Amiga.org
Amiga computer related discussion => General chat about Amiga topics => Topic started by: IOWASURFER on October 29, 2007, 07:09:55 PM
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Been chatting with a gent about making the Amiga community
a scan doubler...
This device would hook to the rgb port and allow a sync to 31hkz to any vga monitor but wanted to know who would be game..
These have been working on Atari computers rock solid for awhile now and
i believe they would work just fine for Amiga as well...
Would be about $65-75$ but wanted to see if there was any interest first???
http://www.miba51.com/CoCo_VGA_Adpater.html
If theres enough interest Roy said he would make and sell them to Amiga folks..
Here is a flicker fixer/ scan doubler going on ebay now
I was bidding at 222$ I got out bid and I said heck with this has to be a better way
and then I found Roy!
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As soon as he has a prototype will post the results here!
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Joe..
_________________
Friends Do not let friends use IBM's.......
(2) TWIN Amiga 1200A 6804 1240
(1) Amiga 2000 GE-Force 6804 WB3.9
(6) Amiga 500
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Hi,
Well I'm interested, but I'd like to see the results on an Amiga 1st
cheers, Justin
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I would say for that price about half the Amiga.org users would buy one.
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Yeah I might like to buy one too considering I hate to have too many monitors on the desk so I could just use a switch instead for my LCD :)
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Not sure I get it... the XRGB2 is pretty expensive, and difficult to find now.
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I'd buy 3 for that price, but I would also want to see this tested with an amiga in PAL\NTSC modes and with FlatScreen LCD in PAL\NTSC screen modes... If it works with an Amiga well in these modes, then I'd definately buy...
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This chap has made a scan doubler for the Atari and now I asked him to look into the Amiga so he is concentrating on the Amiga now he has been able to make them for 65-75 $ USD recently as last year.. IF he can do the same for the Amiga we will have a very cool solution...
Joe..
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If it was all ready to go for an amiga I'd get one for $75 and two if they were $65.
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I guess what I'm not understanding is that the link is for a device that connects a coco to an XRGB... the Amiga can connect to an XRGB with nothing more than a SCART cable. (In fact, doesn't the XRGB handle 15kHz via an RGB in?)
Granted, if someone can produce a scan doubler + flicker-fixer for $65, I'm sure it would sell very well.
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I would definately have one for that price.
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http://www.miba51.com/CoCo_VGA_Adpater.html
here is the one Roy worked on for the Atari..
I believe its his design or a variation..
The info is on this site..
Joe
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Yes and the key is to test it with Amiga Games as well...
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Hmmm i am just happy i just found a scandoubler for my a1200 elsewere "internal one " :-p but have to say not for this price
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http://www.miba51.com/CoCo_VGA_Adpater.html
Here are the details!!
I talked to Roy the one making the boards for ATARI right now.. He is currently working on this for the Amiga and would like to take some time and see how it comes out!!!
Joe..
alexh Posted on: 2007/9/28 8:28
Defender of the Faith
Joined: 2005/4/30
Posts: 1012
Oxford UK
alexh has talked about this for awhile..
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Re: Amiga RGB to VGA monitor - recent experiences?
If you dont mind a 16-bit scandoubler / flicker fixer then you can buy them in the US for $48
http://www.miba51.com/CoCo_VGA_Adpater.html
http://www.atari-forum.com/viewtopic.php?t=10709&start=0
Email Roy R. Justus (RJRTTY at aol dot com) for details.
While fine for ECS, there is a slight loss of colour resolution in AGA.
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IOWASURFER wrote:
http://www.miba51.com/CoCo_VGA_Adpater.html
here is the one Roy worked on for the Atari..
Actually that website shows Roy's first(?) use for his scandoubler, the Tandy Colour Computer (aka CoCo).
I believe its his design or a variation..
The info is on this site..
Yes I think it is, based perhaps on the Averlogic reference design. So far his scandoubler looks to be approx the same design between different computers (Tandy, Atari) perhaps a little evolution between revisions.
AFAIK he tweaks the default register settings to find the best one for each computer. centering, contrast, brightness, overscan etc.
The source code for the "tweaking program" and the I2C emulator is/was available from the Averlogic support site.
I guess you'd have to ask Roy about a cable if you wanted to tweak the settings yourself.
The heart of the scandoubler is/was an Averlogic AL875 ADC and an 16-bit AL250A Scandoubler/Flicker Fixer.
