Amiga emulators: is it worth it?

[shoggoth]

amigaksi wrote:
If you go by PC standard hardware, it is impossible to do the cycle-exact emulation of the Amiga.

I'd like to see you explain that statement. Emulation granularity is *not* dictated by hardware capabilities such as timers, sprites, multi-channel audio chips. Generally that's not how you solve these things, at least not in any of the emulators I've worked on.

[shoggoth]

bloodline wrote:
Ignore amigaski, he is more ilinformed than a British General during the First World war...

Ah, ok that explains it. I'll try, but I might not be able to. My BS-o-meter just went off the scale.

[shoggoth]

amigaksi wrote:
It's good to have conversations and learn things but when you start insulting and poking fun at the other party, that "learning" experience goes away and it's more to do with biased emotional sentiments.

No, you're making false statements, and you don't appreciate when people correct them.

If I do have a bias, it favours amiga and other machines of that era. I appreciate the complexity and capabilities of these machines, but I don't let that blind me or prevent me from accepting technology today.

I claim that you have decided that these machines cannot be emulated accurately, based on wrongful assumptions about how emulators work internally. For that reason, I've explained how they work. If you don't want to accept that, you're simply rejecting reality in favour of your wrongful assumptions.

Accurate emulation depends on hardware capabilities.  I'll explain it further if I feel like it.

No, it does not. You need enough CPU power, that's it. You don't need high resolution timers or any of the other stuff you've stated.

Marat Fayzullin has written a simple yet very informative tutorial about writing computer emulators. You can find it here: http://fms.komkon.org/EMUL8/HOWTO.html

Marat is well known for his work. If you look at his source code, or the source code of 95% of the emulators on the net, you'll find that they do *not* rely on timers nor special hardware capabilities to ensure cycle accuracy. They do so by interleaving the code for each emulated subsystem. In the case timers are used, it's generally to throttle emulation so that it does not run too fast, or to skip frames to maintain speed.

[shoggoth]

by amigaksi on 2009/1/22 12:25:08
That's a false statement. Claiming that cycle-accurate should mean 1/7.16Mhz timing accuracy on OCS Amiga is false right?

No, cycle accuracy at 1/7.Mhz granularity is perfectly possible without using timers. Get those timers out of your head.

Based on facts about hardware of target platform and source platform (Amiga)

... based on facts about hardware - but not based on how emulators actually work. You've *assumed* that they work in a certain way using timers - which they generally don't (because it would be completely retarded to do it that way).

Regardless, of how fast your CPU is, it won't make your beep speaker (1-bit resolution) do 4-channel 16-bit 44Khz audio.

Now you're just being silly. Of course you need a soundcard to get proper sound. That wasn't the point - we were discussing emulation accuracy.

Regardless if your CPU is Pentium IV at 4Ghz, it won't improve your timers. And you can't time things equally or better with 1.19Mhz timer vs. a 3.57Mhz timer-- just seems to be violating some laws.

Drop timers. You don't use timers to achieve accurate emulation. That's *in* your *head*. You've chosen to compare this aspect of computers because it suits your ideas, obviously.

He is claiming any computer can be emulated because he defines "emulate" as an ATTEMPT to imitate the target machine. That means, you should also accept: Atari ST can emulate Amiga, Atari 800 can emulate Pentium IV dual core, Apple I can emulate the MAC II, etc.

LOL! So by this you claim that Marat Fayzullin has no idea what he's talking about? :-D Do you know who this guy is?

"... as an ATTEMPT to imitate" - well that's *exactly* what emulation is. And emulation accuracy is defined by compatibility and perceived user experience. Both which can be realized on any PC today. If you ignore the latter, even a ZX81 can accurately emulate a modern quad core x86 class machine, given enough time and memory.

I'll try to refrain from further comments now, since there is no point in discussing a topic such as this one with you. You're either incredibly ignorant or trolling, or both.

[shoggoth]

>... based on facts about hardware - but not based on how emulators actually work. You've *assumed* that they work in a certain way using timers - which they generally don't (because it would be completely retarded to do it that way).

Again that's your flawed idea.  You can make the emulators cycle-exact if you had an interrupt of 1/7.16Mhz accuracy and did everything cycle at a time instead of frame at a time which is only makes it "visually" appear the same except for the VBI not being in sync with WM_TIMER difference.

The term "cycle accurate" doesn't dictate the actual cycle duration. I've never claimed it did. What it means is that the state each subsystem is accurate on the cycle level - which have *nothing* to do with real time.

You're talking about timing. I'm talking about synchronization at the cycle level. That's not the same thing at all. You've got the definition for cycle accurate wrong, clearly.
 

>Drop timers. You don't use timers to achieve accurate emulation. That's *in* your *head*. You've chosen to compare this aspect of computers because it suits your ideas, obviously.

If your defintion of emulation means "an ATTEMPT" to mimic the target machine, yeah you can drop timers.  Otherwise, you should drop your ideas that you only need CPU speed to emulate any machine.

http://en.wikipedia.org/wiki/Emulator

Download the sources of some modern emulators and see how they work. They'll confirm my statements. Ah - oh now I remember - you didn't want to do that. You said you had nothing to gain by doing so. Right.

This is like discussing colour with a blind person. You don't know the fundamentals, yet you keep discussing them. You have your own definitions, and even though they differ greatly from that of the rest of the world you stick to them. You've seen a piece of the puzzle and somehow think that's enough to get the whole picture. I'll try to stop myself from answering any more of your posts, because you won't understand the message anyway. I think we've proved that several times now.

@bloodline
 - I get it now. Thanks.