FPGA for dummies

[Lord Aga]

No, I understand you perfectly.
But some may like FPGAs more than you and I. Or have their own definition of emulators.
Why carry on the discussions whether FPGAs are better than something or not, or are they emulation or not ? To some, if they are not ASICs then they are emulators. To others, if they can knock on it and they make a sound then they are "real" and not emulators. To some, they will be emulators no matter what, since they are not Moto's CPUs. So what ? Bring them on and let us see what they can do. Why argue semantics ?

[persia]

What I and others have disagreed with is the purity control folks who think that this is somehow more pure than UAE.  You may like the hardware emulation of FPGA more than the software emulation of UAE, but they are both valid ways to get a Classic Amiga like experience on modern equipment.  One's not superior to the other, they are just different approaches.  The last thing we need to to divide ourselves into more camps.

[kedawa]

Yes, the logic isn't the same. It is emulation.
 
Even though the FPGA's have extra functionality, they can still emulate the old functionality enough to run the old software.
 
Like it or not, it's emulation. Nothing about the word emulate implies using a computer. It means one thing trying to behave like another thing.

Oh I see.  So if you run an ECS game on an A1200, I guess that's emulation?

[alexh]

As many have said, it is not emulation. It is re-creation. Like all re-creations how accurate it is depends in the information you have on the original.

AGA was also a re-created Amiga chipset but the engineers had the original design chip schematics, something the developers today do not have.

I'd be surprised if anyone would disagree that it will be hell of a lot closer to the original hardware that we love than WinUAE

I disagree. :-P

Why doesn't WinUAE 'feel' like your original Amiga? I ran WinUAE on my Iiama Vision Master 450 Pro at 50Hz with VSYNC for many years and it felt very close. Could it be your setup? I used a monitor capable of an exact multiple of the Amiga framerate (50Hz, 60Hz, 100Hz) forced this using powerstrip and enabled VSYNC. This makes all the difference to me.

[Fats]

Whether or not you feel the result is emulation or not i don't feel like participating in again, though i do have my choice on that debate.

Nice thing about language is that it is not an exact science; even dictionaries are just a snap shot of the what a word means at a certain point in time. So you can claim all people in this thread are right, as well as they are all wrong . I just love reading these threads and they can go on forever...

All the best!

[psxphill]

Oh I see. So if you run an ECS game on an A1200, I guess that's emulation?

You're being too vague. What do you guess is emulation?
 
Going into the early boot menu and disabling the caches on your 68020 so it emulates the behaviour of a 68000, or setting the chipset to OCS so that it disables 32 bit fetches so that it emulates the OCS chipset more closely.
 
There is some emulation going on there, it's probably not what you think of as emulation.
 
Whether you use an a500, WinUAE or FPGA arcade. It's not going to look the same on a modern LCD as a 1084. I still use old commodore/philips monitors for this reason.

[gaula92]

As many have said, it is not emulation. It is re-creation. Like all re-creations how accurate it is depends in the information you have on the original.

AGA was also a re-created Amiga chipset but the engineers had the original design chip schematics, something the developers today do not have.


I disagree. :-P

Why doesn't WinUAE 'feel' like your original Amiga? I ran WinUAE on my Iiama Vision Master 450 Pro at 50Hz with VSYNC for many years and it felt very close. Could it be your setup? I used a monitor capable of an exact multiple of the Amiga framerate (50Hz, 60Hz, 100Hz) forced this using powerstrip and enabled VSYNC. This makes all the difference to me.

WinUAE runs under a deffective OS: it's software broken by definition.
-Running on a propietary closed-source OS means you depend on Micro**** to have a compatible OS.
-And more importantly: Windows is a broken OS, bloated an slow, wich you can't optimize much. There's no real way to ensure the defective OS won't take CPU from WinUAE to run any ****ty app in the background and cause desyncs, stalls or slowdowns. A real OS where you can configure and even modify scheduler is needed to avoid this broken emulation.
-Windows adds a lot of output delay.

It doesn't mind if you run on a 50Hz display. I did that on the past and you get smooth scroll etc, but it's a broken and immoral OS you're running under the hood anyway. It's NOT how an Amiga looks and feels.

Now an FPGA implementation IS an Amiga. It looks and feels exactly the same. Response is the same. It isn't a total and absurd waste of resources like WinUAE solution is.
WinUAE can be a tool for poor Windows slaves to work with HDF files and all that, but that souldn't be considered an Amiga Computer replacement. No way.

[cunnpole]

I disagree. :-P

Why doesn't WinUAE 'feel' like your original Amiga?