The big downer is that it is 16-bit, which means a fewer colours for AGA screens (which can be 24-bit). The Atari STe and ECS Amiga are 12-bit which are fine.
The little downer is that it probably wont work (well) with every Amiga screen mode possible. But I am sure it will work with PAL/NTSC with and without lace fine.
I hope that this time he uses a sheilded monitor cable instead of a ribbon cable like on the Tandy and Atari.
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The magic question though is does it work for the Amiga Video Toaster?
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Not by default.
A quick browse of the internet seems to show the video toaster to have 720 x 480i 60Hz Y/C outputs.
This is an RGB scandoubler by default, but it can be tweaked in software to be a Y/C scandoubler.
You would need to ask Roy about the tweak program and cable.
If anything this would work BETTER with the video toaster than an AGA Amiga because 16-bit Y/C can display more colours than 16-bit RGB.
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-D- wrote:
I guess what I'm not understanding is that the link is for a device that connects a coco to an XRGB...
No it aint, it's a CoCo 15KHz RGB to 31khz VGA. I think the URL kinda gives it away ;-)
Granted, if someone can produce a scan doubler + flicker-fixer for $65, I'm sure it would sell very well.
The Averlogic chips are dirt cheap as they are in most low cost LCDTV's.
Roy is making a profit at $65-$75, and so he should, anything less than 50% profit he wont bother making more than a handful.
That said, I dont know how he first sold them (albeit at cost) for $48 including PSU? I guess that was before the decline of the US dollar.
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If I get a scandoubler, I want one that will do 24-bit RGB color rather than 16-bit. I don't mind if it's internal though.
I'll probably wait until Hi-Def TVs come down in price and use one of those.
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If you intend to use it on an A1000, A500, A600, A2000, A3000 or CDTV (that must be well over 50% of all Amiga's ever made?) then a 16-bit scandoubler wont make an ounce of difference as they are all 12-bit.
Some HDTV's have 16-bit RGB scandoublers.
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I would be interested in one for my A2000 native video out.
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If I didn't own 7 or 8 1080/1084 monitors already I might be more interested in this thread, but just out of curiosity, did the guy make any Amiga SD/FFs and has anyone from here tested one?
Did they sell for $48, or was the price higher?
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The 65-75 was just my best guess could be a lot cheaper or vice versa until he is done with the first AMIGA prototype however with his ATARI successes I bet he will come up with some good stuff..
I guess the best thing about this scan doubler is it allows the little man to have a easily found cheap solution for a real Amiga computer without paying a leg and arm..
Finally a real hardware solution for the AMIGA if he can get them tweaked ALEXH we will be in for a treat dont ya think!?!?!
Joe..
:)
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alexh wrote:
-D- wrote:
I guess what I'm not understanding is that the link is for a device that connects a coco to an XRGB...
No it aint, it's a CoCo 15KHz RGB to 31khz VGA. I think the URL kinda gives it away ;-)
The link in the op has now been corrected... it was originally something about a coco -> XRBG2 adapter. :-P
EDIT -- Also, I think it's fair to point out that this unit would be fine for the majority of AGA games/demos (256 color screens). HAM modes aren't used often (at all?) for games at least.
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-D- wrote:
EDIT -- Also, I think it's fair to point out that this unit would be fine for the majority of AGA games/demos (256 color screens). HAM modes aren't used often (at all?) for games at least.
The palette entries on an AGA system are 24-bits long. The colors would look a little off on AGA. I've got an A1200 and I want AGA colors to look right. I intend to play Total Chaos with this and it has splash screens in HAM8 also.
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SamuraiCrow wrote:
-D- wrote:
EDIT -- Also, I think it's fair to point out that this unit would be fine for the majority of AGA games/demos (256 color screens). HAM modes aren't used often (at all?) for games at least.
The palette entries on an AGA system are 24-bits long. The colors would look a little off on AGA. I've got an A1200 and I want AGA colors to look right. I intend to play Total Chaos with this and it has splash screens in HAM8 also.
Bullspit.
Millions of devices around the world use these chips for video playback, I guarantee it will handle 256 simultaneous colors just fine, with or without an internal 24-bit palette. It will be at least as capable as any earlier "amiga specific" scandoubler.
Furthermore, if it is indeed using the Averlogic chips which alexh mentioned, they both have 8-bit DACs each for RGB. Also, the AL250 has an additional LUT for gamma correction, essentially (I assume) so that manufactures can tweak the output for best results with their application. (Pretty decent feature, actually, something Eizo advertises as well.) Look up the datasheets yourself, it's right there in black and white.
