FPGA for dummies

[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.

[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.

[Linde]

em·u·late  
3. Computer Science To imitate the function of (another system), as by modifications to hardware or software that allow the imitating system to accept the same data, execute the same programs, and achieve the same results as the imitated system.

All right... So, only the very first Amiga prototype which successfully ran some software is the original. All other Amigas 1000, 500, 2000, 600, 1200.. etc ever produced are emulators. So everything is an emulator, and we can stop this stupid discussion about emulation that pops up every now and then. Hopefully it will let people enjoy new FPGA hardware without obnoxious comments.

Obnoxious comments? Do you feel like these facts (that are totally irrelevant from anything other than a technical perspective) impose on the experience of using these FPGA systems?

Oh, and no, I don't think your argument holds any water. In what way does it make sense to you?

[Linde]

I don't know if it's the sound, graphics or input that is delayed (well, the sound definitely is on my systems) in WinUAE (most likely all three) but I definitely lost an important sense of immediacy when using it instead of a real computer. Of course it has the benefits of scaling in raw processing power with your processor, and the amount of peripherals you can simply emulate, but other than that I can't see any reason to use a software emulator over a hardware one.

Apparently the input delay issue have improved with the last few releases, but I'll happily wait for the Replay board before I use anything other than my A1200 for Amiga stuff again.