Using MiST to drive an Arcade Vector Monitor

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phoboz
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Using MiST to drive an Arcade Vector Monitor

Postby phoboz » Mon May 13, 2019 8:29 am

I have recently built an arcade vector monitor out of an old TV set.
https://www.youtube.com/watch?v=kdUSU4RqZe0

Currently there are 2 options for generating an analog vector signal for it, either by having a real Vector Arcade PCB which are hard to find in working condition there days, or to use the ZVG Zektor vector generator with MAME. Unfortunately the ZVG is old and required a DOS PC with parallel port, and the ZVG is also both hard to find, and very expensive.

Therefore I was wondering if I could use the MiST somehow as a Vector Generator. It would need to be able to output 2 analog signals. Is that possible using the stereo headphone jack? The input commands could be sent on the USB port instead of a parallel port as on the ZVG.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby slingshot » Mon May 13, 2019 8:54 am

I have no idea what input is required, but the VGA output also analogue, and you only have to create a (3x)6-bit digital representation of the required signal. Possibly some kind of level-shift also needed.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby phoboz » Mon May 13, 2019 11:04 am

slingshot wrote:I have no idea what input is required, but the VGA output also analogue, and you only have to create a (3x)6-bit digital representation of the required signal. Possibly some kind of level-shift also needed.


Yes the RGB I can take from the VGA connector. However, for a vector display to work, I need additionally 2 analog signals that moves the x, and y position of the electron beam. The VGA sync signals pins cannot be used, as they are either high or low)
The x, y signals needs to be able to assume all the values between the following voltage ranges:
* X-voltage: +/- 8v
* Y-voltage: +/- 6v

E.g. the vector display draws vectors by feeding the x, y signals to the deflection yoke. The vector is drawn by holding the RGB colors at the desired color value while moving the electron beam from the vector's starting point, to it's end point. So in total i need 5 analog signals R, G, B, deflectionX, and deflectionY. That's why I am asking from where I could get these 2 additional analog signals.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby RealLarry » Mon May 13, 2019 11:25 am

I can't help, whether in technical nor programming, but this article https://www.jmargolin.com/vgens/vgens.htm maybe helpful in any way.
On the other side of the screen, it all looks so easy.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby slingshot » Mon May 13, 2019 2:20 pm

phoboz wrote:Yes the RGB I can take from the VGA connector. However, for a vector display to work, I need additionally 2 analog signals that moves the x, and y position of the electron beam. The VGA sync signals pins cannot be used, as they are either high or low)
The x, y signals needs to be able to assume all the values between the following voltage ranges:
* X-voltage: +/- 8v
* Y-voltage: +/- 6v

Then you don't have much choice. I think you should drive the AUDIO_L and AUDIO_R pins through a PWM DAC in the FPGA, and you'll need some kind of amplifier, too, connected to the stereo output.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby Televicious » Tue May 14, 2019 5:37 pm

You could probably implement a vector VGA scan converter in the FPGA, but you'd have to get a hold of one to map it out and they are expensive not to mention rarely available. They probably use some closed source FPGA actually. Contact them, may be open to assisting a project. https://vectorvga.com

Then there's that laser projector vector project where the guy rebuilt asteroids to display through lasers. Pretty sure all his stuff is in software though.

There is the multivector board.
https://www.ebay.com/i/223465496842?chn=ps

I guess those are all making use of nonvector displays though because it also depends what monitor it actually is. Some vector monitors are made for specific game boards in mind like Tempest has some of the image controls built into the actual game PCB. Star Wars also has a different specific model.
At best depending on your monitor you could get a handful of vector game boards mapped for it.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby phoboz » Wed May 15, 2019 11:26 am

Televicious wrote:I guess those are all making use of nonvector displays though

What I want to do is the opposite. Because I have built one of these rare vector monitors (this one is actually a clone of the Amplifone display that was used in Atari games like Tempest, Star Wars, Major Havoc etc.).
Now I want to feed it with a real vector signal, like the signal a real Tempest arcade board would produce. So this is what I want to generate.