In addition to this, a good majority of consumer LCDs out there aren't "true" 8bpp panels anyhow (even some which are advertised to be). I also appreciate a good display, but let's not get too ridiculous about the color output of an early 90s era computer. (HAM8 mode is essentially a 15-bit *external* output, anyhow.)
Bottom line, if you want something better be prepared to shell out multiple thousands... and then ask yourself, "is it really worth it?"
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-D- wrote:
EDIT -- Also, I think it's fair to point out that this unit would be fine for the majority of AGA games/demos (256 color screens). HAM modes aren't used often (at all?) for games at least.
-D- I am sorry man but that is not true! We've had this conversation before. AGA modes (including 256 colour) are 24-bit! For example a 256 colour screen has 256 different, 24-bit colours!
Using a 16-bit scandoubler for AGA demo's and games will give bad results almost all the time.
How bad depends on the colours in the program.
As an example, open this image in windows with a 24-bit (or 32-bit) screen.
http://www.spronkey.com/sdc-gradients.png
Then change the colours to 16-bit. You will see the loss of information on the 256-colour (smooth) gradient bars, but also on the others.
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alexh wrote:
-D- wrote:
EDIT -- Also, I think it's fair to point out that this unit would be fine for the majority of AGA games/demos (256 color screens). HAM modes aren't used often (at all?) for games at least.
-D- I am sorry man but that is not true! We've had this conversation before. AGA modes (including 256 colour) are 24-bit! For example a 256 colour screen has 256 different, 24-bit colours!
Using a 16-bit scandoubler for AGA demo's and games will give bad results almost all the time.
How bad depends on the colours in the program. If they were 256 shades of red for example (highly unlikely) you would only see 32 of them.
As an example, open this image in windows with a 24-bit (or 32-bit) screen.
http://www.spronkey.com/sdc-gradients.png
Then change the colours to 16-bit. You will see the loss of information on the 256-colour (smooth) gradient bars, but also on the others.
Alexh I'm not necessarily disagreeing with that, all I'm saying is that I'm not convinced this unit is 16-bit and/or would b0rk the color output.
And I agree, 24-bit color gradients will look messed up switched to 16-bit. But this isn't exactly the same thing, as AGA isn't capable of *outputting* smooth gradients, since it can't simultaneously display the amount of colors necessary for that (and HAM8 produces nasty color artifacts).
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I don't want to throw water in the kettle, but the only limitation to this SD is it not SD the "special" screen modes an Amiga can do (DBLNTSC, DBLPAL, Euro modes, etc).
But for 15kHz modes it works just fine, I think.
For retro machines it works fine (A500, 600, etc). Specially for games.
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-D- wrote:
Alexh I'm not necessarily disagreeing with that, all I'm saying is that I'm not convinced this unit is 16-bit and/or would b0rk the color output.
And I agree, 24-bit color gradients will look messed up switched to 16-bit. But this isn't exactly the same thing, as AGA isn't capable of *outputting* smooth gradients, since it can't simultaneously display the amount of colors necessary for that (and HAM8 produces nasty color artifacts).
Sorry but you are just thick if you cannot understand it.
The 16-bit scandoubler ignores the 3 LSB's of Red and Blue and 2 LSB's of green. That means that an AGA colour with a blue value of 0 is displayed the same as an AGA colour with a blue value of 7! (assuming the other components are the same)
AGA can display smooth gradients. If say the colours in a program used 256 shades of red for example (highly unlikely but possible) it would have ALL the possible RED shades of a 24-bit screen and if you use a 16-bit scandoubler you would only be able to distinguish 32 of them from the others.
You get a BANDING effect as what was supposed to be a subtle gradient of colours appears as one.
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-D- wrote:
Millions of devices around the world use these chips for video playback
Ah, yes but they DONT use the RGB input they use the Y/C input which doesnt need 24-bits for a reasonable colour reproduction
-D- wrote:
It will be at least as capable as any earlier "amiga specific" scandoubler.
Bollox, the Arxon (http://amigahardware.mariomisic.de/cgi-bin/showhardware_en.cgi?HARDID=357) and petsoff (http://amigahardware.mariomisic.de/cgi-bin/showhardware_en.cgi?HARDID=375) scandoublers are both 24-bit RGB scandoublers.
