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Post by mrbombermillzy on Jul 23, 2016 20:41:46 GMT
You can forget anything about the PAL/NTSC VICIIe video system for the RGBI output. Its more like (well pretty much exactly, apart from the brown/dark yellow) the IBM CGA digital out from the 9 pin din DB-9 connector.
However, do have a go and experiment with the machine. Especially the 8563 VDC! :-)
I would HIGHLY recommend that you dont desolder the VDC ram, as its much easier to just plug in an upgrade kit without having to solder anything.
There are a few people round here who are starting to really get the ball rolling with some new and very interesting projects for the 128. I have left detailed instructions in another thread on how to increase the native resolution to a possible 1024x592i resolution if you have the right monitor. There are also other video tricks by others which can display VGA output (once converted to RGB analog) and VICIIe interlace modes.
There are also new cartidge projects and various bits and bobs being done. An interesting time to own a C128, i think. :-)
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Post by mrbombermillzy on Jun 27, 2016 16:38:21 GMT
Woohoo!
The original C128 fountain of knowledge is back!
Um, but maybe with a little bit of the knowledge missing, it seems.
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Post by mrbombermillzy on Jun 22, 2016 17:34:04 GMT
In regards to the talk of Genlocking the VDC, I found this quote, "RES - Reset input to initialize all internal scan counter circuits. The control registers are not affected. RES can be used to synchronize the display frame to an externally generated signal. This signal should not be confused with the INIT input." So yeah, Syncing then overlaying the VDC should be possible using that pin. In theory. Well that's definitely going to come in handy for genlocking, I'm sure and it could be useful for other tricks... I will have to experiment with it at some point. I know Ive been spitting out all these different ideas, but its mainly because I am here twiddling my thumbs, so to speak, as I am still waiting for my electronic parts. Also my workstation is behind lots of other clutter. I will get it sorted out as soon as all the required components are here. I did get a bag of crystals turn up yesterday (no I don't mean that type of crystals!) so nearly there now. However, it is good to have a plan and a good discussion about the options! :-) I'm happy that there are a few people here who look like they are willing to go forwards with some sort of graphical improvement for the 128. I think that will, in turn, spur more software development for the machine, if we do it right. And at least one of you is keen to see how my experimenting turns out, so I will (soon) get back to work!
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Post by mrbombermillzy on Jun 21, 2016 18:26:20 GMT
Well done Pyrofer. Sounds like you snapped up a bargain there! :-)
OK, well seeing as we are on the subject of TFT monitors, there was another avenue that I wasn't particularly keen to explore on a CRT, but it might work on a flat screen.
I was thinking along the lines of attempting to force a higher refresh rate than the standard 50/60HZ. Probably need some input from someone with more experience on this one as I haven't even looked into how to do this yet.
Do you get much flicker from colour switching (worst case scenario) white to black at, say, 25Hz on a flatscreen?
This could alleviate the lack of colour problems for Steve's colour circuit.
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Post by mrbombermillzy on Jun 20, 2016 20:03:58 GMT
@ Robert B; regarding monitors:
If they could multi scan between 16-30khz then that would be great. Most monitors these days are set at the standard PC resolution settings, and won't budge below 31khz. You can get the hyper expensive TFT EGA monitors but even then I believe they are rated at 640x200/400 ish res.
As for the Amiga compatibility: The point I was trying to make is that even if there was one game that was not compatible with an A500 KS1.2 512mb or a A1200 with KS3.1 that would be more than for the C64. You have to factor in processor for some games, memory for others, kick start version for others, etc. Nowadays though, the C64 scene has started to tinker around with 16mb REU demos and the like, so its a bit more fractured, but generally any C64 demo will work on ANY C64 (well, 99% now! Lol). The only thing really needed is a 1541.
@steve:
Whatever you come up with will already be better than the C128 CGA inspired pallette! Lol!
So, are we talking an 8 bit pallette with 16 colours available at any one time? I'm guessing then that the pallette choice would all depend on the actual picture being displayed, which is a tough problem to crack.
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Post by mrbombermillzy on Jun 19, 2016 13:08:26 GMT
If we could get RFO demo working correctly on a FPGA reimplementation of the VDC then I would be fairly happy with that. However my end goal is really to reliably (as in not being a substantial risk for any VDC owners) crank the clock speed up to get the maximum number of NON CORRUPTING characters on screen so that I can reduce the character h.size as much as possible to give a higher density colour cell ratio.. eg:
1600 h. Pixels / 4 pixel char size = 400 horizontal pixel resolution with completely independent colour pallette choice. NB: Initial tests have only allowed me to drop the h.char size to 7 pixels so there is still a possibility that I can't get it this low!
