Request: Video Resolution less than 1200p

append delete SvOlli

Let me start off the first serious message here...

Bootstrapping my prototype, I noticed that I've got one serious problem: of all my monitors (>6 different models), only one is capable of displaying 1920x1200 on VGA. If the video output would also support 1920x1080 (aka 1080p) about half of them would work. Going back even lower to 720p (or 1366x768), I could even use my Motorola LapDock ( ) for presentation...

It would even turn the Nexys 4 into a prototype MEGA65 notebook!!!

(Maybe the resolution could be changeable by one or some of the switches on the bottom of the board, so there's no need for any kind of autodetection.)

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append delete #1. gardners


It is quite difficult to support multiple video modes that need a different pixel clock with the design that I have made, because there is no frame buffer -- everything is rasterised in real-time.

That said, I have been thinking for some time that I should see how feasible it is to get 1080p working somehow. Alternatively, it may be easier to make it work in some mode that uses exactly half the current 192MHz pixel clock.

Let me think about it a bit.


append delete #2. Darkreaver

Given that new LCD panels are mainly 1080P, support for that would be nice.

append delete #3. Meshuggah333

1080p should the maximum resolution IMHO. It would keep the spirit of the "retro computer" idea by being compatible with most TV out there, and of course most LCD monitors.

append delete #4. Deft

We looked into the 1080p resolution. Sadly it didn't work out very well for now. As time is very limited and there are more important tasks to complete at the moment, we strongly advise everybody who has problems displaying the 1920x1200 resolution to get a downscaler. While many TVs can downscale the image, others can not. We found and tested a <50 euros solution and it works just fine. The box converts the 1920x1200 vga analog image to 720p and outputs it (plus the sound) to HDMI. This should make anyone happy who has problems displaying the "big one" for now. We will be offering that box to be ordered from us very soon, if you are in a hurry either search on the interwebs or drop me a line...

append delete #5. Meshuggah333

19200x1200 is 16/10 and 720p is 16/9, so you're plan is a little flawed from the get go :) (AR is important)
I have a PC monitor capable of 1920x1200 but I'm a bit disappointed I won't be able to run the thing on my big TV and HC.

append delete #6. Deft

I agree. 16:10 is always better than 16:9 which makes us believe we should stick to what we have. However, the HDMI converter box works fine and the picture looks well. I could not spot serious distortions so this is the way to go for the moment. Next step is we will have our resellers offer that box so you are good to go. Meanwhile you can search and buy one yourself. And again, a 8 year old LG plasma TV for example will do the downscaling by itself.

I will let you know when the box is available. Thank you for your patience.

append delete #7. Ralph Egas

Going with the info in the blog posts and personal experience I can see why changing to 1080p would be problematic as you'd need to change your time scalars on a hardware level.

However, going with a 720p converter solution is really sub optimal, especially on a digital panel of sorts. You're going to lose crispiness of the display. A true 8-bit retro order of resolution wouldn't pose any problems in that area but since the raster at a system level accounts for HD(+) it would be a waste to downscale from 1200p to 720p. Besides that the downscaling and displaying of a 16:10 to a 16:9 will either ruin the aspect ratio or will impose pillar boxing which is equally detrimental.

I'll be using my newly bought Eizo monitor (that is really intended for graphician work stations, lol) for the occasion so I'm not worried for my personal experience, however for Mega65 to become successful in its targeted niche space (forget mainstream ;)) I urge Mega65 to adopt to 1080p at some point before release. This is due to the fact that the whole monitor industry is in the process of shifting to 1080p. Even Apple ditched their 1200 for 1080p or doubles (Retina), which I regret but it's just the way things are.

Folks @ Mega65, is there maybe something the community can do to help going to 1080p or is there any compelling reason beyond "it's really tough to make it work" you could elaborate on?

My 2 cents...

append delete #8. Ralph Egas

Hmm, a quick thought-out solution that just popped up in my mind is of course having a framebuffer after all (or at least partially in a vertical divider sence) that lives *outside* the C65GS space (as far as the C65GS user / programmer is aware) that captures 1080 scan lines, ditches the 120 left towards 1200 and traces those at a different frequency and totally separate from the system.

As far as the user is concerned the beam tracing will have a scan frequency like it is now on par with the 1200p. Looking at the screenshots the horizontal border is very thin which suggests cropping. Losing 120 scanlines due to cropping, 60 on top and 60 at the bottom won't do any harm in that respect, right?