-D- wrote:
Furthermore, if it is indeed using the Averlogic chips which alexh mentioned, they both have 8-bit DACs each for RGB.
Absolutely true. But the AL250a only has 5/6-bit inputs! You cant magically get data back once you've thrown it away!
-D- wrote:
HAM8 mode is essentially a 15-bit *external* output, anyhow.
You've read too much crap off the internet.
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Sorry but you are just thick if you cannot understand it.
The 16-bit scandoubler ignores the 3 LSB's of Red and Blue and 2 LSB's of green. That means that an AGA colour with a blue value of 0 is displayed the same as an AGA colour with a blue value of 7! (assuming the other components are the same)
LOL, I'm "thick" because because the datasheets for the chips you mentioned state they have 8-bit DACs for each color, yet you keep saying it's 16-bit. That's pretty funny.
This has nothing to do with me not understanding the difference between 16 and 24-bit output. Any dumbass can switch from truecolor to highcolor and see the difference (and I've already stated my awareness of the AGA 24-bit *internal* palette).
AGA can display smooth gradients. If say the colours in a program used 256 shades of red for example (highly unlikely but possible) it would have ALL the possible RED shades of a 24-bit screen and if you use a 16-bit scandoubler you would only be able to distinguish 32 of them from the others.
Yes, using 256 colors it's possible for a smooth gradient, but as you've stated, highly impractical. Try viewing the image you linked to on an AGA screen, and it will look like ass.
You get a BANDING effect as what was supposed to be a subtle gradient of colours appears as one.
Due to the very nature of how HAM works, you get fugly looking images, gradients included. This even has nothing to do with HAM8 not being a 24-bit output in the sense of displayable colors, regardless of the internal palette.
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quote]
-D- wrote:
LOL, I'm "thick" because because the datasheets for the chips you mentioned state they have 8-bit DACs for each color, yet you keep saying it's 16-bit. That's pretty funny.[/quote]
You know what is funnier... the same datasheet with 5-bit red input, 5-bit blue input and 6-bit green input!
-D- wrote:
Yes, using 256 colors it's possible for a smooth gradient, but as you've stated, highly impractical. Try viewing the image you linked to on an AGA screen, and it will look like ass.
Look at the RED bit in one AGA screen, BLUE bit in another and GREEN in another and they look IDENTICAL to the PC in AGA!
-D- wrote:
Due to the very nature of how HAM works, you get fugly looking images, gradients included. This even has nothing to do with HAM8 not being a 24-bit output in the sense of displayable colors, regardless of the internal palette.
No HAM8, just regular AGA screen mode, any number of colours you like. 256, 32, 8.
Choose a different 24-bit palette entry value for each colour where only the LSB's are different.
With an AGA paint package, paint the background in one of these colours and write your name using the different colours.
Look at it on your XRGB monitor... yep cool... "-D-"
Now use a 16-bit scandoubler... but wait... I cant see anything... everything looks the same colour!!
ARRRGHHH!!!
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One other thing I should point out is that the scandoubler is not (by default) a frequency shifter, and so PAL screens are still 50Hz and may not display on some LCD panels.
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OK, I will try it... and if I have to eat shoe, I will :-p
And I agree, a 16-bit scandoubler might not be ideal for AGA, if indeed it effects the internal palette and not just the "amount" of displayable colors, admittedly I'm not an expert on this.
BUT, I can't find anything in the datasheet for the AL250a indicating a castrated input, however, I'm open to correction.
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AGA isn't capable of *outputting* smooth gradients, since it can't simultaneously display the amount of colors necessary for that
Dead wrong. 100% incorect, false and untrue. You should be ashamed of yourself.
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-D- wrote:
BUT, I can't find anything in the datasheet for the AL250a indicating a castrated input, however, I'm open to correction.
http://www.averlogic.com/admin_en/product_en/pic8/540738.pdf (http://www.averlogic.com/admin_en/product_en/pic8/540738.pdf)
Look at the number of bits on the input on the diagram on page 1. 16-bits
-D- wrote:
if I have to eat shoe, I will :-p
Nowt bad about being wrong mate, happens to me several times a day, you just pick yourself up, learn from it and get on with it. Makes you a stonger engineer.
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alexh wrote:
http://www.averlogic.com/admin_en/product_en/pic8/540738.pdf
Look at the number of bits on the input on the diagram on page 1. 16-bits
OK -- you are correct. I agree this is sub-optimal...
