MiSTer FPGA Forum

Posted: **Fri Jun 10, 2022 3:56 am**

@rhester72

That's certainly above my pay-grade. I'm barely a software guy any more, though I have a grasp of gate layout and pipelining on the hardware end. If I had to do an MMU on an FPGA, I'd probably just do like the Apollo Team have done with their Memory Protection Unit.

I think it's a pity that the Open Innovation Network requires Linux to be incorporated in the end-product to gain access to more modern patents. A much better CPU than the AC68080 would be possible using instruction cracking. Maybe optimized CHK and CHK2 opcodes could be used to implement the Memory Protection Unit just by injecting implicit operations into the micro-op stream and bypass the page size requirements of a traditional MMU.

Posted: **Fri Jun 10, 2022 4:12 am**

Well, I was referring to the '030 MMU specifically because that unlocks a lot of fun stuff (full Enforcer, AUX, virtual memory) that can't be done any other way. I'm still a bit lost with the fascination of pushing Motorola instruction set performance boundaries when there's VERY good odds that the machine you're using to do the FPGA development is many orders of magnitude more performant than a fantasy CPU nobody will ever target possibly could be, but that's just me. Amiga is interesting for what it _was_...what it *could* be, as I see it, is well evidenced in the Raspberry Pi itself as a hobbyist construct.

Posted: **Sun Jun 12, 2022 7:04 pm**

I found another reason to get a 030 or 040 CPU on the MiSTer... seems The Settlers can only be played with map size 8 if you have an 030 or 040 CPU.

Of course, you could play it with map size 8 in the AO486 core, but I do think some prefer the Amiga version of the game.

Posted: **Mon Jun 13, 2022 3:25 am**

040 would be great for 060 games/demos. While I'm fortunate enough to have a TF1260 with a rev6 cpu, those are about as easy to find as unobtainium.

Posted: **Mon Jun 13, 2022 7:11 pm**

Caldor wrote: ↑Sun Jun 12, 2022 7:04 pm I found another reason to get a 030 or 040 CPU on the MiSTer... seems The Settlers can only be played with map size 8 if you have an 030 or 040 CPU.

Of course, you could play it with map size 8 in the AO486 core, but I do think some prefer the Amiga version of the game.

There used to be an Aminet patch that you could run in User-Startup that would allow an '020 to respond as an EC030 that was useful for (brain-dead) stuff like this. Or you could just patch a single byte in the game where the check is done. *shrugs*

Posted: **Tue Jun 14, 2022 6:35 am**

rhester72 wrote: ↑Mon Jun 13, 2022 7:11 pm
Caldor wrote: ↑Sun Jun 12, 2022 7:04 pm I found another reason to get a 030 or 040 CPU on the MiSTer... seems The Settlers can only be played with map size 8 if you have an 030 or 040 CPU.

Of course, you could play it with map size 8 in the AO486 core, but I do think some prefer the Amiga version of the game.
There used to be an Aminet patch that you could run in User-Startup that would allow an '020 to respond as an EC030 that was useful for (brain-dead) stuff like this. Or you could just patch a single byte in the game where the check is done. *shrugs*

Yeah, I have been thinking that it ought to be possible to just patch the game. The 020 in the MiSTer Minimig core should be more than fast enough, and I highly doubt the problem is the game actually needs 030 or 040 instructions to be able to do map-size 8.

Anyone tried forcing a map size 8 maybe? I thought about using a map editor, or maybe just using WinUAE, load a game with a large enough map, save the game and see if it loads on the 020 after a reboot. I suspect they might not have added a check for this with the savegames.

Posted: **Tue Jun 14, 2022 8:01 am**

rhester72 wrote: ↑Mon Jun 13, 2022 7:11 pm There used to be an Aminet patch that you could run in User-Startup that would allow an '020 to respond as an EC030 that was useful for (brain-dead) stuff like this. Or you could just patch a single byte in the game where the check is done. *shrugs*

Would you happen to know the name of that tool? Did a quick search of Aminet, but couldn’t find it.

