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New development: GTIA in CPLD


Simius

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http://www.ebay.com/itm/altera-Mini-Usb-Blaster-Cable-For-CPLD-FPGA-NIOS-JTAG-Altera-Programmer-/200943750380

 

Including shipping, it's actually cheaper than the micro match connector :) Does take 3-5 weeks to be delivered though.

 

Yeah, hopefully Simius will release a few versions with different palettes. I don't mind the PAL palette (prefer it even), but I can imagine Americans want an NTSC palette because that's what they're used to.

Edited by ivop
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I was wondering why not just use the standard 10-pin IDC JTAG connector? The USB Blaster (which you need to update the firmware anyway) already includes with this cable. It seems Micro-Match connectors are not very common here in the U.S.

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a little disappointed to hear the colors are off (pink donkey kong / breakout/ pacman), specifically to 5200 because that's what I have ...but I believe this is how Sophia current works on all systems

 

Will additional color pallets be available some how?

 

I'm still confused because half the people here don't seem to think there's anything wrong with the colors.

 

I was wondering why not just use the standard 10-pin IDC JTAG connector? The USB Blaster (which you need to update the firmware anyway) already includes with this cable. It seems Micro-Match connectors are not very common here in the U.S.

I picked up both of these from DigiKey:

https://www.digikey.com/product-detail/en/te-connectivity-amp-connectors/1-215083-0/A107014CT-ND/3488575

https://www.digikey.com/product-detail/en/terasic-inc/P0302/P0302-ND/2003484

 

Can you defined, what means the "NTSC color profile"? Where is the pattern?

 

My apologies I guess I meant "palette" not "profile".

 

Simus -

It sounds like with your latest planned revision, we can now switch between palettes with a command. Awesome. However, this is not a viable option for Atari 5200 installs.

 

Is it possible to make a .pof file(s) available with a specific palette already set? This way 5200 owners can use whatever palette they like.

 

Don't get me wrong, this is an awesome product you've made, and the video quality is fantastic, I just want to get an accurate representation of what I'm used to seeing on my 5200.

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You misunderstood me. There will not be many palettes to choose, because the palette implementation isn't easy (it is made not as array, but by logic - Max II series hasn't fast enough, user flash memory) and there is to little resources to implement more than one. I can change the actual palette, but I'll not make many "user defined" versions. It have to be a common accepted pattern. There is several known palettes, which indicates that Atari color perception isn't uniform. For the reason of the potentiometer on board, TV/monitor properties, color system differences e.t.c. The datasheet definition is very poor. How to determine, which palette will satisfy everyone?

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I agree on the fact DK and PM colors are not good.

Maybe because those games were programmed with NTSC computers in mind?

I have to check my real PAL hardware to find out if Altirra palette is off or the games were made for NTSC not caring about PAL.

 

In general, I think PAL palette should be similar to real PAL hardware.

Otherwise software made for PAL hardware would have incorrect colors.

For example, Rastaconverter images made with PAL palette are not good on NTSC machines, and viceversa.

 

Only one palette, suitable for NTSC and PAL would be nice, but sometimes software is conceived for NTSC or PAL palette, not caring about the other palette.

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I would think that the idea is to be true to what either a PAL or NTSC system would look like in reality, and not to fix what was ill conceived in the original program. So in other words if something looked pink on PAL, but was brown on NTSC while using the original hardware in a factory setup machine, then that would be the target to shoot for. Two different video standards require two different palettes, not a one size fits all. Ideally to be compatible with both the 5200 and the computer series a jumper setting would be the most practical, or two different CPLD code sets if the CPLD doesn't have the room to store and/or switch between both palettes.

 

Am I far off base here, or does this make sense?

 

- Michael

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As promised, I checked my PAL Atari 800XL with s-video output.

It has exactly the same colors of Altirra PAL default palette.

Donkey Kong and Pac-Man on my real hardware are identical to the screenshots you posted.

 

So, I would like that my Sophia board reproduces exactly PAL colors (not NTSC colors) using Altirra PAL default palette.

I think NTSC friends would like that their Sophia boards reproduce exactly NTSC colors too.

Altirra is a fantastic emulator so I think its NTSC palette is accurate too.

I attach Altirra default PAL and NTSC palettes.

Altirra default palettes.zip

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I don't understand this - did Atari actually release Pac Man with different colors for NTSC and PAL? Aren't we just seeing the different interpretation of colors between the two, and if so, why isn't this simply rendered properly by the hardware or Altirra (ie DK and PM should look the way they did on the real hardware regardless)?

 

Pac Man dots are, and should always be yellow. Did PAL users actually live with those colors all their lives? :)

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That's the point I've been trying to make since the beginning.

 

It's obvious there's a significant difference between at least the two to warrant one PAL and one NTSC palette.

 

I understand that it's impossible to meet everyone's tastes. But I think making an alternative to reprogram to use an NTSC palette palette isn't much to ask for, given that the general consensus is that the Altirra NTSC default is palette is perfectly suitable.

 

If you really don't want to deal with it, then at least release something that would allow those of us interested to modify it to our own needs.

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I managed to implement both PAL and NTSC palettes (see attachment) that will automatically adapt to the current system.

 

 

Are you going to provide the new updated CPLD code that will implement these palettes in the Sophia hardware for those of us that already have the first run boards?

 

- Michael

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