@JosephC
Dead wrong. 100% incorect, false and untrue. You should be ashamed of yourself.
Get over yourself. 256 color gradients, yes. HAM8 gradients look fugly with an excess of color fringing/bleeding.
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-D- wrote:
Get over yourself. 256 color gradients, yes.
No, no, no.
Not just 256 colour gradients. (Although these are the most obvious)
Any AGA screen.
If the colours use the lower 3-bits of each colour component, and there are several of them separated by only these bits. They will appear as one colour.
It is particularly noticable on AGA 3D demo's with light shading, AGA monochrome demo effects, AGA 2D pictures with flesh tones or halo's (like say from a candle).
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alexh wrote:
-D- wrote:
Get over yourself. 256 color gradients, yes.
No, no, no.
Not just 256 colour gradients.
Any picture.
If the colours use the lower 3-bits, and there are several of them. They will appear as one colour.
Ugh... there seems to be a bit of misunderstanding going on here.
Issue one -- In the above reference (@JosephC), my intention wasn't to say that a 256 color gradient would look as it should with a 16-bit SD, only that while AGA itself (viewed normally) is definitely capable of 256 color smooth gradients, HAM8 gradients don't look right because of the way HAM works.
Issue two -- I figured that since AGA is only capable of displaying 256 simultaneous colors (for the most part, outside of HAM modes), that therefore a 16-bit SD should be fine... not taking into consideration that a 16-bit SD could actually mess with the palette capabilities (it must "round off" certain colors, so to speak). I clearly understand the difference between 16 and 24-bit in regard to displayable colors, but didn't consider that the palette (in the case of AGA, 24-bit) might also be affected. Therefore, I stand both enlightened and corrected in this regard.
Also, I determined (from a quick browse of the datasheets) that the Averlogic SD was 24-bit, after noticing the 3 8-bit DACs. I stand corrected here also, as alexh is right, the input is indeed 16-bit.
My apologies to the thread.
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alexh wrote:
-D- wrote:
BUT, I can't find anything in the datasheet for the AL250a indicating a castrated input, however, I'm open to correction.
http://www.averlogic.com/admin_en/product_en/pic8/540738.pdf (http://www.averlogic.com/admin_en/product_en/pic8/540738.pdf)
Look at the number of bits on the input on the diagram on page 1. 16-bits
-D- wrote:
if I have to eat shoe, I will :-p
Nowt bad about being wrong mate, happens to me several times a day, you just pick yourself up, learn from it and get on with it. Makes you a stonger engineer.
Cheers. I came out guns blazing, only to feel like an ass. Sorry guys :lol:
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Maybe someone can find or make up a graphic that shows a 256 8bit single colour gradient next to the equivalent using only 4 and 5 bits.
That way people can see the difference for them self without having to resort to fiddling with screen modes.
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nBit7 wrote:
Maybe someone can find or make up a graphic that shows a 256 8bit single colour gradient next to the equivalent using only 4 and 5 bits.
That way people can see the difference for them self without having to resort to fiddling with screen modes.
I'd be more interested in someone using one to run Zool2 AGA, Gunship 2000 AGA or UFO Enemy Unknown AGA and letting us know if they are "aware" of any problems when playing a game.
I'm sure that squinting at hi-res static screens will reveal obvious differences, but I wonder if the naked eye when confronted with scrolling backdrops and fast moving sprites will detect any problems. I use a SDFF (internal) in my A1200T and I haven't noticed any problems. Granted, most games are ECS and I haven't tried to compare the cutput of the SDFF on a VGA monitor with my 1081 connected to the usual video out.
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HAM8 gradients don't look right because of the way HAM works.
You have it all backwards.
HAM8 gradients are the only thing that do look right because of the way HAM8 works.
When the color changes wildly from 1 pixel to the next you get fringing on HAM8. When the colors are a smooth gradient you get beauty and elegance on HAM8.
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Darrin wrote:
I'd be more interested in someone using one to run Zool2 AGA, Gunship 2000 AGA or UFO Enemy Unknown AGA and letting us know if they are "aware" of any problems when playing a game.
Probably not. You'd just shrug off having fewer colours as being part of the game. DCE FlickerMagic/ScanMagic internal scandoublers are I think 16-bit and they are widely used. I think only recently did it come to light that they were (but I am probably wrong and when they came out everyone hated them, but then forgot the limitation over time ;-))
I would imagine that using WinUAE with the aforementioned games and switching to a 16-bit direct colour mode may have the same effect as a 16-bit scandoubler. Try it.
