gold ended up giving us,....followed by Rastan.

an experience could be done with this one.

Pick the arcade program, redirect the video ports and other regs, and adapt as much as possible the sprite tile builder engine.

but anyway, SF1 is a 128 colors game, if you don't want to denature it, a good A500 port would be a mess to do, more complicated than an A1200 port.

this game would take at least 2mb of ram, considering the sprites size.

I have quite a number of stages already ripped......

[ZEUSDAZ]

Originally Posted by jotd

ok ZEUSDAZ if it weren't for Tiertex you'd be out of your job with your hilarious shit game time vids.

LOL, yeah there is that I guess, good to know that series of mine seems enjoyable to others,....BUT I STILL WANNA SEE A BETTER CONVERSION ATEMPT AT SF1 THAN WHAT TIERTEX COUGHED UP!