RGB2VGA: customizing a GBS-8200 for a cleaner low-lag image

[+Stephen]

Wow - you're trying really hard to make me not use my PVM aren't you This will make it SO much easier to demo the 1088.  Man - now all we need is someone to find the original case moulds and make clear 1050 cases.

[+mytek]

3 hours ago, Stephen said:

Wow - you're trying really hard to make me not use my PVM aren't you This will make it SO much easier to demo the 1088.  Man - now all we need is someone to find the original case moulds and make clear 1050 cases.

Your PVM still has it's uses, since the VGA output will not currently render interlaced images correctly, so things like FlickerTerm will not look right. Not sure if this can be resolved appropriately via different GBS presets, but presently its beyond my ability to know. However with the firmware source code being in the public domain, much smarter minds than mine can have a stab at it. Luckily the percentage of programs that use the interlace trickery, are far and few between.

 

With the dual video buffering, you will still be able to keep your PVM connected at the same time as whatever VGA monitor you may be using. So for those rare occasions when the VGA isn't able to render something, you can easily fall back on the PVM.

 

Edit: I'm all for a clear case ? .

 

[+mytek]

13 hours ago, wildstar87 said:

What program is it that shows those color bars?

It's something I wrote in Basic back in the 80's.

 

Here's an autoloading ATR using Turbo Basic to run it (it's a bit faster to render the chart, although still slow compared to ML): Color Bar Chart.atr

 

[wildstar87]

Mr Robot

 

I'm still fiddling with the VBXE color issues, and it really seems it's more the VBXE than the GBS-8200 at this point.  I'm trying to figure out what the "default" color palette output should be.  It may be that the PAL color palette that the VBXE outputs is just what I'm seeing, but I have no idea, as I have no other examples to see, and pictures will always be affected by camera white balance and display monitor.

 

I did connect it to a Sony PVM monitor with RGB inputs, at my work, I'm getting the same results, I would actually say greener than the GBS board.  I've gone through the settings, tried different color temp settings in the monitor, nothing really changed.  I also tried the color pot last night, as I suspected, it had no effect on the VBXE colors.

 

Can I ask what colors you see out put from the VBXE on your setup?  I'm assuming you are getting a blue background for dos, can you check Star Raiders, to see what color you see when you turn on the shields? 

 

Here is a video showing a blue shield (What I see UAV to CRT): https://youtu.be/V_dA8dkN4Qk?t=69

 

Here is a video showing a green shield (What I see VBXE to CRT/LCD, also notice the purple "red alert"): https://youtu.be/3_VDM8nC9sM?t=14

 

No idea what setups the machines were in these two videos, if they were real hardware, or just emulated.  But it gives you an idea of what I am seeing, on CRT, and from VBXE.

 

I will be trying the GBS-Control custom firmware/hardware to see if that makes any difference with some of my issues, though that is a bit of a tangent from this particular thread.

 

[flashjazzcat]

VBXE uses the laoo palette, IIRC, and this will look identical (i.e. 'PAL') regardless of whether the machine is PAL or NTSC.

[Mr Robot]

@wildstar87 I will grab the program on post 4 and take a screenshot today, that will give to something you can run and compare with.

 

Sophia users have the same issues with output colors btw

 

[flashjazzcat]

1 hour ago, Mr Robot said:

Sophia users have the same issues with output colors btw

I did not get that impression from this machine:

 

 

(Start at 15:38)

[+mytek]

3 hours ago, Mr Robot said:

Sophia users have the same issues with output colors btw

I also didn't get this impression with any of the Sophia RGB boards I've worked with, other than the initial yellow text problem that got resolved early on. When compared next to S-Video, the colors look the same in either PAL or NTSC, other than the usual differences in each that we always see. This seems to hold true whether I use an RGB monitor or VGA through the GBS-8200 with the replaced presets and the trim pots all fully CCW.

 

Now the last time I was testing with the Sophia DVI board, I was seeing some issues with the colors being slightly off, but I forget whether that was in PAL or NTSC.

 

[wildstar87]

Thanks Mr Robot, I have tried to run that, but I'm not having luck, but I'm fairly sure it's how I'm trying to run it, and I just haven't had time to sit down and monkey with it.  I would still like to know your feedback on Star Raiders colors.  No one has said it outright, but I'm getting the impression that the PAL color palette is indeed responsible for the differences I'm seeing, so Star Raiders in PAL would be the colors that I'm seeing, Green Shields instead of Blue, and a Blue-Green dos screen, instead of Blue dos screen?  I'm wholly unfamiliar with PAL, since I've only used NTSC versions.  My impression with Sophia was that it was still closer to NTSC than what I'm seeing with VBXE, because I noticed an immediate difference in color after installing VBXE.  Tracking down whether it was the GBS-8200 or VBXE has been my issue since, but the Sony PVM monitor was also very Green so that's been narrowed to the VBXE. 