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Darrin wrote:
nBit7 wrote:
Maybe someone can find or make up a graphic that shows a 256 8bit single colour gradient next to the equivalent using only 4 and 5 bits.
That way people can see the difference for them self without having to resort to fiddling with screen modes.
I'd be more interested in someone using one to run Zool2 AGA, Gunship 2000 AGA or UFO Enemy Unknown AGA and letting us know if they are "aware" of any problems when playing a game.
I'm sure that squinting at hi-res static screens will reveal obvious differences, but I wonder if the naked eye when confronted with scrolling backdrops and fast moving sprites will detect any problems. I use a SDFF (internal) in my A1200T and I haven't noticed any problems. Granted, most games are ECS and I haven't tried to compare the cutput of the SDFF on a VGA monitor with my 1081 connected to the usual video out.
Dunno... probably not for the most part, but I suppose the best would be a back to back comparison. I ran the internal DCE unit for years and thought it was great, though now I'm wondering if it skewed my impression of AGA capabilities (like HAM8 photo viewing).
Bummer I sold it, as now would be a great time to make some comparisons... especially if the unit is in fact 16-bit.
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To be able to reproduce the full 16M colours would require using more than 24bits (3*8bits) at the analogue to digital converter (ADC).
This is because it would near impossible to line every analogue step with the corresponding digital. For example suppose the analogue Red signal with 256steps (8bit) went from 0Volts for off to 1 volts. Then each step will be 1/256 Volts or 3.9mV (0.0039V).
colour value = Analogue voltage level
-------------------------------------
0 = 0V
1 = 3.9mV
2 = 7.8mV
...
253 = 992mV
254 = 996mV
255 = 1000mV (1V)
If the DAC was only looking at a range of say 0 to 995mVolts
it is clear that it would not correctly detect all the levels. This is even before we consider all the various types of distortion.
If we sampled with say 16bits per colour and make the digital capture range slightly larger than the analogue then we can capture the full range of colours.
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-D- wrote:
I ran the internal DCE unit for years and thought it was great, though now I'm wondering if it skewed my impression of AGA capabilities (like HAM8 photo viewing).
Bummer I sold it, as now would be a great time to make some comparisons... especially if the unit is in fact 16-bit.
You are on this side of the pond and you let an internal SD/FF get away???
The only time I saw one over here was at the EyeTech booth at the 2001 Gateway show. Alan Redhouse did not want to schlepp remaining stock back to the UK, so he offered either the internal or external for about US$60. I couldn't afford both, so I picked the external because it works on any Amiga, and I've been regretting the choice ever since.
That external SD/FF, and probably this new one too, adds a lot of noticeable noise to the image because of the extra Analog->Digital conversion. Still looking for an internal unit for my A1200, after all these years.
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I played around a bit with WinUAE (AGA modes) and the gradients image alexh linked to earlier.
Cutting out the 0-255 color diagonal gradients and viewing them with PPaint, there is a loss of color (255 color gradients aren't perfectly smooth), however they look better than I expected, and the color loss in this case could be down to PPaint image handling/conversion process. The 256 color red sphere looks amazing since the banding is less perceptible.
While viewing the same image, switching WinUAE video mode down from 32-bit to 16-bit setting produced a horrific color loss, easily seen.
There was obvious banding viewing the reverse-aligned and RGB cube images, but this was to be expected since they use more than 256 simultaneous colors.
I played around with the HAM viewer, and as I recalled, gradients looked rather poor IMO. Yes, they can be somewhat smooth, but the weird HAM effects (looks like over-saturated colors and blurring) are obvious.
These are my observations after a quick test, and I realize there are too many variables involved to make any "definitive" statements (plus I'd really like to attempt some better testing using a "real" AGA machine).
My error lied in how I was viewing the "16" and "24" bit terminology in relation to Amiga video display, vs how alexh and others (admittedly more technical) usage. Normally, a distinction isn't made when referring to internal palette vs amount of displayable colors, since they are almost always the same. AGA is a bit unusual in this regard, having an 24-bit color palette, yet usually only capable of what would normally be termed an 8-bit (256 simulaneous colors) output (though from a 24-bit palette). I think this is why there is so much conflicting information abound on the subject. For example, HAM8 drivers for Shapeshifter are referred to by their authors as being 15-bit, simply in reference to the potential of displayable colors, not in reference to the internal palette. So the disparity here is really down to terminology. (And I still think it's a little unfair to say AGA is a 24-bit output without first clarifying things.)