Consider me surprised

I'm not suggesting a dislike for WinUAE, but for me, it can be less immersive having windows getting in the way. A good Win7 setup helps a lot, but your millage may vary. I'd rather remove the OS from the equation and have a dedicated machine (but not in an AROS x86 way). It's like a temperamental 500W sledgehammer to crack a lemming shaped nut.

Back in the day I only had a 14" TV so it's more about the gameplay experience than the exact visuals.

The FPGA system also has other benefits: the wife doesn't like the amigas in the living room, because of all the space and cables. With this I can stick it to the back of the telly and just plug in joysticks as required.

[psxphill]

WinUAE runs under a deffective OS: it's software broken by definition.
-Running on a propietary closed-source OS means you depend on Micro**** to have a compatible OS.
-And more importantly: Windows is a broken OS, bloated an slow, wich you can't optimize much. There's no real way to ensure the defective OS won't take CPU from WinUAE to run any ****ty app in the background and cause desyncs, stalls or slowdowns. A real OS where you can configure and even modify scheduler is needed to avoid this broken emulation.
-Windows adds a lot of output delay.

Your argument became absurd when you changed Microsoft to put a swear word in.
 
Are you saying that UAE on Linux or MacOS is ok? In which case just don't run Windows.

[freqmax]

At least I know FreeBSD or Linux works better. But any multitasking especially non-realtime OS is going to produce a less responsive experience.

However an FPGA can produce accurate timing to most system components.

[persia]

UAE originated on Linux, it was ported to MS Windows.  Having an underlying OS doesn't really matter since you are emulating a system that doesn't have much CPU power.  I will give you that FPGA is a more efficient emulation, allowing for emulation on a much less powerful host, but is it going to be cheaper?

[freqmax]

The question is to ask:

Will it be more accurate?

What is the most sucessful way to do MFM decoding or that matter GCR from disc?
 * Write it in BASIC using INB .. on a single user system?
 * Write it in C using inb() on a multiuser system?
 * Write it in assemble using inb xx on a bare bones system?
 * Code it as an hardware description (HDL) equalient ?
 * Wirewrap it with 7400 circuits?
 * Etch an ASIC at horrendous cost?

Recall that these signals come at a synchronous specific time and doesn't wait for anything. And you need to listen to them with precision and act on them on time, all the time. There's also DRAM signals, bus responses, video generation, communication etc that all need the right response on time.
Add the complexity of several way more complicated circuits that all act in parallel with defined realtime responses. If you try to implement this on a single CPU system you will need to find out which signals that need hard realtime response and do a check-and respond to all those signals without ever delaying outside time boundaries. This means system response will be dependent on the total service loop execution time. A huge liability. The other liability  is that this signal servicing will not be in lock step with the system as a whole and thus introduce time jitter..
(a multi-CPU system makes this easier, but it still suffer from the same fundamental flaw)

When the possibility exist to model a signal system which is what the electrical circuitry really implement. The design thought process can focus on the modeling instead of explicit response times and time critical signal hooks. And when the model is correct it will "just work(tm)". Instead of having to figure out how to implement this as sequential code. So it is in the essence signal path description vs sequential code equalient.

As bonus that comes from being unimpeded by central clock phase, cache, logic bare bone etc one can interact with real hardware interfaces. A PC with a 2 GHz CPU should be able to respond to an I/O within 3 instructions so in the ballpark of 1.5 ns. But real life test rarely finds the parallel port respond faster than 1000 ns.

I hope this gives some understanding on the issues that FPGA/CPLD/7400 etc makes it possible to deal with efficiently.

[persia]

@freqmax

I get your point, but I would have used something other than a legacy port that doesn't exist on most modern computers to make it.  Your should be able to get better emulation faster and simpler through an FPGA system.  But in reality it's not going to make a difference to the vast majority of folks who just want to play old familiar games.

[freqmax]

I guess some games/demos just won't be themself in an environment that lack signal precision.

[persia]

I can see the idea of pulling the old dead motherboard out of an Amiga and sticking one of these in though.  These electronics are getting really really really past their use by date and some day they just aren't going to turn on again, better to have something that at least pretends to be an Amiga to stick into it.

[alexh]

WinUAE runs under a defective OS. Windows is a broken OS. it's a broken and immoral OS you're running under the hood anyway. It's NOT how an Amiga looks and feels.

I'm getting the feeling you don't like Windows?

Replace WinUAE with FS-UAE and re-read

It looks and feels exactly the same. Response is the same. It isn't a total and absurd waste of resources like WinUAE solution is.

Maybe a waste of resources but it is a hell of a lot cheaper! (P.S. They don't feel the same...)