New minimig core for the MIST

[christianlucio]

For everyone interested, there is a new minimig core for the MIST, date 09.02.2020 with further improvements. I would like to see infos about experiences of other minimig users on the MIST. Looking forward to any comments and discussion.

[Solskogen]

I use it with two 4GB hard drive images (PFS3) with 3.1.4.1, BestWB and WHDLoad. Works like a charm!

[dreadnought]

So could you confirm it's cycle-accurate?

[robinsonb5]

Originally Posted by dreadnought

So could you confirm it's cycle-accurate?

No, it's not cycle-accurate - it just includes some recent bugfixes to the TG68K CPU core.

[christianlucio]

Originally Posted by robinsonb5

No, it's not cycle-accurate - it just includes some recent bugfixes to the TG68K CPU core.

I always thought that an fpga is most cycle accurate except the display section because of the VGA Output ?

[robinsonb5]

Originally Posted by christianlucio

I always thought that an fpga is most cycle accurate except the display section because of the VGA Output ?

It can be if the core's designed to be cycle accurate. There is a cycle-accurate MC68000 core called FX68 - and the Mistery Atari ST core uses it. (The Amiga's much less sensitive to cycle-accuracy thanks to the custom chips - ST software sometimes uses the CPU to do things the Amiga would do with the copper - which require very precise timing. if the CPU timing is "wrong" then the effect falls apart.)


The TG68K CPU used by Minimig was never intended to be a cycle-accurate replica of the MC68000 - just a CPU that's capable of running MC68000 (and 020) software - and in many cases its significantly quicker than the original.

[dreadnought]

The reason I ask is because the lack of this feature causes problems on RPi/Amiberry. Some games (eg Barbarian) run too fast (not intentionally), making them unplayable.

[christianlucio]

Originally Posted by dreadnought

The reason I ask is because the lack of this feature causes problems on RPi/Amiberry. Some games (eg Barbarian) run too fast (not intentionally), making them unplayable.

I have tried dozens of games the last 2 years and did not see one that runs to fast, so I think this is not a major issue here, if at all.Even demos that for example requires cycle exact cpu emulation on WINUAE like "100 most remembered 64 tunes" works on MIST.

[dreadnought]

It could be hard to tell perhaps in some games or demos, especially if you don't know about it and are not comparing against the real thing.

Try Barbarian, it's instantly visible. Or It Came From The Desert - intro, conversations and some action sequences are much faster.

[christianlucio]

Originally Posted by dreadnought

It could be hard to tell perhaps in some games or demos, especially if you don't know about it and are not comparing against the real thing.

Try Barbarian, it's instantly visible. Or It Came From The Desert - intro, conversations and some action sequences are much faster.

I tried Barbarian (Palace) but saw no difference to my Amiga 500; could it be that you have enabled one of the turbo-modes available in the minimig core ?

[dreadnought]

No, I was talking about Raspberry Pi. The explanation for these speedups there was that it's the lack of cycle-accurate feature. But I'm interestted in buying MiSTer, hence my questions.

Perhaps the FPGA boards/cores compensate for it somehow. Could you try It Came From The Desert as well, see how it behaves?

[robinsonb5]

Originally Posted by dreadnought

No, I was talking about Raspberry Pi. The explanation for these speedups there was that it's the lack of cycle-accurate feature. But I'm interestted in buying MiSTer, hence my questions.

Bear in mind that while the MiST and MiSTer are related projects, they're not the same thing - and while I wouldn't expect the MiSTer's Minimig core to behave wildly differently, this thread has been about the latest MiST Minimig core.

Perhaps the FPGA boards/cores compensate for it somehow.

It's probably because when configured without Fast RAM the memory timings are roughly correct on the Minimig core; the CPU can't run too far ahead if its having to wait for the chipset accessing memory like it would be on the real thing.

[dreadnought]

Originally Posted by robinsonb5

Bear in mind that while the MiST and MiSTer are related projects, they're not the same thing - and while I wouldn't expect the MiSTer's Minimig core to behave wildly differently, this thread has been about the latest MiST Minimig core.

It's ok, I'm just interested in these boards in general. As you say I suppose these cores are pretty much behaving the same way anyway, especially in regard to this problem (which I replicated using WinUAE on my PC btw).

It's good to know that MiST development is still active though. If it was cheaper I'd've probably gotten it already, but around here it costs ~200 pounds (Lotharek) so not that much less than MiSTer.