I guess that a stereo PWM signal could be used to drive the X/Y deflection coils on the yoke. Question is if the voltages can change rapidly enough? I guess that depends on the duty cycle of the PWM signal.

PS. The whole thing with having a real vector monitor is that you get ultra-smooth lines, without the stepping effect you get on every raster display (even in UltraHD, 4K etc. you can see the jagginess if you get close enough) You also get a very clear distinction between the lit areas and the black areas, which in my opinion you cannot get with a raster display. The downside is that you seldom see completely filled areas in a vector game, because that would be extremely expensive in terms or drawing time. Think of this as the difference between a printer, and a pen-plotter (if you remember these)

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Re: Using MiST to drive an Arcade Vector Monitor

Postby Televicious » Wed May 15, 2019 5:20 pm

Well it looks like you should be able to output X/Y over the VGA.
https://www.youtube.com/watch?time_cont ... fBwz_SiK8s

Tempest uses a Wells-Gardner 6100. Not all vector game boards are designed for all vector monitors, but could probably be adapted. I've never seen it though.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby phoboz » Thu May 16, 2019 1:43 pm

Televicious wrote:Well it looks like you should be able to output X/Y over the VGA.

Yes, for a monochrome Arcade game like Asteroids, Battle Zone etc. Because if you only need on channel for intensity, and you can use the other 2 color channels on the VGA connector for X/Y. However, for a color vector game, like Tempest, Star Wars, Major Havoc etc. You would need 2 additional channels for color (all 3 of Red, Green, Blue is needed). Also the VGA gives TTL level output (0-5 Volts), however, the Amplifone, WG 6100 expect +/- 8V e.g. in total 16 Volts for the X-deflection, so some kind of amplifier would be needed.

As I understand it the WG6100, and Amplifone (both color displays used by Atari) are electrically compatible. However, they might not be mechanically compatible. E.g. both take +/- 8V on the X-deflection, and +/- 6V on Y-deflection, both has a built in spot killer etc. However, the Electrohome G08 (used by SEGA) would not be directly compatible with the Atari color monitors.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby Televicious » Thu May 16, 2019 7:52 pm

I'd love to see black and white vector gaming and keep the audio. Audio is just way too important to sacrifice for color. Maybe some super high quality DAC's from the H-sync/V-sync to the X/Y amplifier could do the trick though.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby phoboz » Fri May 17, 2019 8:06 am

Televicious wrote:I'd love to see black and white vector gaming and keep the audio.

There is already a Vectrex core for MiST, that outputs to a regular raster display.
http://www.atari-forum.com/viewtopic.php?f=115&t=33150
However, this might be adapted to output Real Vector Graphics to a Vector Monitor. If connecting to one of the color channels to a color vector display, you would get everything in red, green, or blue. Or a connection could be to a B&W Vector Monitor, like the Electrohome G05 for black and white Vector Display.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby slingshot » Fri May 17, 2019 1:17 pm

phoboz wrote:However, this might be adapted to output Real Vector Graphics to a Vector Monitor. If connecting to one of the color channels to a color vector display, you would get everything in red, green, or blue. Or a connection could be to a B&W Vector Monitor, like the Electrohome G05 for black and white Vector Display.


Sounds like a great project.

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Re: Using MiST to drive an Arcade Vector Monitor

Postby Televicious » Fri May 17, 2019 5:03 pm

phoboz wrote:
Televicious wrote:I'd love to see black and white vector gaming and keep the audio.

There is already a Vectrex core for MiST, that outputs to a regular raster display.
http://www.atari-forum.com/viewtopic.php?f=115&t=33150
However, this might be adapted to output Real Vector Graphics to a Vector Monitor. If connecting to one of the color channels to a color vector display, you would get everything in red, green, or blue. Or a connection could be to a B&W Vector Monitor, like the Electrohome G05 for black and white Vector Display.


I was looking for that, link was broken on the page, here's the actual core. Should definitely put that on the MiST wiki.
https://github.com/Gehstock/Mist_FPGA/b ... x_MiST.rbf


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