Of course in doing something like this we'll have to sacrifice a part of the 128MB DDR2 RAM. That would amount to 1920 x 1080 x 12 bits/pixel or a mere ~3MB for a *full framebuffer* while maybe only a couple of vertical segments are enough to sync stuff in multiple stages towards filling the whole screen.

I realize I make this sound way too easy but the beauty of above treatment would be at least that there wouldn't be any messing with the current system internally as this solution would be slapped on and could therefore even be upgraded to *post release*.


:: @Ralph Egas added on 16 Aug ’15 · 22:41

P.S. Not only could this solution be slapped on, it could also be made optional (configurable depending on monitor type) more easily!!

append delete #9. Meshuggah333

I'd say yes! Ditch those lines :)
Are those in the border area or can the Mega65 display things on the whole screen? I ask because if there's an actual border and those ditch lines are in it, there's absolutely no loss in doing this.

append delete #10. Deft

Here's your solution! These converters do HD-ready output on HDMI including Audio. They have been successfully tested by us. For 16,99 including shipping they are the perfect solution for now! This does not mean we won't be looking into native 1080p50 in the future, but right now we got other priorities (again: cases, keyboards, pcbs...).

Here you go:


append delete #11. Deft

Update: I bought one of the cheap converters mentioned in last post ( < 18 euros including shipping) and they do full HD! Good value to the money and I guess problem solved for now ;)

append delete #12. Visual Department

That 1200 resolution should be 1080. 1200 is dead and gone.

1080 is more than 80% in the market. Please stick op 1080.

append delete #13. mk

I was owner of LCDs 1920x1080 and satisfied, but since I own 1 LCD 1920x1200 I see that work area is Great, 2nd LCD is 1600x1200 and 3rd Desktop is planned 1920x1200 too and these LCDs are 24" instead 1080 22".
First compare work in 1080 Space with 1200 Space then Mark it as dead.

append delete #14. Deft

I agree regarding "more is better" but I understand that you want to use the MEGA65 in combination with your TV set. We are have not given up on native 1080p50 and it probably will work at some point. Worst case would be to equip the MEGA65 computers with a built-in downscaler and HDMI socket. All will be good ;)


append delete #15. LoveMega65

Will Mega65 support composite,s-video and RF output?

append delete #16. Deft

There will be an analog output, probably composite or oldschool RGB. Goal is to be able to connect a 1084s or other oldschool comodore monitor.

append delete #17. Ordyne

RGB would be good as it could also be used with scart, I suppose S video is also possible.

append delete #18. MIRKOSOFT

So, my earlier post in this thread was about 1920x1200...
Now I have PC with 3 desktops - two 1920x1200 and one 1600x1200 (later exchange to 1920x1200).
Reasons of this 16:10 1920:1200 was not M65, I had 2x 1920x1080 and when I was working with 1600x1200 I saw difference of 1080 and 1200...
In case of M65 is also required 1920x1200 16:10 instead 1080. Why? Simple resolution of VIC-II(e) is 320x200 - and it has also 16:10 aspect ratio.
I own also PEXHDCAP capture device and it allows capture up to 1080 Full HD - what I did for capture? Bought downscaler with variable resolution scaling and used 1680x1050 to use. So, for retro feel can have also other outputs, but will be limited by resolution. I hope that 1920x1200 will be always available.


append delete #19. gardners


Regarding the comments about aspect ratio being messed up with down-scalers, we can actually correct for that in the VIC-IV, since everything actually passes through the horizontal hardware scaler, anyway. Thus if you picture is too fat or too skinny, or just in the wrong horizontal position, you can fix it. You can see me do this when the MEGA65 gets its first outing on a 200 inch screen:

Naturally, we will one day make kickstart allow you to define persistent settings for this sort of thing.


append delete #20. Ratteler

Is there enough room in the FPGA to add a scaler?
I mean, if there is a >$20 device for sale, it's probably not SO complex that it couldn't be implemented in FPGA.

Less adapters are always better.

:: @Ratteler added on 02 Apr ’16 · 09:11

Also, what about future proofing in 4K UHD?

append delete #21. gardners

We are thinking about how to make the output resolution / frequency more flexible, however yet to make any firm decisions. The first step is to reduce the size of the core, as we are getting a bit close to filling the FPGA already, then we can see what we have space for.


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