Anyhow -- I'm not sure the DCE internal unit is 16-bit, at least not in the same sense as viewing, say, a 256 color blue gradient in WinUAE/AGA, and then switching to 16-bit. I used to do quite a bit of photo-related things using both HAM and 256 color screenmodes, and probably would have noticed such a terrible color-loss. Alexh and and I both agree that the GPS chip on that unit is certainly 24-bit, and if the output has been reduced it's not discernable from looking at the hardware specs.
Any SD that is 16-bit I would certainly avoid for AGA, though.
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hardlink wrote:
-D- wrote:
I ran the internal DCE unit for years and thought it was great, though now I'm wondering if it skewed my impression of AGA capabilities (like HAM8 photo viewing).
Bummer I sold it, as now would be a great time to make some comparisons... especially if the unit is in fact 16-bit.
You are on this side of the pond and you let an internal SD/FF get away???
The only time I saw one over here was at the EyeTech booth at the 2001 Gateway show. Alan Redhouse did not want to schlepp remaining stock back to the UK, so he offered either the internal or external for about US$60. I couldn't afford both, so I picked the external because it works on any Amiga, and I've been regretting the choice ever since.
That external SD/FF, and probably this new one too, adds a lot of noticeable noise to the image because of the extra Analog->Digital conversion. Still looking for an internal unit for my A1200, after all these years.
Yeah, what can I say, but bummer on my part. I sold it years back when I felt WinUAE was at a sufficient point of replacement. At the time, I was using it with a really nice Trinitron, and the quality was fantastic. (Aside from the 50 Hz PAL flicker, which I'm VERY sensitive to.)
I'm still searching for something to adequately replace it, since I've once again been smitten by the "oldies"... I've recently started putting my A1200 back together (just picked up a PG upgraded Apollo 1260) solely for the purpose of watching demos. This time, I won't be selling anything, that's for sure. :-)
There's a unit on Ebay (http://cgi.ebay.com/RGB-CGA-to-VGA-480i-Componet-to-VGA-Converter-Scaler_W0QQitemZ260171667083QQihZ016QQcategoryZ41999QQrdZ1QQssPageNameZWD1VQQcmdZViewItem) that looks pretty good, except that one of its "features" is converting 50 Hz to 60 Hz, which might (to one extent or another) screw up all those lovely PAL demos. And then there's this guy (http://cgi.ebay.com/Arcade-RGB-CGA-to-VGA-Converter-Cherry-Masrter-Jamma_W0QQitemZ150174298212QQihZ005QQcategoryZ13718QQrdZ1QQssPageNameZWD1VQQcmdZViewItem), which doesn't convert from 50 to 60 Hz, but may be more of a pain to setup. The only quality scalers I've found cost an arm and a leg.
Ideally, I'd love to have my old internal DCE unit back + quality CRT for demos, and an LCD for WB-related things (to cut the eyestrain).
It's a real drag they're so rare and coveted these days... I dunno if it would be practical anymore (or if the parts are still available), but I bet DCE could probably sell a couple hundred units.
One positive thing to consider though, the internal unit runs really hot, as do the custom chips that are covered up by it. Might have an effect on longevity, which isn't an issue with your external version. Also, I found it to be kind of a PITA in a desktop case. (Between the IDE-Fix "Express" and the SD, 3 custom chips were covered up, LOL.)
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-D- wrote:
One positive thing to consider though, the internal unit runs really hot, as do the custom chips that are covered up by it. Might have an effect on longevity, which isn't an issue with your external version. Also, I found it to be kind of a PITA in a desktop case. (Between the IDE-Fix "Express" and the SD, 3 custom chips were covered up, LOL.)
Yes, those are very good points, especially about the DCE internal. Looks like the Micronik Scandy 1200 was a different design approach, with 2 small bare/passive chip 'snap-ons' and only memory and 2 big custom(?) chips on the main PCB snap-on:
http://www.amiga-hardware.com/showhardware.cgi?HARDID=373
I wonder if a design like this could be resurrected; maybe 3 passive ventilated snap-ons and a PCB that could be placed out of the way. Seems like it should be even simpler than an external unit if you can grab the digital RGB data, saving 3 A/D converters, and the image quality would be MUCH better.
