DFB1 + Nova Falcon Graphicadapter...

[markus0321]

Thanks for the suggestions on the Tseng cards.
I changed all chips to "F" series but it didn't fix the problem.
Looking at my card, I noticed 4 jumpers JP1..JP4 next to the ICS2494 chip, one of them was soldered permanently.
I removed this jumper JP1 and after starting the artifacts died and now I have a good picture. :D

Could you please figure out how the jumpers are connected to the ICS chip? Specifically what does JP1 do?
I am guessing JP1 is connected to PIN12 of the ET4000 chip and probably to PIN4 (or 5) of the ICS ?!

JP1 on my card is connected to pin 12 of the Tseng chip and pin 8 of the ICS chip. Originally, it shorted both pins to ground.

[Wolfgang]

JP1 on my card is connected to pin 12 of the Tseng chip and pin 8 of the ICS chip. Originally, it shorted both pins to ground.

Yes. This is also a pin that influences the frequency selection. I am not a hardware expert, maybe somebody can shed some light on this.
My guess is: pin 12 (DTEAL) and pin 13 (DTEBL) are meant to be /OE for the video ram chips. That said, when these pins are connected to the FSx (frequency selection) inputs of the ICS chip, the frequency gets changed when a read occurs. Most ET4000 cards that I own do not have pins 12 and 13 connected at all.
I found cards where
- no pin is connected
- only one pin is connected
- both pins are connected
If they are connected, there seems to be no specific order. i.e. each card has its own way of selecting the appropriate frequency. It is really hard to find the right way to support a given card.

The T0, T1,...T8 naming convention of the Nova drivers are based on the cards supported by the original drivers. They are responsible for:

- the DAC control (this is partly solved by DAC sensing routines in my drivers)
- the frequencies supported
- the frequency selection method

This was the main motivation for my nVMG project. It contained (besides the traditional Tx support) a frequency detection routine that attempted several different methods to setup the frequencies. Once detected, the detected setup was stored in configuration files and then used by the driver.

[markus0321]

After changing this jumper, the picture is still ok. I have two more issues to solve.

1. I can't get more than 256 colors on my Tseng card. Is it a problem with the card, because in my PC I have the same problem with this card?

2. Too little amount of ST-RAM (4MB) is it possible to somehow convert the 16MB RAM extension so that it works with half the amount of RAM, then 8MB ST-RAM would be available?

[frank.lukas]

256 Colors max is normal I think, see the Datasheet of your RamDAC. For more Colors you need a card with a AT&T 49X 24bit RamDAC or something. The ATI MACH 32 or 64 can do more Colors.

4MB ST Ram is max with the Nova Falcon because the Atari Falcon can not be work with 10MB ST Ram max.

[markus0321]

256 Colors max is normal I think, see the Datasheet of your RamDAC. For more Colors you need a card with a AT&T 49X 24bit RamDAC or something. The ATI MACH 32 or 64 can do more Colors.

4MB ST Ram is max with the Nova Falcon because the Atari Falcon can not be work with 10MB ST Ram max.

Could it be this ATT20C490-80 chip and will Hicolor and Truecolor modes be available with it?
According to the datasheet, this DAC supports not only 6 but also 8 bit and I found a card with such a chip on eBay. I haven't found ATI cards or the prices are unacceptable for me :-(

[frank.lukas]

to consider is that not all cards work. I have one with AT&T DAC that doesn't work. All ET4000AX only have 1MB Video Ram, so 640x480 pixels are only possible with 16.7 million colors and the ET4000 is extremely slow with this color depth. So the best with the ET4000AX are 256 Colors.

An ATI MACH64 is still fast enough with 16.7 million colors. The card are rare and extremely expensive. Rarely saw any on Ebay for $800 up. And with the Nova Falcon 2MB Video Ram is the max. (2MB Video Ram 800x600 at 16,7M Colors max)

Ebay: 404039863996 and 204215630601 (little AT&T DAC and DRAM)

[markus0321]

Thank you for your advice.
In fact, not only TrueColor interests me, HiColor mode would be enough for me. I saw a Teng card with a SC11483CN converter and this is a DAC that supports 32768 colors (HiColor). Maybe such cards work at least in HiColor mode and 800x600 resolution? Or maybe it would be enough to change the DAC on my one that is already working? Have you tried doing such "transplants"? ;-)

[frank.lukas]

Replacing the DAC is useless. It depends on the connection between the ET4000AX, the DAC and the clock generator.

I can test the speed at 15/16bit Colors ...

[frank.lukas]

I have a ET4000 card with a AT&T DAC that will not work in the Nova Falcon Adapter !

AT&T_Karte läuft_nicht_mit_Nova_Falcon.jpg

Some Gembench 4.03 runs with 8bit, 15bit and 16bit colors depth ...

800_8bit.jpg

800_15bit.jpg

800_16bit.jpg

... the gembench display values are not that bad but VDI scroll and blitting values are only half as high or more less. It all feels a lot slower .

[markus0321]

Your photo card has ATT20C490 and according to the site
https://silicon-heaven.org/atari/nova/Falcon030/ET4000
only ATT20C491 is confirmed. ATT20C490 is "looking for datasheet!" I don't know what it actually means?

For me, 256 colors are enough to work, but I would like to be able to display photos from time to time, so that's why I'm asking about this hicolor mode.
On the Idek's website, the SC15025 DAC is still confirmed as 24bit. I ordered the SC15025CN version from Utsource (28 DIP instead of PLCC) I will try it, maybe it will work, if not, at least I will confirm that replacing the DAC itself is not enough.