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Vertical Refresh Rate: set by game software or monitor hardware?
torino:
--- Quote from: Calamity on March 28, 2011, 11:50:34 am ---
--- Quote from: torino on March 28, 2011, 09:52:27 am ---where did those numbers come from?
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Some may be guessed, some actually measured, I don't know how they're actually doing it, but I trust this information as the best one available, and in fact these values change sometimes as Mame is updated, probably due to more exact measurements being done.
--- Quote from: torino on March 28, 2011, 09:52:27 am ---We can plug in many different numbers in there and get all kinds of numbers as a result...
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Well not so many indeed, horizontal values are actually 'characters' not pixels, so they are always multiples of 8. Master clock frequency is usually a known value. Total number of lines (vtotal) is actually measurable with an oscilloscope. Vertical refresh too. So you don't have so many possible combinations of htotal, vtotal, dotclock that can produce a measured vfreq.
--- Quote from: torino on March 28, 2011, 09:52:27 am ---Why do you think CPU would work in multiples of refresh rate?
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No, I didn't say that. Refresh rate here is the final result. It's the dotclock the one that is probably an integer product of the master clock, applying a logic of simplicity, these machines probably had a master oscilator and the rest of frequencies may have been obtained by multiplying or dividing that master frequency by an integer value.
--- Quote from: torino on March 28, 2011, 09:52:27 am ---Could it be their measurement was influenced by the regularity of video interrupt so it only _appeared to their instruments as if CPU works like that while it actually does not? Would you really be surprised if I tell you my Galaga PCB just so happens to work with my totally fixed 60Hz LCD monitor and OSD says it's being run at exactly 60.00Hz?
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Unfortunately I'm not a native English speaker so can't deal with irony here in the way I'm used to when using my language. Anyway, I have the feeling your style sounds familiar to me.
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I believe my question is very reasonable and if you think it's not then please explain why do you think so. I also agree with what you said and I find all that reasonable too, but different people have different priorities, and curiosities, so I must ask:- what if Galaga is meant to be running at 60Hz round, what if those numbers behind decimal point are actually just result of some imperfections of that particular measurement and that specific board, maybe due to age or heat. It would be really silly that we now can not properly sync this game with our fixed 60Hz LCDs just because some measurement error, wouldn't it? And do you agree even PC CRTs have (had) enough flexibility so they could run at vertical 60.606061Hz while LCDs can not as they have truly fixed refresh rate?
torino:
--- Quote from: MonMotha on March 28, 2011, 03:25:54 pm ---If you honestly want this troubleshooted, you will need to define "sync up". I'm suspecting a simple driver issue which may or may not be easily resolved.
I'd also suggest being less aggressive. You're coming off as a bit trollish. In fact, you remind me of a friendly forum troll we know as driver-man. If that's not who you are, trust me when I say you don't want to be mistaken for this person.
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I'm sorry, you lost me there. What "sync up", what driver are you talking about? Is there any way to use some fancy multimeter or maybe a computer to measure this stuff? Joystick port is analog and can take variable voltage in 5V range, so there must be some software that can turn a PC into oscilloscope, one way or another, right? Google here I come...
Have you realized by now LCDs can not update screen at variable range of refresh rates? Even in the case where they can take some range as input they would end up refreshing their screen at internal rate which usually is 60Hz, or perhaps 120Hz, but if they say it's 75Hz or 85Hz better watch out as your picture (motion) will be ruined since they would most likely just downgrade it to 60Hz and so you will end up with worse animation than if you were feeding 60Hz to start with.
Otherwise you seem to be well aware of this technology involved in processing, converting and displaying video streams of different formats, and I thank you for taking an interest and time to make this little chat, so the only other thing I can think of to complement your knowledge would be to point out to how it all started and where it all begun. If you already don't know I think you should find it interesting: http://en.wikipedia.org/wiki/Telecine
SavannahLion:
--- Quote from: MonMotha on March 28, 2011, 03:25:54 pm ---I'd also suggest being less aggressive. You're coming off as a bit trollish. In fact, you remind me of a friendly forum troll we know as driver-man. If that's not who you are, trust me when I say you don't want to be mistaken for this person.
--- End quote ---
I concur. I reached that conclusion pretty early.
SavannahLion:
--- Quote from: MonMotha on March 28, 2011, 08:06:30 am ---What your monitor will do when presented with something outside this range depends on what the designer told it to do: some will attempt to convert while others will give an "out of range" error.
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Remember when there was no such safety mechanism? You had to be careful not to set the range too far out of whack. ;D
Hoopz:
Reminds me more of Genesim than Driverman. YMMV.
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