Equally important would be the 1280 to 1600 h.Res 'productivity' mode, which would have the same attributes as the standard VDC settings.
If you think you can get a reliable VDC core running then we could possibly have some o/c options on that too. Perhaps have it running at 32+mhz? :-) This would allow a higher resolution unlimited (as in any of the 16 colours) pallette density. And this is still without SJRay's colour modifications!
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Post by mrbombermillzy on Jun 19, 2016 12:34:04 GMT
Well, that's fine if it will work acceptably and we are going to use 'standard' 80x25 modes. Personally, I'm just wanting to see what I can do with a sped up and non memory restricted VDC. Perhaps some 'bolt on' compatible colour system too, hence Steve's project.
With a FPGA implementation, there will be another 'fork' of the C128 system for the future coders/system hackers to have to learn for program compatibility, (Hence my earlier stab at the Amiga and its many incompatible incarnations) as it will be close enough, but not the same as the real h/w. So there will have to be s/w versions for users with the 'real' h/w and users for the FPGA version.
Looking at my figures, so that I can give you a rough idea of what I should be able to do:
If I can hit between 20-24khz from the 8568 VDC reliably, which seems quite reasonable, I can get the VDC chip to interface to a VGA monitor at around 640 to 800 h.pixels. This should be with non corrupt characters on the screen and a little rgbi to rgba circuit.
Now, this 'upgrade' should just require a piggyback board, just like the 16 to 64kb VDC upgrade kits which are available for the C128 and earlier 128D models. It can also be switched on/off if required too. Now I would imagine most users would be pretty confident in doing the mod and it won't cost much either.
On top of this, the VDC will have the same nuances as it always did (perhaps now without corruption), and won't need any different techniques or workarounds. We could even burn a modified kernal ROM to set the tweaked registers for the upgrade kit. Now with the colour upgrade I believe that this path would be the cleanest way to go.
FWIW, if you are willing to lose the VGA frequency standard and still have an old school PC/Amiga multisync lying around, we should be able to hit 1280 or up to 1600 h.pixel modes.
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Post by mrbombermillzy on Jun 19, 2016 6:57:29 GMT
Yes, we were discussing in another thread the Scanntronik Genlock. This one would have to be a stripped down/simplified version to be cost effective and small enough though.
As for VDC emulation, there are several problems in the VICE x128 VDC emu and this seems like the most well developed one. Maybe see what Groepaz has to say as he seems to be dealing with that side of things. I think someone will eventually de-lid a VDC chip like they did on the SID to get to the bottom of it. However, as you imply, they are too precious and few and far between nowadays.
I'm pretty sure with a sped up dotclk and a reduction in h.frame size to increase frequency, you would lose a bit of that extra resolution, but we can hit 31khz at a fairly respectable resolution. Its then fairly trivial to convert the digital signal to rgb analogue. This would probably be a far easier job than FPGAing the VDC with a very high accuracy.
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Post by mrbombermillzy on Jun 18, 2016 17:05:43 GMT
That's a good way to do it. However, might this reset perhaps affect any VDC memory fetches or anything like that? My solution would have been to phase lock the (double speed) VDC clock with the VIC one. Again, maybe having to tweak the VDC registers slightly so that the VDC can run at exactly 2x VIC CLK. There is also a CHRCLK output which looked as if it could come in handy timing wise.
I did consider re attaching the vertical interrupt line too. This would be SO useful. But where?...
I would also suggest to superimpose the VIC OVER the VDC which would be much more practical.
And yes the PRG is good for a basic foundation, but ultimately, you have to find out the gritty details yourself. I've found a lot of useful third party technical information but its for the '63 so not ultimately 100% accurate for the later '68.
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Post by mrbombermillzy on Jun 18, 2016 12:38:09 GMT
Lol! Its one of the solutions I have explored too, along with one of the circuits on your ColourPET page was using a Ramdac system to generate the colours so I kind of guessed you might be heading in that direction!
I did also consider a VICIIe/VDC genlock but...one thing at a time and all that.
However, I really believe whatever route is taken here, it should be 'downwardly compatible with the regular vdc. I'm sorry if I keep repeating the 'maximum common benefit for the community' mantra, but I believe its what made the C64 scene a solid and arguably less fragmented one than the Amiga one (Which kick start ROM/RAM size/680xx processor do I need for this demo/game??!).
Although saying that, there's not really much VDC specific software to keep compatible with, so maybe just go for it.
Both of those solutions seem worthy of exploration, although I would probably go for the first one, as it is simpler and perhaps easier for the average C128 owner to make/afford?
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