New development: GTIA in CPLD

[jk40001]

Interested in 1 or 2.

[Simius]

Another nice addition would be the ability to half shift Gr. 10 pixels to the left so they match other modes. This is one of those mystery things that is rumoured to be possible on normal hardware but not yet verified.

 

I checked it out. Pixels of GR.10 are not shifted comparing to the other graphics.

[Synthpopalooza]

@ProWizard

Only through RGB. No impact on the composite.

 

@MytekControl

That's why I asked about component. I'll try to make it.

 

@Ricortes

The device uses a clock signal (3.54MHz or 3.58MHz) from MB as a base for x8 PLL multiplier.

 

@Synthpopalooza

1. Yes. Each shade is OR-ed with the COLBAK register. The device has the same property. If you write #01 to the COLBAK register, each shade will have the least significant bit set

2. No. You want to shift the pixel before decoding. I talk with Rybags about shifting it after.

3. Yes. Text color in hi-res is independent from the COLPF2.

4. Unfortunately, there is no address space for additional 7 color register and not enough resources in CPLD.

 

 

 

 

 

Good news as far as the hi-res color is concerned. This leads to all sorts of interesting possibilities insofar as scanline and flicker modes. Especially if artifacting comes into play, blending a different color onto the background can lead to all kinds of color combinations.

 

Insofar as PMG's, do the priority rules in Antic 4 also apply here when placing them on top of the different colored hi-res pixels?

[abbotkinneydude]

Hi Simius! I'd be especially interested in a SECAM version. Will take the PAL version as well (1 or 2 depending on pricing). Thank you.

[kenjennings]

Demo Video, please?

 

I'm good for one. If the price stays under USD $60, probably good for two.

[AtariNerd]

Others might have addressed this, but I'm not too technical. Is this additive? Might be a nice trick, if one could add a luminance layer along with the original color signal, even if it means holding one image, while mixing it with either signals from the add-on or from a seperate screen produced by the GTIA itself. You would be blending two screens, which might flicker more, though I guess there might be ways to reduce that, as well.

[rayik]

Interested if works in 5200

[Synthpopalooza]

Others might have addressed this, but I'm not too technical. Is this additive? Might be a nice trick, if one could add a luminance layer along with the original color signal, even if it means holding one image, while mixing it with either signals from the add-on or from a seperate screen produced by the GTIA itself. You would be blending two screens, which might flicker more, though I guess there might be ways to reduce that, as well.

 

 

I have played around with this a lot, in 2011 I wrote a series of programs called Interlace Character Editor (ICE) that does full frame font, screen, and mode switches to blend modes and increase color resolution in text modes. These modes are related to Super IRG (a doubled Antic 4 using only font changes), although they have the drawback of flickering more, especially on PAL Ataris. However, when used with a modern LCD TV with frame blending, or a monitor with a scan doubler, the flicker is eliminated.

 

To create what I have termed the DIN mode, you would want to cycle the display list from Antic 2 (Graphics 0) to Antic 4 (Graphics 12) every cycle. In addition, you must cycle the background color PF2 every cycle to ensure that the background color remains static ... when the screen shows Graphics 0 the BG color must be the same as COLBAK.

 

The real fun comes with PF1. With this new GTIA device, you can now set the chroma for the hi-res characters separately from the background in Antic 2, this allows for more color combinations possible in DIN mode, or any other ICE mode that relies on Graphics 0.

 

The other advantage, comes from the added luminances in non GTIA modes. It becomes possible to blend two colors every frame using 1/16th of a luminance, which will help reduce the flickering dramatically, especially if using the MIN mode (12+9) in monochrome settings, where you can get theoretically sharper black and white pictures.

Edited November 6, 2016 by Synthpopalooza

[Synthpopalooza]

OK, another technical question.

 

With this new device would it be possible to improve the GTIA output when setting the GTIA modes in Graphics modes 1 and 2?

 

As it stands now, when using the GTIA (modes 9 10 and 11) in these modes, screen codes 0-32 (the uppercase range) are invisible, and you get only 10 of the 16 colors in GTIA 9 and 11, and 7 of these in GTIA 10. Also, one of the ranges only lets you use 2 colors plus the BG. Ideally, it would be nice to at least be able to display the lower uppercase range, and make use of the PF0 and PF2 colors which are unavailable currently when setting GTIA 10 in Graphics 1 and 2.

[Mathy]

Hello guys

 

Would additional modes be possible? Like 640 x 240?

 

Sincerely

 

Mathy

[Synthpopalooza]

There might be a way using the SHIMC technique. Thus used cycling hires mode by register PF2 between magenta and yellow to induce a 1/2 hires pixel shift. Maybe if thus is done on the PF1 pixels it might have the same effect?

[tuf]

Sign me up for one when the pre-order happens!

[Simius]

There is no PAL/NTSC encoding here, so there is no shift between different colors. Additional modes is a matter for ANTIC, not for GTIA.

[Rybags]

A shift ability would be cool, that'd allow scrolling to 320 pixel accuracy. A half pixel shift would allow a sort of software generated 640 pixel mode though of course they'd still be 320 pixels thickness.

[+tf_hh]

The new CPLD solution is already working. Features:

The tests takes some time. The decision on the mass production depends on the interest.

 

I´m also interested.

 

One hint for a possible mass production version: It should be better to place the GTIA (the real one, which must be placed on the new PCB) at the top of the PCB. Simple reason: This arrangement or parts will not work well in a XL system (800 XL, 600 XL) when all may be full socketed. But when the socket for GTIA is at the top of the PCB, it will fit in all systems (XL, XE, XEG).

 

Jurgen

[zeruel85]

Really interested for using with the 5200!

[gearheadtocz]

I definitely want one for my 5200. Sign me up!

[haightc]

Put me down for one as well... My system is connected to a PVM, so this will be a nice upgrade for me!

[iCach0]

I'm definitively interested, very happy to see this is in progress

[chadwyk]

Sweet! Came here by way of RetroRGB. I am interested in this if it works on the 5200!

[8bitbill]

Put me down as interested as well.

Thanks.

[twoquickcapri]

I would be interested in 2.

[funkwad]

Definitely interested RGB for 5200 - yaayy!

[ndary]

i Visited Simius last weekend and recorded a video of his new RGB upgrade, you can see it here:

https://www.youtube.com/watch?v=DOdKovvFvzU&feature=youtu.be

 

anyone volunteer to lend Simius a 5200 unit so we can make adaptation and test his RGB upgrade on that system as well?

there are no 5200 units in Poland.

 

Nir

[+Philsan]

Interested!