MiSTer FPGA Forum

lordoftime79 wrote: ↑Mon Mar 29, 2021 5:00 pm so I am gonna show just how much I dont understand FPGA stuff now but cant the code be opened and the mhz section just be changed to a new higher speed?

There is no "code" .. and a FPGA has no master CPU like a raspberry Pi has, this is not like a software emulator that runs on a commodity CPU which on the fly translates every instruction executing on the guest (i.e. amiga 68 machine code) to its own op-code i.e. ARM on a Pi.. an fpga is just a chip with a bunch of undefined logic gates that do nothing until a gate map (aka "core") is loaded that tells the FPGA gates how to configure themselves.. much like etching silicon does with conventional chips.. unlike conventional silicon chips you can re-arrange these gate mappings as often as you like, with real silicon once its "etched" its unchanging for the rest of time..

Back in the days (mid 90ies) some fellow computer student friends and I concluded that the probably easiest and cheapest way for us to get faster Amigas, would be to use mind altering drugs that changed our own perception of time - maybe something to consider, hehe

throAU wrote: ↑Mon Mar 29, 2021 6:10 am sounds like what some people really want are 68k MMU and FPU. and if you’re running amigaOS both are mostly irrelevant.

Not really - FPU is supported and is used when available, by OS libraries.
But that is really beside the point, which is that there is plenty of SOFTWARE that not just use FPU, but sometimes require FPU.

If all you want to use AmigaOS for is to launch games, then sure, neither are of much use. But for many of us, that's not what this is about, we wish to run the same software we used to run on our old Amiga systems, and that includes also software that require FPU. My real Amiga systems always had FPU available, it used to be the cheapest upgrade possible (along with FastRAM), several Amiga systems shipped with FPU (and some that didn't still featured a spot ready on the montherboard, like A1200.)

unless you’re running amiga unix or linux i don’t believe the MMU is used anywhere?

Or NetBSD?

The MMU It is used here and there, but mostly for things that are irrelevant for MiSTer (overcome hardware issues, like initializing zorro3 DMA)

And Thomar Richter has been busy for years (decades?) with his MMULib package, that use MMU for many good and useful things (softkicking, copying kickstart to FastRAM and protecting it and lots more), but most of them again are not so relevant on "unreal" FPGA systems like MiSTer.

unless code is actually checking for an 030 somehow it should just run on simulated 020 unless it uses mmu. and if it doesn’t run, and performs some sort of check and doesn’t use the mmu all that is required is to lie to the OS.

From what I understand, the only way to detect which 68k CPU you have, is to throw code at it and see what sticks, so I don't think you can just lie
But I really don't know of any software that specifically require 68030 not just 68020.

simulated 040 is a different thing entirely and it has an extended instruction set

And that is a CPU that isn't really well supported by the OS... especially the FPU, which is disabled on boot and only activated by Setpatch via 68040.library, that emulates 68882 FPU instructions not found in the 68040... so that games can boot from floppy and not cause guru from checking for 68882

throAU wrote: ↑Tue Mar 30, 2021 12:33 am Just thinking outside the box (literally)...

What's the capability of the IO header on the DE10-Nano? It's fast/capable enough for SDRAM; would it be fast enough for a RAM+CPU board, like we used to have in trapdoor expansion for amiga 1200 and the like?

i.e., for those who really want a faster CPU in their simulated amiga, would it be feasible for one of those people to look at an expansion board with say DDR2-SDRAM and a PPC (or higher end 68k based - maybe ColfFire?) processor on it? I mention PPC as there are already physical PPC accelerators that exist for real hardware.

Hm, now you make me wonder... you don't have a MiSTer, do you?
You are not aware that the Minimig based core for MiSTer already can configure 384MB of FastRAM, that is DDR?

I'm sure real 68k CPUs must be cheap now?

Not really, they are getting hard to come by (which is why this FPGA stuff is a thing in the first place...), espeically 68060 are rare and expensive.

IIRC, the original Minimig box had a real 68k on it with FPGA custom chips only (or is my brain not remembering properly)?

Correct, Minimig v1.0 and v1.1 used/uses 68SEC000, the very last 68k that was in production. But Minimig is also more than 10 years away.

