Next game to port?

[roondar]

Originally Posted by Havie

If I had my own personal choice then I'd go for Salamander - love this game and the C64 had a decent version so how amazing would this be on the Amiga???

On second thoughts... Cancel my 'vote' for Gauntlet

This would be awesome. I absolutely loved the C64 version back in the day and it's good fun on the PC Engine as well.

[malko]

Originally Posted by roondar

This would be awesome. I absolutely loved the C64 version back in the day and it's good fun on the PC Engine as well.

You should give a go to the X68000 Gradius/Nemesis version
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Not played yet Salamander on the X68000
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[Anubis]

Original Arcade WonderBoy will be great to have on an Amiga.

[malko]

It's not on the list and I know it would require an amazing workload (disassemble DOS code first?). Anyway think the A1200 could maybe support a good conversion : Ultima Underworld.
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After all, A500 got Wing Commander
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, so why not an Ultima Underworld on A1200 ?

[malko]

Originally Posted by Anubis

Original Arcade WonderBoy will be great to have on an Amiga.

Actually, it a nice surprise to see that it's the game having the more vote for a conversion (14) .

[drHirudo]

I voted for the WonderBoy, because it is a perfect game to utilise the Amiga chipset capabilities and it is a shame that such good game has C64 port, but not an Amiga one.

Regarding the older arcade ports like PacMan and Space Invaders - there are already hundreds of remakes on the Amiga of these games done in AMOS, Blitz BASIC, C, Assembler etc... For pixel perfect conversions, an emulator will do the job just fine. The 68000 speed of Amiga 500/1000/2000 can emulate Z80 pretty fast. When I used Amiga 500 as main computer, I remember emulating Sinclair ZX spectrum (more complex machine) on it at acceptable (33%) speed, thanks to the emulator Speccylator, which is now open sourced - http://aminet.net/package/misc/emu/Speccylator-src
An Amiga 1200 with fast RAM can emulate Z80 based machines pretty well - for references just check AmiMSX, AmigaMasterGear, AmiGameBoy.

[jarre]

for me absolute: Raiden & Raiden II

[malko]

Originally Posted by mcgeezer

Wow... I followed that link and the cost of Gauntlet was £25 in 1990!
That in todays money is over £50...
[...]

Between two bug searches/hunts/fixes on Rygar, you can read this Graeme .

[jotd]

The 68000 speed of Amiga 500/1000/2000 can emulate Z80 pretty fast

1) not true. A 68030 can emulate a Z80 properly. A 68000 is too slow.

2) but even with a fast cpu, the video display remains the biggest issue (and also the audio). The emulator would have to be tuned to display the objects, not just draw the entire screen pixel by pixel (chunky!), since the amiga cannot do 50 fps with a full CPU-driven screen refresh, specially with C2P.

That's why MAME doesn't work that well, even on 68060 CPUs. To do that we would have to emulate the Z80 "functional" code, but handle graphics & sound natively. In that case, better re-code the algorithm in 68000 directly.

[Estrayk]

Originally Posted by jotd

1) not true. A 68030 can emulate a Z80 properly. A 68000 is too slow.

I'm totally sure that you have plenty of knowledge to affirm that, in fact I also thought so, but the other day, I tried a spectrum emulator in my old Atari and to be honest, I was surprised how well it runs with a 68000 at 16mhz.

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[saimon69]

I remember using the emulator in my a500 and had to use frameskip=3 to have it kinda playable, around same speed than that

[nobody]

The fastest Spectrum emulator I tried on A500 was running about 50% of real speed with ACA500+ 68000 @21 mhz. As per my calculations you would need a 68020@28 mhz for 100% speed. Talking about 48k only emulation.

[drHirudo]

Originally Posted by jotd

1) not true. A 68030 can emulate a Z80 properly. A 68000 is too slow.

Eh, people already gave examples of Z80 full computer emulations running at acceptable speed on 68000. Additionally, Sinclair ZX Spectrum CPU is clocked at 3.5 MHz, while the Pac-Man uses Main CPU: Zilog Z80 @ 3.072 MHz - https://en.wikipedia.org/wiki/Namco_Pac-Man

Space Invaders uses even slower CPU - 8080 @ 2 MHz. Similar to Z80, but even simpler/easier to emulate.

2) but even with a fast cpu, the video display remains the biggest issue (and also the audio). The emulator would have to be tuned to display the objects, not just draw the entire screen pixel by pixel (chunky!), since the amiga cannot do 50 fps with a full CPU-driven screen refresh, specially with C2P.

Why refresh the whole screen when for example with Pac-Man you have only 4-moving ghosts and the Pac-Man and on Amiga you have at least 8 hardware sprites, that can moving freely around the screen without much CPU overhead? For the audio, several KBs of sampled sounds will happily stay in Amiga' memory, since the game logic and graphics (in the cases of Pac-Man and Space Invaders) are pretty small.

That's why MAME doesn't work that well, even on 68060 CPUs. To do that we would have to emulate the Z80 "functional" code, but handle graphics & sound natively. In that case, better re-code the algorithm in 68000 directly.