Posted: **Tue Jun 14, 2022 2:41 pm**

limi wrote: ↑Tue Jun 14, 2022 8:01 am
rhester72 wrote: ↑Mon Jun 13, 2022 7:11 pm There used to be an Aminet patch that you could run in User-Startup that would allow an '020 to respond as an EC030 that was useful for (brain-dead) stuff like this. Or you could just patch a single byte in the game where the check is done. *shrugs*
Would you happen to know the name of that tool? Did a quick search of Aminet, but couldn’t find it.

No...it's literally been decades since I last used it. I'll see if I can find it again. I thought it was Aminet, but it's _possible_ it was on a Fish disk, probably worth looking there as well. It didn't do much at all besides live-patching the chip ID when queried.

Posted: **Tue Jun 14, 2022 3:03 pm**

Now I need to know... I'll whip up a tool that patches exec.library and see what The Settlers thinks of it.

Posted: **Tue Jun 14, 2022 8:24 pm**

Did some tests and unfortunately WHDLoad crashes when execbase->attnflags is set to anything higher than the actual CPU. Contacting the slave author (or anyone else who might be up to the task) about patching away the CPU type restriction on maximum map size is the better way to accomplish this...

Posted: **Wed Jun 15, 2022 7:34 am**

Malor wrote: ↑Sat Apr 30, 2022 12:57 am But with a faster CPU, that would be less true. Perhaps nobody will actually do one, but quite a few software packages would benefit from a faster CPU. For example, one that seemed to benefit from all the CPU you could scare up was Stunt Car Racer, and the Amiga version of that game is the best one.

It seems very weird to me to criticize wanting more CPU on Minimig. It may not happen, but it doesn't seem weird to me to want it.

Not really criticising, more explaining why development effort (and it will be significant) is likely focused elsewhere. If someone wants to take up the challenge and do it, more power to them! But expecting others to prioritise this is unrealistic because of the limited payoff.

I'd love the MiSTer to do everything as well, but in terms of return on effort invested it's way down the list vs. something that will have more relevance to more people.

Posted: **Thu Aug 15, 2024 6:47 pm**

Another reason for a 68030 with MMU: https://github.com/dplanitzer/Serena

Posted: **Sat Aug 17, 2024 8:35 pm**

I'm not sure obscure, never-existed-contemporarily-with-the-hardware operating systems necessarily falls into the "reason" bucket. =)

Posted: **Sun Aug 18, 2024 9:06 am**

A proper 68030 would open more than just big box Amiga. Atari Falcon and bigger Macs would come much closer as well.

Posted: **Mon Aug 19, 2024 6:35 am**

Bas wrote: ↑Sun Aug 18, 2024 9:06 am
A proper 68030 would open more than just big box Amiga. Atari Falcon and bigger Macs would come much closer as well.

NeXT machines too..

Posted: **Mon Aug 19, 2024 10:15 am**

FYI, you can already run NeXT on the SparcStation core.

Posted: **Mon Aug 19, 2024 12:45 pm**

Yes but it’s not a next it’s a previous

Posted: **Mon Aug 19, 2024 1:39 pm**

rhester72 wrote: ↑Sat Aug 17, 2024 8:35 pm
I'm not sure obscure, never-existed-contemporarily-with-the-hardware operating systems necessarily falls into the "reason" bucket. =)

It's definitely a reason - it opens up this sort of thing, along with running Linux on the Amiga core.
There are a lot of people who want to do things because they can, not because there's any good reason to do so.
Opening up the obscure to the MiSTer audience isn't a bad thing (if it was there are a lot of cores which wouldn't exist)

A full 68030 is definitely useful for contemporary Amiga software - but that's already a well-covered obvious use-case.

Posted: **Tue Aug 20, 2024 6:25 am**

limi wrote: ↑Mon Aug 19, 2024 10:15 am
FYI, you can already run NeXT on the SparcStation core.

ill have to look into this.. thanks! Still would be nice for all the OTHER reasons stated to have something beyond the 020

Posted: **Tue Sep 24, 2024 12:43 pm**

I'd love a 68040 without the FPU. A bunch of old Macintosh 7/8 systems could use it. E.g a Performa 650. FPU would be cool to have, but not necessary for a bunch of software I currently want to use which can't run on MISTer in it's current form.

Posted: **Tue Sep 24, 2024 2:47 pm**

I'd like to just get any form of color Mac first. LOL

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