Amiga emulators: is it worth it?

[amigaksi]

>by DiskDoctor on 2009/1/23 14:18:58


>@ shoggoth
>&@ amigaksi
...
>Old Amigas were excellences, though nothing divine. Sure it is theoretically possible to re-create this. But I do not think it is doable on the current PC stuff especially with all WinLinMac stars as middleware... Nowadays, like software (OS), like hardware.
...

I mostly agree but it's hard to assume it's "nothing divine" without some further evidence.

About using stand-alone boot-able Amiga that uses the hardware resources directly-- that would be a better approach.

[amigaksi]

>by Hammer on 2009/1/23 15:30:49

amigaksi wrote:
>>by DiskDoctor on 2009/1/18 9:57:56


>>Hello,

...
>>Also, some time ago I encountered some post on some other forum stating that "no one has ever managed to re-create the original chipset as a Virtual Machine because it was SO PERFECT it is hardly possible if ever."

>>>If you go by PC standard hardware, it is impossible to do the cycle-exact emulation of the Amiga. Now if you have some specialized PC hardware like a multi-channel audio card, sprite-based video card, digital joystick interface, PC w/HPET timers, etc. that are all superset of the hardware of your Amiga in every respect and have software that uses these directly (not through an API or buffered scheme), then it is possible.
(SNIP)

>To have design for Windows Vista logo on PCs, the PC must have HPET timers.

>Refer to http://msdn.microsoft.com/en-us/library/bb931844.aspx

Someone declaring a standard is different from being a standard (in reality).  I can declare the new timing standard for Amigas is 28.6363Mhz not 3.579545Mhz but that does not mean everyone has it.  By standard PC hardware, I mean you go to almost anyone's home and they have that hardware.  The 1.19Mhz timer is there in every PC.

I can offer some upgrade h/w that uses the 28.6363Mhz crystal on the Amiga MB and uses it to increment some register but it's specialized hardware.  Perhaps, I can get Microsoft to declare it an Amiga standard.

[amigaksi]

>by shoggoth on 2009/1/24 9:08:25

>>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.

Okay, so both words emulator and cycle-exact are different for both of us.  I am going by emulator defintion in dictionary and cycle accurate or cycle-exact to be 1/7.16Mhz for Amiga OCS.  

>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.
...
And the reason for that is deductive.  If you can't take some application on Amiga and make it on a PC as efficiently using it's native hardware, then it can't be done using an emulator regardless of how many millions of source code lines you show me.

[amigaksi]

>by Hammer on 2009/1/23 15:48:42

Quote:
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>bloodline wrote:
@amigaski

>Just for your info, the HPET is a 64bit, 10Mhz Timer...

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

>Does AROS use HPET?

10Mhz, that's all?  I thought the spec was for 14.318Mhz or higher.  10Mhz could be problematic as Amiga is using NTSC frequencies and not being evenly divisible by them would pose a problem in this case.

[amigaksi]

>>10Mhz, that's all? I thought the spec was for 14.318Mhz or higher. 10Mhz could be problematic as Amiga is using NTSC frequencies and not being evenly divisible by them would pose a problem in this case.

>Every PC has always had a 1.193182Mhz timer, this is 1 third the NTSC colourburst...

>But most Video cards have a VBL interrupt, and UAE allows you to sync the emulator to a real Video card VBL... I don't see how it could be any more perfect than that...

For frame rate, it may be good approximation, but there's other things going on in the system than video running at 60Hz.  And even the video is subject to latency and phase shifts.  Sure it could be better if every cycle was a real Amiga cycle in time.

[amigaksi]

>>by AmiKit on 2009/1/24 10:19:52

@amigaksi

>>I was pointing out that differences exist even in cases where YOU did not perceive them.

>And I accepted what you said if you did not notice. The point is somewhere else but I won't explain it to you ONCE AGAIN.

Okay.

>>Major differences also exist depending on target hardware used by emulator and it's spec.

>Sorry, but your knowledge about how emulation works was put in question here in this thread...

Definition was being debated.  I also put the shape of the earth into question earlier in this thread so what's the big deal if someone is questioning.  You and many others perceive the earth as flat but what's the reality?

>Seems you still don't get it.

I get it.  You see things as a whole not parts so when the video is out of phase or has latency with respect to audio, timers, etc. you will notice it.

>>Not "would be". It is already existing.

>Link please?

>>I can post source code or an ADF to a sample code I ...

>Yes, please. Or should I ask you for it for the fourth time?

I can't find where you asked 3 times.  I currently have it as a bin file that loads at absolute location $10000 so I need to convert it to ADF so it boots up.  It works consistently on OCS, ECS, and AGA.

>"...the operational principle of the brain is holistic, parallel, and analog, with self-organizing tendencies; or, that the whole is different from the sum of its parts. The Gestalt effect refers to the form-forming capability of our senses, particularly with respect to the visual recognition of figures and whole forms instead of just a collection of simple lines and curves."

>Sorry but in such a context the subtle differences between real and emulated game are simply irrelevant.

>>That's true but it actually supports me. Emulator is not an Amiga as a whole although some parts (like the static visual output) look the same.

>You did not understand it at all.

You apply the same principle to a flat earth.  I rather have a perfectly working "whole" with audio/video/timing all exact.

>[insults deleted]

[amigaksi]

>by -D- on 2009/1/27 17:19:59

>The emulator has to be synced to the display device for accurate scrolling, this means 50/100Hz for PAL software (unless you want to run PAL software at NTSC 60Hz for most LCDs, which screws some software). Running 50Hz settings (PAL/50 fps emulator setting) at 60Hz will visually mess the scrolling. This is admittedly more noticeable with certain games than others, also not all Amiga games featured perfect scrolling anyway. Fire up a pinball game though, or SOTB3 intro, and the difference (PAL settings at 60Hz) is plainly discernible.

>However - this is simply a matter of finding the right settings (and possibly an annoyance for LCD users who use UAE for gaming), not a dis on WinUAE which is obviously fantastic

I don't know if it's the right settings in some cases if the underlying hardware won't allow perfect synching at VBL.  And even then you have 119472 cycles in a normal field that are not cycle-exact.  That's 0.0008% cycle exactness even if you think the VBI cycle is exactly timed.