[Mr Robot]

Here's NTSC 800XL UAV S-Video through an Amberry converter to VGA

 

 

Here's PAL 1088XEL VBXE RGB

 

Here they are side by side

 

Here's Atari800 4.1.0 Full NTSC filter

 

Heres Atari800 PAL Accurate PAL Blending

 

 

That's all I got!

 

 

[Mr Robot]

10 hours ago, flashjazzcat said:

I did not get that impression from this machine

 

8 hours ago, mytek said:

I also didn't get this impression with any of the Sophia RGB boards I've worked with

 

 

I'm happy to just say OK, my bad, I remember seeing discussion about the colours being wrong, could have been really old discussion though. I don't have a Sophia to say for sure

[+mytek]

1 hour ago, Mr Robot said:

I'm happy to just say OK, my bad, I remember seeing discussion about the colours being wrong, could have been really old discussion though. I don't have a Sophia to say for sure

No worries .

 

When the first Sophia's were being sold, they had an extra color available as discussed here...

Because of the incompatibility issues, the CPLD code was changed so that the default mode better represented the colors you would normally expect from a stock Atari. I believe there were also some palette changes that followed, but I'm not 100% positive about that aspect.

 

Anyway a Sophia that was recently purchased will match pretty darn closely with the stock video colors.

 

[+mytek]

Here's the complete RGB2VGA-XLD project: RGB2VGA-XLD Project.zip

 

This includes:

• Updated schematics which also incorporate BOMs.
• Updated PIC GBSCTRL firmware (version 1.1) source, hex, and JOY2PIC flasher.
• Gerber files for PCB manufacture.
• Installation Photos

One item that isn't covered, but will be required, is the interconnect cable between the RGB2VGA-XLD and the VGA2GBS-CONN boards. It's something I purchased off of eBay for pretty cheap, and is described as: Male & Female Micro JST 2.0 PH 8-Pin Connector plug w/Wires Cables. It comes terminated on one end with the connector that mates with the VGA header on the GBS-8200, and the other end is non-terminated. A Dupont style 8-pin female header with terminals will be needed and crimped on the wires once they are cut to length (5").

 

 

The wire order is pretty straight forward as can be seen in the photo above (basically a one-to-one arrangement).

 

The size of the main board is far too large to get a decent deal on OSH Park, so my recommendation would be to use JLCPCB instead.

 

Eventually I'll set up a page on my website about this project, and provide the file download from there as well . As for the projects completeness... I presently don't have a VBXE, so I'm unable to really fine tune the higher resolution modes without it. Eventually I hope to rectify this problem, but that'll have to wait until another day when I have an extra $100+ lying around, and the free time to play with it. However the Sophia RGB video board works beautifully in either NTSC or PAL using the low resolution modes. Since the source code has been provided, anyone can feel free to improve upon it. I've done the hard work already .

 

This is a public domain release, so anyone is free to build, modify, and sell it.

 

EDIT: There is one known glitch relating to using the JOY2PIC to program the PIC in-circuit. It won't work, since the added video amps on the common power connection draw too much current for the JOY2PIC to supply, so the chip will have to be flashed out of circuit instead. However the ICSP method still works just fine with something like the Microchip PICkit series or its clones.

 

EDIT2: I discovered the real reason for the excessive power drain. The video amp chips are only rated for a 3.3V supply. Since they share VCC with the PIC12F1572, they present a major clamping effect when being forced fed 5V from the JOY2PIC. Luckily the JOY2PIC's 5V has some inherent current limiting, so no damage was done. However I wouldn't recommend trying this. The PICkit series programmers have voltage and current sensing so they automatically turn the supplied VCC down to 3.3V, and are able to re-flash the chip in-circuit without issue. Previous statement not true. The video amplifiers can run from up to a 5.5V power supply. They're just too much load for the VCC output of the JOY2PIC to supply. The RGB2VGA-XLD schematic has been updated with this information on 12/6/2019.

 

Edited December 8, 2019 by mytek
Added note about ICSP and the JOY2PIC

[Dropcheck]

Hi Michael,

 

    I can loan you my VBXE.  I still haven't found the time to install it in my 1088XLD yet.

[+mytek]

5 hours ago, Dropcheck said:

I can loan you my VBXE.  I still haven't found the time to install it in my 1088XLD yet.

That's awfully extremely nice of you, but to be truthful I'm just not in the mood to want to fiddle with one at this time. With this project wrapping up, I find myself feeling like pursuing other things for a while.

 

Thanks anyway .

