MiSTer 240p 120Hz on a VGA CRT Monitor

Many people in the retro gaming scene are interested in having a “professional monitor” experience, but don’t have the budget for a PVM or BVM.  One alternative to this, is using pretty much any good condition VGA monitor, doubling 240p to 480p (since CRT VGA monitors aren’t compatible with 240p), then adding artificial scanlines.  This results in a really accurate look, at the expense of brightness, which means some older monitors would be too dim to use this method.  One other alternative is to run 240p at 120Hz (instead of 60Hz) – This produces the exact same 240p look, at the expense of lag and motion blur.  At the moment, using the 640×480 method with scanlines is best, but if MiSTer or upcoming devices like the OSSC dexx can add black frame insertion (BFI), it’ll be a close call.  Check out the livestream above for a full demo of this on MiSTer in its current form and there’s a summary below the links:

HDMI to VGA Converters:
More MiSTer Info:
MiSTer Ini Files used in the stream:

MiSTer.ini = Linedoubled 240p – This should be compatible with all VGA CRT monitors.
MiSTer_alt_1.ini = 240p120
MiSTer_alt_2.ini = 240p120 set to scale the video’s height (probably unnecessary)
MiSTer_alt_3.ini = Direct Video (standard 240p output)

First, I’d like to start out with a brightness comparison, to demonstrate why anyone would even care about 240p120 at all.  Please keep in mind that these pictures were captured during a livestream and I wasn’t able to spend the (insane amount of) time I normally do getting these shots right – It’s almost impossible to see the CRT’s mask in these pictures and the overall look IS NOT ACCURATE.  What is accurate though are the brightness differences:


I wanted to run a quick experiment on my 20L5 PVM, to show both the brightness and scanline differences.  Unfortunately, PVM’s don’t like 120Hz at all and the colors didn’t come out right.  When converting the pictures to black and white, I was able to at least show the accuracy of the scanlines, which is another reason people might prefer this over the other method – Slightly more accurate scanlines.







So, as I said before, I don’t think 240p120 is the right choice for most people.  At least for now…if the MiSTer and dexx are able to add BFI – a black frame after every 60Hz frame – there won’t be any motion blur.  Then, the only tradeoff is brightness vs latency. Regardless, if you’re using MiSTer, make sure to select the “HV Integer scale” option in the menu to reduce any shimmering during movement – This is needed for both modes.

I’ll definitely be doing a follow-up stream if those every happen and I’ll spend a lot more time getting accurate comparisons, as well as video demonstrating the motion blur!  For now, this livestream is good enough 🙂

I’d also like to shout out Bahn Yuki for testing this out over a year ago!  The required changes are a bit different now that MiSTer’s evolved a bit more, but groundwork like this is what led us here!:

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