FPGA for dummies

[psxphill]

You take the VHDL & it gets turned into an ASIC. I know how that works. Once you have the ASIC you run it when the clock starts. Running doesn't require a CPU style fetch execute mechanism, just a clock.
 
I understand whats going on physically in the FPGA and ASIC & it supports my argument about using an FPGA to recreate an Amiga is simulation/emulation.
 
I am not going to explain everything in minute detail, just so you can't find a way to purposefully misinterpret what I'm saying.
 
"It is difficult to get a man to understand something, when his salary depends upon his not understanding it" Upton Sinclair.

[HenryCase]

You take the VHDL & it gets turned into an ASIC. I know how that works.

Okay, explain it then. What is involved in that translation between VHDL and an ASIC? If you know how it works, then it won't be a problem explaining it. I await your reply.

[psxphill]

Okay, explain it then. What is involved in that translation between VHDL and an ASIC? If you know how it works, then it won't be a problem explaining it. I await your reply.

logic synthesis -> placement tool -> routing tool -> profit

[HenryCase]

logic synthesis -> placement tool -> routing tool -> profit

Good. So do you know how much work is required for those steps? The simplification you're implying is that tools do most of the work, whereas the reality is moving from FPGA to ASIC is a labour intensive process that makes use of tools to simplify where possible. There are reasons why ASICs take months to design, even with a working FPGA version in place.

In this process, VHDL is not much more than a design spec, you can use it to kick off the logic synthesis process, but beyond that it's not going to be an active factor. This is why saying an ASIC 'running' VHDL is a mistake, unless you're making some gross oversimplification that any description of an integrated circuit is a 'VHDL'.

[psxphill]

This is why saying an ASIC 'running' VHDL is a mistake, unless you're making some gross oversimplification that any description of an integrated circuit is a 'VHDL'.

You're suprised at gross oversimplification on an internet message board? While trivial in comparison I also don't mention creating a bitstream from VHDL and loading that into an FPGA.
 
The discussion was about whether using VHDL that described the behaviour of an Amiga to build an FPGA or an ASIC was simulation/emulation, the procedures you go through to do that are irrelevant to that discussion.
 
In the same way as how you simulate the amiga chipset is irrelevant, whether you're using software, hardware or pen & paper (this last one is labour intensive, slow & suffers from random innaccuracies and boredom).

[Thorham]

Good. So do you know how much work is required for those steps? The simplification you're implying is that tools do most of the work, whereas the reality is moving from FPGA to ASIC is a labour intensive process that makes use of tools to simplify where possible. There are reasons why ASICs take months to design, even with a working FPGA version in place.

Are you saying you can't implement an FPGA circuit design directly using an ASIC?

[HenryCase]

The discussion was about whether using VHDL that described the behaviour of an Amiga to build an FPGA or an ASIC was simulation/emulation, the procedures you go through to do that are irrelevant to that discussion.

Let's just put it like this, I'm surprised that you brought up VHDL in the same sentence as ASIC, as they are not related.

Are you saying you can't implement an FPGA circuit design directly using an ASIC?

It's not impossible, the issue is that you wouldn't want to. To understand why, need to know about logic elements/logic cells (often shortened to 'LE'). See here:
http://en.wikipedia.org/wiki/Field-programmable_gate_array#Architecture

FPGAs make certain compromises in order to be reprogrammable. Designing a function in an FPGA relies on use of these generic building blocks, whereas with ASICs you have the freedom to make a design more efficient by simplifying/optimising the circuitry used. So whilst you could build an ASIC that mirrored the design of an FPGA, you'd be losing out if you did.

Before you start on the 'so FPGAs are only emulations' schtick, the important point to note is that even though the designs are different, they can be functionally identical. Think about it like this, Sony brings out a TV using an FPGA to drive the circuitry. They then bring out a new model, which is the same as the old one in every way, except the FPGA is replaced with an ASIC. Is the later model an emulation of the first? No.

[freqmax]

One could exploit FPGA "floor planning" to accomplish some performance gains. On ASIC I guess it's all about floor planning..

[psxphill]

Before you start on the 'so FPGAs are only emulations' schtick, the important point to note is that even though the designs are different, they can be functionally identical. Think about it like this, Sony brings out a TV using an FPGA to drive the circuitry. They then bring out a new model, which is the same as the old one in every way, except the FPGA is replaced with an ASIC. Is the later model an emulation of the first? No.

If you design one circuit to work the same as another one then it is a simulation. When the company that made the original uses the same design but slightly modifies it (i.e. switches from an FPGA to an ASIC) then it's not.
 
The same way that IBM made IBM PC's and other companies produced IBM PC clones. The term clone doesn't refer to the circuit being a direct copy, only that the same software can run. In todays language it would be an emulation.
 
The expansion model no 1 is also simulation/emulation.
 
http://www.colecovision.dk/atari.htm

[freqmax]

Holy crap, all my AMD are emulating Intel

[ferrellsl]

Holy crap, all my AMD are emulating Intel

He (psxphill) just doesn't get it.  He's starting to sound like a broken record or a sick parrot on a pirate's shoulder sqwauking, "Braaak, FPGAs are simulations, FPGAs are simulations."