 

Edited December 6, 2019 by mytek
Better choice of words

[+mytek]

A new Web page has been created that covers this project: https://ataribits.weebly.com/rgb2vga-xld.html

 

Its nice to have a central resource for everything related to this now that its in a finished state, instead of weeding through the multiple pages in this topic .

 

There was a recent change to the GBSCTRL firmware which is available on that page. Its now at version 1.2, and continues the trend towards making things a bit better visually. I highly recommend updating to this new version, and giving it a try.

 

Here it is so that you don't have to go anywhere else to get it: gbsctrl_v1_2.zip

 

Edit: still tweaking things on the webpage to get the layout working better in a reduced browser window size, so expect a few querks over the next couple of days until that gets ironed out.

[chevymad]

I've got a vbxe and gbs8200 on the way now for my XEL. Is there a clear set of instructions for what I need and need to do anywhere for this combo? Anybody have a set of boards that I'd need? 

[+mytek]

16 hours ago, chevymad said:

I've got a vbxe and gbs8200 on the way now for my XEL. Is there a clear set of instructions for what I need and need to do anywhere for this combo? Anybody have a set of boards that I'd need? 

The link provided in the post I made previous to yours has quite a bit of info about the boards, gerber files for manufacture, and a schematic with a BOM on the 2nd page. The documentation is all at a very basic DIY level, but perhaps not as detailed as what you are looking for. Nobody that I know of are presently manufacturing complete assemblies. And although the GBSCTRL firmware works quite well for something like the Sophia, I can't verify if it works well for all possible video modes that a VBXE is capable of. However since there is full source code provided, future updates are always possible.

 

Please keep in mind that all of my projects should be considered experimental in nature, and I make no claims that it is ready for prime time, nor take any responsibility it if is not. If someone has decided to manufacture and sell any products based on my designs, I assume that they have tested it and found it suitable for distribution.

 

Edit: Just realized you said XEL not XLD. There are no instructions specific to putting this into that system. First of all I would imagine it would be quite a challenge finding the necessary space for the GBS-8200. But if that can be figured out, then minimally you might want to use the GBS-PGM board which piggybacks on top, and perhaps also look at the VGA connector board as a possibility to get the VGA out of the case. Both of these boards are shown on that linked page.

 

 

[chevymad]

Thanks for the reply. And I know this is all a bit experimental and is actually for the xld. Actually have the XLD boards, but prices for the rest of the hardware are holding me back from putting it together.  I was hoping Mr Robot might have an answer for me. It looks like he's running the same combo I want to put together. VBXE, XEL, and gbs8200.  I actually don't really care if the 8200 get's mounted internally or not, so is the GBS-PGM board all that would be required at that point?

[chevymad]

Ok.. had enough time to reread this thread from the start. I'll build up a GBS-PGM board and give her a go. 

[Mr Robot]

What do you need to know?

Here is how to wire up the VBXE https://atari8bit.net/vbxe-1088xel-wiring-diagram/

You don't need a GBS-PGM board to use the GBS8200, it does make the display nicer if you do though. The howto on installing the GBS-PGM is in this thread, after you make it you basically plug it into the GBS board and put a jumper on two pins on the GBS board. I power my GBS from a spare power point on the XEL board. I haven't yet put it all in a a case.

 

Let me go and take a pic of it for you... one sec.

 

[Mr Robot]

OK here is the GBS-PGM plugged into the GBS8220, you can see where the board plugs in, where the jumper goes and where I run power to.

 

Here is where I get power from the XEL

 

 

That and the VBXE wiring diagram should be all you need.

[chevymad]

Thanks for the pics Mr Robot.  I've read in this thread that Csync needs to be connected via a 470ohm resistor. Where is this done? I've got 3 boards made, but my screens are all filling the upper left corner and my monitor gives me an out of sync error message. Pressing the menu button clears the error message, but wont give me access to the monitor settings. Monitor displays garbage in the 50hz settings, even though its multisync. However, if the pgm board switches are put into 50hz while running it will switch and display video. All 3 boards do the same, so unless I made the same error 3x... (actually probable LOL)  Hoping it's all the missing csync line.  My stock gbs looks just dandy with no problems other then the chinese at the start. 

 

Board LED flashes momentary red at start, then continually flashes green afterwards.

[+mytek]

I am very much surprised that you could even get a stable picture without CSYNC being connected. Yes you will need it, and yes a series resistor is required. Anything between 470 to 680 ohms will work, and since the XEL puts out a reduced voltage for its sync, 470 ohms would likely work better. As for where do you make the connection, if you are using the harness that's usually provided, I believe it's  the gray wire for CSYNC input on the GBS and there is a CSYNC out pin on the XEL that you would connect to.

 

[Mr Robot]

My csync isn't connected via a resistor, am I slowly creating a hole in the universe or something else I'm unaware of?