I mean just looking on mouser, a ColdFire physical processor is like $60... which I do not think would be cost prohibitive in itself if people genuinely want a faster, hardware based amiga. I mean if you want a real A3000/A4000 - just finding one is difficult and they go for stupid money, and are 30yo, etc.

https://au.mouser.com/Search/Refine?Keyword=MCF530X

Only the MCF5102 can potentially be used since it has extended 68040 code compatibility, the rest are very much incompatible with Amiga 68k software.

i.e., the custom chips, IO, etc. would be hosted via mister, the processor+RAM expansion would do most of the grunt work and access the chipset via the header? Obviously this would need re-work of the core to accommodate but would (I guess?) be less work that designing/testing/etc. a new CPU core?

Easiest path to fast CPU+FPU is to use software emulation on the ARM.

kolla wrote: ↑Tue Mar 30, 2021 7:38 am
Hm, now you make me wonder... you don't have a MiSTer, do you?
You are not aware that the Minimig based core for MiSTer already can configure 384MB of FastRAM, that is DDR?

Have a mister + 128 MB expansion and use it, including for minimig. Had a couple of real amigas in the past.

Maybe I should clarify my thinking (which may not be clear) behind putting the RAM and CPU on the same board: to enable VERY fast access to the hosted RAM from the add-on CPU without needing to go over the expansion IO to the DE10 - and use that purely for the custom chips implemented in the mister.

i.e., the CPU+RAM board has its own very fast ram via a local bus on the expansion board, and the Mister simply becomes an amiga chipset (or AAA or AAA+ or even more advanced no-yet-existing follow up amiga compatible chipset - but for now, AGA) accessed via the GPIO header - rather than the processor living in FPGA and accessing memory via the relatively slow GPIO header.

Just a thought experiment anyhow (hence, "thinking outside the box" - as in outside of the mister FPGA for a CPU upgrade ) - as many have said, I personally think that if you want a fast amiga just use WinUAE, and if you want to actually get work done with apps needing fast hardware, use a modern platform. Was thinking it may enable much faster than CPU emulation via the ARM HPS - because the ARM side in the mister is not particularly fast?

I do think if you want a super-fast "amiga" CPU, you probably want to go PPC anyway. There already exists add-on PPC accelerators, they've been around for real hardware for ages...

These threads sort of got me wondering. There is a lot of push-back against the ideas proposed here: FPU, MMU and faster clocks. The whole reason why I'd want any of these would be to open the platform up to more software and I'm quite aware that said software would be very much niche.

As it stands now, the MiSTer gives me a damn near perfect Amiga 500 for which I'm intensely grateful. I never owned anything faster than that myself so I can't really compare the AGA bits with any real systems.. but I'm guessing the A1200 is also fairly well covered by MiSTer these days.

Assuming that I'm not too far off the mark with the above, what else would the future development path of Amiga on MiSTer be if not the niches already described?

I thank you guys for educating me on how FPGA's work - this is all very interesting! So then why not replicate a buffee or PI storm and have a option in the core to use the ARM CPU to emulate the amiga CPU at a much faster speed (as thats what those projects do)

Bas wrote: ↑Tue Mar 30, 2021 10:10 am
As it stands now, the MiSTer gives me a damn near perfect Amiga 500 for which I'm intensely grateful. I never owned anything faster than that myself so I can't really compare the AGA bits with any real systems.. but I'm guessing the A1200 is also fairly well covered by MiSTer these days.

I used an A1200 a fair bit back when they were current and IMO the Mister is a comparable experience with faster CPU.

Compatibility with Mister is better than I remember with the A1200 hardware in fact, as it is trivial to simply boot a different configuration fairly fast (bearing in mind my A1200 was hard drive rather than booting from flash) rather than relying on relokick floppies or hardware switches to go back to kickstart 1.3, going into the boot menu to turn off the 68020 cache (non-original amiga users may not even know about holding down both mouse buttons on boot to access the equivalent of UEFI/BIOS on kickstart 3.x - which still works in Mister when using kickstart 2.x/3.x), etc.

Sure, the FPGA compatibility isn't perfect, but vs. using a real A1200 when they were released, there's far less quirks to deal with using Mister today than there was on real hardware in the early-mid 90s until/unless you used various work-arounds.

lordoftime79 wrote: ↑Tue Mar 30, 2021 11:02 am I thank you guys for educating me on how FPGA's work - this is all very interesting! So then why not replicate a buffee or PI storm and have a option in the core to use the ARM CPU to emulate the amiga CPU at a much faster speed (as thats what those projects do)

I think something like that is in the works .. but you didnt hear it from me and thats all I know about it.