Just because my next door neighbor has the same floor plan as my home, doesn't make MY home a simulation in ANY respect.....same can be said for FPGAs or CPUs, etc......What the heck would it be simulating?  Simulating implies that something about it wouldn't be real and I can assure you that my house is just as real as my neighbor's house.  Both homes were built using the same plans and for the same purpose but by different contractors.  Same can be said for FPGA based solutions.  It isn't simulating anything.  It's preforming the same purpose and function as the original.  It's just being designed and built by someone other than the original designer.  No more, no less.  It doesn't matter if those plans were reverse engineered or if the architect had access to the original architects specifications.  Both homes (and computers) are real and not simulating ANYTHING.  An FPGA-based Amiga is just as real as an original classic Amiga.

[Thorham]

Simulating implies that something about it wouldn't be real

Emulation/simulation doesn't imply that it isn't real, after all, everything that exists is real.

An FPGA-based Amiga is just as real as an original classic Amiga.

Of course, but it's not an Amiga, it's an Amiga replica. Two different things (look at the classic sports car world, the same happens there).

[ferrellsl]

Emulation/simulation doesn't imply that it isn't real, after all, everything that exists is real.

Uhh, that was my point.  No need to restate the obvious.  So if it's real, it is not a simulation.

Of course, but it's not an Amiga, it's an Amiga replica. Two different things (look at the classic sports car world, the same happens there).

No kidding Sherlock.  So what are you trying to say? That we should resurrect Commodore Inc. along with it's dead executives before we can have classic re-makes?  That's absurd.  The only thing that is going to satisfy you and psxphill would be to find a long-lost hidden cache of classic Amigas (or Amiga components) in some forgotten bomb shelter.  News flash, Commodore isn't coming back, nor is the Amiga.  Replicas are as good as it will ever get, so get over it.

More than one FPGA expert in this forum has set you and psxphill straight, but you two insist on spreading dis-information and continue to argue.  Just let it go.....please!

[persia]

Both UAE and FPGA are real Amigas.  Now we can all be one happy family.

[Thorham]

So if it's real, it is not a simulation.

What I mean is that a simulation is something that's real simply because it exists.

No kidding Sherlock.  So what are you trying to say? That we should resurrect Commodore Inc. along with it's dead executives before we can have classic re-makes? That's absurd.

No, I'm not saying that at all, and yes, that would be absurd.

The only thing that is going to satisfy you and psxphill would be to find a long-lost hidden cache of classic Amigas (or Amiga components) in some forgotten bomb shelter.  News flash, Commodore isn't coming back, nor is the Amiga.

That would be most satisfactory to me, yes. The chance that a large cache of NOS Amigas will be found is of course quites slim, so I'm not counting on it.

Replicas are as good as it will ever get, so get over it.

And that's not good enough for me, only a true hardwired copy would be good enough. I simply see FPGA computers for what they are, FPGA computers, that in and of themselves provide us with a new and interesting alternative computer platform.

More than one FPGA expert in this forum has set you and psxphill straight, but you two insist on spreading dis-information and continue to argue.

I think I have accepted corrections about the technical details, and I have already explained it. The problem was that I was trying to argue a point using technical details thinking it would help. Of course it didn't, and I have already admitted this. How many times must I say that I got that wrong?

My point is about emulation in and of itself and what it can be applied to. For example, can it be applied to software in general? Same question can be asked about FPGAs (and as billt, one of the experts, has said, it's a gray area, and I like to add to that that this makes the question hard to answer).

As for an FPGA computer being an Amiga, it's not, it's an FPGA computer. How difficult is that to see? Then again, people call macs with MorphOS Amigas, hell, people will call peecees with Amiga stickers on them Amigas, while obviously they're not. Why insist on calling something an Amiga while it's not?

[HenryCase]

If you design one circuit to work the same as another one then it is a simulation.

So, in your opinion, in the Sony TV example I gave, the ASIC is a simulation of an FPGA? If so, then I put it to you that nearly every ASIC that has ever existed is a simulation. Heck, Amigas are just simulations of Lorraine. Who knew we were all using simulations after all!

When the company that made the original uses the same design but slightly modifies it (i.e. switches from an FPGA to an ASIC) then it's not.

Ah, I see, you realised you'd gone too far, so stuck in this caveat about it needing to be made by the original company. You're clutching at straws, seriously. Let's put it like this. Imagine Commodore went bankrupt after the A3000, and was bought by Atari. Atari then bring out a new Amiga model, the A1200. Does that now make the A1200 a simulation, whereas it wouldn't be if Commodore released it? I should point out that in this hypothetical situation, the Atari A1200 is absolutely identical to the Commodore A1200 we know today, apart from the company that made it.

The same way that IBM made IBM PC's and other companies produced IBM PC clones. The term clone doesn't refer to the circuit being a direct copy, only that the same software can run. In todays language it would be an emulation.

Your use of the term 'emulation' is very wooly. The only major difference between an IBM clone and an IBM PC is the company that assembles it. IBM don't make PCs any more, but if they did, think about this... IBM brings out a new desktop PC. I then build a PC for myself that uses the EXACT SAME PARTS as the IBM one. Is my computer emulating/simulating the IBM one?

I think where you're going wrong is that you're trying to stretch the term 'emulation' to encompass the term 'copy'. When it comes to computers, copying something is not the same as emulating something. Emulation has a specific meaning when it comes to computers, it means making one computer run programs from an incompatible one. Copying, on the other hand, is prevalent throughout computing. For example, if I copy a file (i.e. clone it), am I emulating the file? I'm sorry, but your definitions are not standing up to scrutiny.