MAME is written in C/C++ for high-end CPU. And in fact it main purpose is not emulating, but documenting the old hardware -https://docs.mamedev.org/initialsetup/mameintro.html

being able to play games on in on modern hardware is a nice side effect.

68000 assembler with some custom code for the graphics will recreate the original Space Invaders and Pac-Man on Amiga pretty well, using the original game code, graphics and sounds.

[drHirudo]

Originally Posted by nobody

The fastest Spectrum emulator I tried on A500 was running about 50% of real speed with ACA500+ 68000 @21 mhz. As per my calculations you would need a 68020@28 mhz for 100% speed. Talking about 48k only emulation.

Don't forget this is interpretive emulation - i.e. the emulator doesn't know what instructions are coming next, so it waits and executes the instructions one by one. With the cases of Pac-Man and Space Invaders, you already have the whole game code loaded at startup, which allows for some speed-ups or even interpreting all the code in advance, which gives speed. There is such binary translator for Amiga for Atari 2600 - http://aminet.net/package/misc/emu/Electrostatic which shows very good speed for Atari 2600 emulation. Some years ago I translated many Atari 2600 cartridges

Skeleton - http://aminet.net/game/misc/Skeleton.lha
Vault Assault - http://aminet.net/game/misc/VaultAssault.lha
Warring Worms - http://aminet.net/game/misc/WarringWorms.lha
http://aminet.net/demo/euro/Atari2600Demos.lha

[nobody]

There was a uae4all version for arm that was running full speed at 300 mhz arm. It had 68k core written in arm asm. In fact I had that program in an old arm cellphone with 600 mhz and was running 25fps (sometimes 50) at all times with sound and everything. Now I wouldn't even try to start winuae on a 300 mhz pc.

[mcgeezer]

On the subject of emulating old z80/8086/6502 games such Pacman/Space Invaders/Galaxian I was always interested in writing a translator whereby you would load the rom code dumps and translate them to 68000 instructions.

The 68000 pretty much covers all of the registers and flags from these older processors.

You would also supply the mame driver for the rom which would read where the graphics data is and i/o ports... a watcher routine would be looking at the translated io ports and be behaving accordingly (moving gfx/sprites etc).

I think this would be do-able, but the beauty of it is you would have the translated source code to add additions etc. but the hard part is understanding the memory values/sizes.

Anyway... it was just a thought.

[Dunny]

Originally Posted by nobody

The fastest Spectrum emulator I tried on A500 was running about 50% of real speed with ACA500+ 68000 @21 mhz. As per my calculations you would need a 68020@28 mhz for 100% speed. Talking about 48k only emulation.

You'll need more than that if you want to do any kind of the mid-scanline colour changes that the Spectrum was capable of. A generally naive (and incompatible with quite a surprising amount of software) emulator would update the screen at the end of each frame, dumping screen memory to a surface. For this, an accelerated 68020 is fine.

But any graphical tricks requires quite a lot more CPU. Under windows, truly accurate emulation of the Spectrum requires at least 350Mhz, under DOS you can get it done at around 200MHz.

[jotd]

@drHirudo yes you're totally right. I already wrote some 6502 to C automatic translator. Z80 is of course doable to C or asm.

The advantage with asm to asm translation is that you can most of the time reuse flags like Z, N, V ... without testing them like you'd have to do in C (I coded Amoric, 1MHz 6502 oric emu on amiga with asm, overflow/negative/zero flags were the same, and when I wanted to do the same job in C, I had to copy some code to handle the flags, not so obvious).

When I said 68030 (25Mhz) I maybe was a bit presomptuous. At least I could reach 100% speed with that CPU. Maybe emulation code could have been sped up even more (but I already had help from someone to increase speed by 200%...). Also 6502 is maybe more powerful than Z80 (but slower freq).

The problem is that the machine has to take care of the CPU but also the video & sound (and other circuitry). So everyone is basically saying the same thing:

CPU is not an issue, but we'd have to extract the functional code and write specifics for Amiga.

If McGeezer can code drivers / adapt MAME for PacMan and other games specially for Amiga so it runs at 60Hz that would also rock
But MAME is really complex, specially newer versions. It would be easier to adapt a pre-2000 version/hack the already ported Amiga version.

[mcgeezer]

Originally Posted by jotd

If McGeezer can code drivers / adapt MAME for PacMan and other games specially for Amiga so it runs at 60Hz that would also rock
But MAME is really complex, specially newer versions. It would be easier to adapt a pre-2000 version/hack the already ported Amiga version.

I'm probably wrong but I can't see how doing it would be that difficult.

If you look at the pacman mame driver there's only's only a few memory mapped I/O ports...that would need to be intercepted.

memory mapped ports:
    read:
    5000      IN0
    5040      IN1
    see the input_ports definition below for details on the input bits
    write:
    4ff0-4fff 8 pairs of two bytes:
              the first byte contains the sprite image number (bits 2-7), Y flip (bit 0),
              X flip (bit 1); the second byte the color.  Note: Only Ponpoko has 8 sprites
              an original Midway Pacman board contains only the center 6 sprites.
   
    5060-506f Sprite coordinates, x/y pairs for 8 sprites

I'm not sure how it draws the tiles but I think that could be worked out I guess.

While I say it might be easy, it would also take a long time.

[DanScott]

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

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