MIST - Atari ST / Amiga fpga CLONE

[Sykobee (Briggsy)]

You can connect a CRT to the VGA output, it doesn't have to be an LCD.

Yeah, but it will still be a CRT optimised for higher resolutions (narrower electron beam) and 60Hz or 72Hz scanning (phosphor decay rate).  It will be better than an LCD, but it won't be the same as the television-tube totin' CPC monitor.  And that's if it supports 50Hz.


I think today the best bet is to use a decent filter on the image being displayed to make it simulate being on the old CPC monitor.  In an FPGA this would mean you need to scan your video output as normal (6845+GA), but instead of a monitor signal you write the RGB to another block of FPGA-addressable memory (720x576x2 bytes in size, to support the CPC+ palette, maybe double-buffered), and then have a scaler to scale that image, and send it to the VGA port/DVI port in the higher resolution, filtered format.  You might even be able to do some funky stuff to turn the 50Hz signal into a 60Hz signal if required for compatibility.

[Bryce]

I was thinking more in the region of a Commodore 19xx monitor, which was optimised for 800x600 with a .28 - .31mm pitch. this will definitely give you the most realistic picture from a VGA output, but turn off any filters the MiST offers.

Bryce.

[Gryzor]

Yes, I know you can connect a CRT with VGA, but was referring to the most common setup option...


Here's what it looks like (scanlines can be set to off (of course) or three settings, 25, 50 and 75%, shown in the three similat pics):




http://imgur.com/a/vCJlK#0

[Bryce]

Yes, I know you can connect a CRT with VGA

My comment was meant for MrLou actually

Those screenshots look fine to me.

Bryce.

[mr_lou]

What about movement then?

E.g. Super Edge Grinder.

Will it scroll the level by as smooth as on a CRT?

[TFM]

Gentlemen, nothing will ever beat the CRT. As nothing will ever beat a real record.

[Gryzor]

Yes, I think we all agree with this one, this has been established in the past over and over again.

[redbox]

I was interested in this, but 200 EUR...?! Wow. Too much for me.

1040STs are on ebay for £50, Amigas are similar. Or alternatively a £50 mini-ITX board has enough horsepower for both emulators.

[Sykobee (Briggsy)]

I was interested in this, but 200 EUR...?! Wow. Too much for me.

1040STs are on ebay for £50, Amigas are similar. Or alternatively a £50 mini-ITX board has enough horsepower for both emulators.

The FPGA boards feel just like the hardware though. Emulators never do because they're trying to make the emulation fit inside another system with different refresh rates, etc.  Hence the "poor scrolling" issue.


One FPGA board can be an ST, (fast) Amiga, CPC, C64, arcade games, Spectrum (why?!) and more - once the implementations are written anyway. And you won't get the poor scrolling issue.

[Gryzor]

You can't even compare the FPGA with the real thing. The real thing is better - and takes up much, much more space. A mini ITX board does cost quite a little, then you have to add the case (with a much larger footprint than the FPGA), CPU/HDD/memory/whatever and suddenly the cost is not that low. You may as well stick with your PC in the end - really, no sense in getting a separate PC...


Well I don't think it can actually be judged in a "sensible" way. It's just that the FPGA feels, indeed, fantastic. Very geeky, very real. None of the emulator crap... And yes €200 is a lot, but as I said I'm not regretting it for a moment


Heh, as I was hitting "Post" Briggsy replied. Can't agree more mate! Btw, scrolling on the MiST has really no issues that I can discern.

PS MiST already has some arcade cores, apparently it's very easy to make those.

[TFM]

Well, I saw a lot of FPGA CPC emulators coming and going. And the first one, the C-One with CPC core seems to be still the only one which makes some sense. However it's PCB / chips are outdated and too expensive.

The idea of the CPCnG was great, but failed on hardware side due to the lack of hardware geeks - and also struggles in the team.

[mr_lou]

The FPGA boards feel just like the hardware though. Emulators never do because they're trying to make the emulation fit inside another system with different refresh rates, etc.  Hence the "poor scrolling" issue.

One FPGA board can be an ST, (fast) Amiga, CPC, C64, arcade games, Spectrum (why?!) and more - once the implementations are written anyway. And you won't get the poor scrolling issue.

Are you saying, that all CPC games will run as smooth on any screen you connect to the MIST, as they do on the real CPC + CRT screen? Edge Grinder will scroll by smoothly? Dead on Time will have just as smooth movement?

[Gryzor]

I'm not saying anything, have no idea There's no CPC core for MiST yet. What scrolling I've seen on the ST and the Amiga seemed perfect to me, though.

[TFM]

Well, there are better CRTs than the original ones for CPC or Plus, especially in these days. But as it was pointed out before, games have been developed for it. So I am happy to use the original. Of course a speccy port is not an good example, but look at games like Gryzor, Trantor and most of the Dinamic or Probe stuff.

[Sykobee (Briggsy)]

Are you saying, that all CPC games will run as smooth on any screen you connect to the MIST, as they do on the real CPC + CRT screen? Edge Grinder will scroll by smoothly? Dead on Time will have just as smooth movement?

Assuming that the FPGA implementation of the CPC is faithful to the hardware, it outputs a PAL signal or 50Hz VGA/DVI/HDMI signal, and the TV or monitor you have attached it to support 50Hz input, then yes, it should do that.


And if there are bugs in the implementation, they can be fixed at any point.

[Gryzor]

MiST outputs, at the moment, at 50Hz and 56Hz (ST core, I don't remember about the Amiga core). Since my monitor is fine with that, then...

[ralferoo]

Are you saying, that all CPC games will run as smooth on any screen you connect to the MIST, as they do on the real CPC + CRT screen? Edge Grinder will scroll by smoothly? Dead on Time will have just as smooth movement?

My CPC board outputs RGB SCART, so if you plug it into a real CRT TV, then yes it'll be identical output to a real CPC (although as if using the SCART lead rather than the blurry picture of an MP2).

I'm also planning to emulate the monitor repsonse to changing HSYNC in the FPGA so I can output a well formed signal that'll work with LCDs but emulate scrolling. The issue is that the PLLs in LCD monitors are designed for faster HSYNCs than older TVs so they react to the change in HSYNC phase faster than an old CRT would - they essentially have the same effect, just over a shorter time. But I've not made any progress on that as I've been busy working on the disk emulation (which is tricky!)

[Gryzor]

Niiiice!


Now, please, please PLEASE do a port for the MiST! (yeah, fat chance, I know, but it doesn't hurt to ask...