FPGA for dummies

[JimS]

Using FPGAs makes it possible to develop hardware with the same sort of investment as software. Once you have a basic platform like the minimig, FPGAarcade Replay, or the Natami, you can redesign the hardware at will by "recompiling" the design and reloading. You're not tied down to obsolete hardware. The folk working on the AGA minimig and the Natami are optimising the CPU - something Motorola (Freescale) is unlikely to do, as well as updating the Amiga chipset.

[JimS]

An existing classic Amiga, probably not... The FPGA amigas are about recreating the existing Amiga hardware - with extensions - inside an FPGA chip. How well that works depends on the skill of the people doing the design. Frankly, it amazes me that it works at all, much less as well as it does. ;-)
You can add new hardware beyond what the the original spec defined.. then you have to have some sort of software... or the new hardware could emulate some existing classic hardware that already has software. The AGA amiga core has a "gfx card" built into it that's compatible with an existing workbench extension made for the cards used in "real amigas".

[JimS]

When I try to explain this to non-tech types, I mention the 100 in one project board I had as a kid. It was a pile of components mounted on a masonite board with springs on the leads. It also had a pile of wires.... put the wires in the right places and you could make all kinds of stuff... Multipliy by about a billion and you have an FPGA. ;-)

[JimS]

But if you tell the FPGA to create a gate, how does it do that?  What is the FPGAs actual method of creating a gate inside itself?  How does it remember that gate? What is actually going on at the physical level?  Surely there aren't a lot of nano-bots building and tearing down hardware inside the FPGA.

The gates and other logic elements are already there. The connections between them are what gets loaded to "wire up" whatever circuit the designer defines. Check out the first chapter of this http://www.xess.com/appnotes/FpgasNowWhatBook.pdf

[JimS]

I find this philosophical argument about Emulation vs Real hardware equity funny.

Either via a software emulator or an FPGA, there is a recreation of the original functionality of the old chips. Neither is more "real" than the other and both "emulate" (meaning: appear to be like the original hardware from a user and software perspective) the Amiga.

I've thought that this emulation vs "real" argument amusing at times as well. I'm more concerned about semantics here. There is a difference between the two, from the technical viewpoint. That has nothing to do with which is "better" or which is a "real Amiga".

For those unsure about FPGA chips, think of them as thousands of little 74xx chips in one package that can be connected anyway desired by software.

An FPGA allows a hardware designer to build his circuits in a single chip, rather than use lots of separate components all soldered together on a circuit board

I visualize the original Lorraine wire wrapped prototype here. ;-)

[JimS]

thread:
So lets build a x86pc core for the Replay, then run UAE on it. What's that... simulation or emulation. ;-)

[JimS]

You know, I rather think that's a fun idea

Reminds me of back when I worked in an Amiga store and showed off by running AmigaDOS, Mac 68k, and msDOS simultaneously.

[JimS]

That's a waste of time and money.  It defeats the entire purpose of the Replay board which is to inexpensively recreate in hardware the classic Amigas that are so hard to come by anymore these days.

Didya miss the smiley at the end of that comment? I was mocking the more pedantic folk in this thread... What do do when faced with a synthesized PC running an emulated computer.  OK, maybe not the funniest gag... but that's my emulated sense of humor. :-)

[JimS]

I do want to add that I'm very impressed with billt's patience here.  He's almost written a dissertation on FPGAs here.  Very unimpressed by those who insist on arguing with him.

Same here... I've been wanting to get one of the dev boards out there and learn some VHDL. So listening to people with actual real-world experience with the tech is helpful.

[JimS]

You're not saying it right: An FPGA provides the user with an environment which enables the user to implement electronic circuit designs without having to build a physical implementation for each design. That's why it's an emulation.

Sorry, couldn't help my self

Au Contraire, An FPGA gives the user an environment were the user *can* build a physical implementation of his design without all that tedious mucking about with a wire-wrap gun and a pile of chips. That's why it's not emulation.  

Sorry, coundn't resist either. ;-)

[JimS]

"Proper Amiga", "Real Amiga", "True Amiga", "The Real Thing".  Oh wait, that last one is from a Coca Cola commercial.:roflmao:

Why can't the fanatics that try to turn this into a holy religion realize that there is no ONE definition of what a "Real" Amiga is anymore. Not even between the most hard core fanatics can they agree what is accepted as a "Real Amiga" and what is labeled as "Clone", "Emulation", "Copy", "The Evil Destroyer of Amiga", etc.

The problem is that those fanatics have brought this "what is a real Amiga" notion into an argument where it doesn't belong. The original question was whether or not an FPGA implementation was "emulation". I maintain that something like UAE where one computer executes a software program to pretend to be another is "emulation". Replay and Minimig are hardware implementations, same as if you wired one by hand like the Lorraine prototype.
It's got nothing to do with the "realness", "accuracy" "quality" or "amiganess" of the project, simply the underlying technology used to do it.
Sheesh

[JimS]

This is the problem, you maintain that but it's incorrect. You don't need a CPU to emulate something. People emulate other peoples behaviour for instance and there is no CPU involved there.
 
So please find some other way to differentiate between the emulation you like and the emulation you don't like.

What are you smoking? Did I say anything about liking one over the other? Sounds more like you have the prejudice.

[JimS]

How does it sound like that? I've said on more than one occassion that I like both. It's obvious from my question that I like both.
 
Only by saying that software is emulation but fpga is not emulation does it sound like prejudice.

My only concern is to recognize the different technology in the two approaches. Software emulation is different from FPGA implementation. Has nothing to do with anything other than that. They are both ways to do an Amiga, or other things.  

Suppose for example we were talking about music players... You can have a casette player and a CD player. Both do the same thing, but in fundamentally different ways.

[JimS]

Using the FPGA isn't emulation argument then the CD player doesn't play music as it is converted from analogue to digital and then back to analogue, while the tape stores an analogue wave.
 
In reality they are both lossy audio storage & reproduction systems, but the loss is in different areas.
 

You make my point for me. ;-)

[JimS]

That's where you're wrong. As language evolves, words pick up new meanings for specific contexts. For example, with computing, you have a bunch of words that existed before modern computing, but that have specific meanings when applied to computers: kernel, shell, mouse, pipe, etc...

Not only that, but the word "computer" had a meaning before the electronic device was invented. It originally referred to a person who had the fun task of calculating by hand huge and tedious tables of math functions. (Sin Cos and such)