FPGA for dummies

[billt]

To revive a year old thread, there is now an online simple class about FPGA chips that seems relevant to this. It does compare and contrast software running on a processor and hardware configuration of an FPGA, and talks some about how things work inside. I've finished 2 of 5 sessions now, and am enjoying it. (On another note, I've just finished a university course in Computer Architecture, also very enlightening and interesting stuff about the control logic of a processor)

http://university.eetimes.com/lecture-calendar.asp?cid=901#lecture_track_cgid_3

[Lurch]

So after reading the entire thread (Why I did that I don't know) I came to the below conclusion:

FPGA = Emulation/simulation
UAE = Emulation/simulation

So I'll stick with my classic hardware :-)

[JimS]

Hey, I just got an email from Xilinx yesterday announcing that their new Vivado web pack edition was available for download...

Lurch: If you'd read the thread accurately, you'd have learned that:
FPGA = Reimplimentation
UAE = Emulation.   ;-)

[kedawa]

Yeah, logic is logic.  As long as it isn't one computer simulating another, it isn't emulation.

[Linde]

FPGA is not emulation. It's the recreation of the physical chips under a reconfigurable chip.

Not really. If the setups were exact clones of the chip they intended to emulate, I might agree. As of now, for example an FPGA Amiga emulator are entirely different hardware setups that do (almost) the same thing as the original hardware, trying to emulate it as closely as possible.

I don't get why people somehow seem to think that FPGA/emulation are mutually exclusive.

[Linde]

Thirdly, some of the content you linked to uses other, more descriptive, terms to describe what's occurring, e.g. "FPGA-64 is a re-implementation of the Commodore-64 computer using reconfigurable logic chips." Re-implementation is a clearer way of describing the process being followed.

Unless you end up with the exact same configuration of gates, it's not a "re-implementation" in any sense that makes it distinguishable from "emulation". And really, a re-implementation of what? The hardware? Nope. FPGA-64 makes a particularly interesting example because its SID emulation is not anywhere close to how the real SIDs function. Hardware end-functionality? Nope, even if it's close or maybe even "getting there". End-user experience? Fuzzy, but have a look at the FPGA-64 changelog to get an idea of what bugs they've had to tackle to this day and ask yourself if it makes sense that they are somehow all magically weeded out by now.

The only ways to have these FPGA systems come close to the functionality of the systems they intend to emulate is either to try to get them into reproducible states in synch with the original systems and analyze the differences, or take a microscope to the chip surface.

One will make you insane, the other will not

[Linde]

Yeah, logic is logic.  As long as it isn't one computer simulating another, it isn't emulation.

And what makes you think that the internal logic of an FPGA Amiga "re-implementation" is anywhere near the original internal logic of the chips it intends to emulate? These are complex state machines and aren't trivial to implement and test. I'm sure the FPGA emulation magicians here are doing a great job by making qualified and well-informed design guesses based on information that exists about these chips, and black box testing them with the original chips, but I doubt they are making exact copies of them at a gate level.

[mikej]

And what makes you think that the internal logic of an FPGA Amiga "re-implementation" is anywhere near the original internal logic of the chips it intends to emulate? These are complex state machines and aren't trivial to implement and test. I'm sure the FPGA emulation magicians here are doing a great job by making qualified and well-informed design guesses based on information that exists about these chips, and black box testing them with the original chips, but I doubt they are making exact copies of them at a gate level.

Not exact, but fairly close actually.
The Amiga chipset is very low gate count by any modern standard, and it's pretty easy to work out how they would have implemented it in logic. Functional testing against the original chipset lets you check the design at cycle level. Going further it is possible to trace the original chip die and extract more complex functionality exactly.
/MikeJ

[psxphill]

I'm sure the FPGA emulation magicians here are doing a great job by making qualified and well-informed design guesses based on information that exists about these chips, and black box testing them with the original chips, but I doubt they are making exact copies of them at a gate level.

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.

[xyzzy]

So does that mean AGA chipset emulates ECS and ECS emulates OCS ?

[_ThEcRoW]

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.

No, it isn't emulation.

[psxphill]

No, it isn't emulation.

What do you think emulation is?

[bloodline]

So does that mean AGA chipset emulates ECS and ECS emulates OCS ?

Sure, why not!? Merry Christmas...

Bit fed up with the religious wars... If it's not the original implementation, it's emulating the functionality of the original.

Why is emulation a "dirty word"? It's not, it's the future... Now lets get down to the important job of improving the quality of these FPGAs Amiga chipset emulation

[xyzzy]

It was a rhetorical question but I agree, bring on the FPGAs!

[Linde]

No, it isn't emulation.

Care to explain your reasoning? This isn't a very constructive way to join a discussion.

[Linde]

So does that mean AGA chipset emulates ECS and ECS emulates OCS ?

Well, AGA certainly isn't OCS or ECS. It's compatible to some extent, but hey, whaddayaknow, some careless OCS/ECS programs won't work correctly with AGA unless you patch them because of low level incompatibilities. Whatever you call it, AGA itself is an extension of these designs.