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Cutting out the 0-255 color diagonal gradients and viewing them with PPaint, there is a loss of color (255 color gradients aren't perfectly smooth), however they look better than I expected, and the color loss in this case could be down to PPaint image handling/conversion process. The 256 color red sphere looks amazing since the banding is less perceptible.
remember that the gradients are restricted to 256 different colors at once. But those 256 colours can be any out of the 24bit.
For 24bit colour RED GREEN and BLUE each can be set at 256 (0-255) levels (intensities)
If you were to use a gradient that used only one of those colours (eg. Black to RED, but not Black to RED to White). In this case you would grantee that you didn't go over the 256 different colours at once limmit. Then it can be displayed in 256 colour AGA with no loss what so ever, as there are only 256 red levels (in 24bit graphics) and AGA can display every one of them.
An ECS or OCS amiga would only be able to display 16 levels of that gradient. 16levels leads to noticeable banding.
In an example where you had a gradient that went from Black to RED to White. You have a situation where you can have 256 levels getting to full red then another 255 levels getting to white.
RED to White is made by keeping RED at 255 and bringing up GREEN and BLUE together.
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count me in if I see it working on a miggy (although I can't imagine a reason not to)!
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nBit7 wrote:
To be able to reproduce the full 16M colours would require using more than 24bits (3*8bits) at the analogue to digital converter (ADC).
Not that it matters, but internal scandoublers, like the Arxon and Petsoff and DCE FlickerMagic / ScanMagic etc. dont have ADC's. They get their RGB information in digital form direct from the chips (Lisa/Denise).
For the best picture quality and colour representation the AL250a could be used on it's own directly attached to the Lisa/Denise chips without an AL875 ADC, but it would be and "Amiga only" solution. You'd need a different one for ECS and AGA Amiga's. It wouldnt be worth it. And it would still be 16-bit ;-)
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Are these still avalible? :-?
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Simply load the demo "Rain" by The Black Lotus. The clouds will look crap with 16bit scandoublers like DCE/phase5 CV3D scandoubler.
In contrast Arxxon or Picasso4 will look perfect.
BTW, AGA has a 24bit palette. That means I can make smooth transitions of just one bit. And it's noticeable if you are used to painting and computer graphics. It doesn't matter if you are showing just 16colours, it won't look smooth (read right) with a 16bit scandoubler!
Regarding HAM8, you can make very smooth transitions just changing one bit. The problem is not smoothness, the problem is changing from one colour to another one completely different.
In addition to that you should remember that AGA is not limited to 256 colours. Each few pixels the copper can change the palette.
If you can't notice the difference of AGA running through a 24bit scandoubler and a 16bit go to an eye specialist because you have some kind of visual problem
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Does anyone have information about the Micronik Scandy 1200 is it 16bit also and would a CM-345S (http://www.amiga.org/gallery/index.php?n=1169=38)scan with 24 bit ? just curious as i would like a CM-345S for other consoles and own the scandy "soon"
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I'd definitely be interested in buying one - not bothered about it being 16-bit only as most of my games are non-AGA. If I choose to run an AGA game, I'd just hook the A1200 up to the telly via the scart.
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alexh wrote:
For the best picture quality and colour representation the AL250a could be used on it's own directly attached to the Lisa/Denise chips without an AL875 ADC, but it would be and "Amiga only" solution. You'd need a different one for ECS and AGA Amiga's. It wouldnt be worth it. And it would still be 16-bit ;-)
Now your'e talking! I'm not so sure about needing one for ECS, the A3000 has one built in, and the A500 and A2000 can use the old ICS Flicker Free Video 2, which seem a lot more plentiful than AGA internal doublers (I even have 2 of the ICS boards). And screw the A600 :)
So for 16-bit quality, you think the AL250a would work? Does it need external RAM?
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If you can't notice the difference of AGA running through a 24bit scandoubler and a 16bit go to an eye specialist because you have some kind of visual problem
No need to be an ass, at least I had the cojones to admit my mistake, instead of just disappearing. Once again, I've never stated AGA didn't have a 24-bit palette (or that a 0-255 red, green, or blue gradient couldn't be smooth utilizing 256 colors from said 24-bit palette). Also, never did I state that there isn't a difference betweeen 16 and 24-bit color. (Duh.) I simply didn't realize that a 16-bit scandoubler would actually castrate the palette, as opposed to only effecting the AMOUNT of displayable colors, and have since been corrected. It's a pretty honest mistake, considering how AGA is a bit (pardon the pun) different in this regard.
In addition, I still think HAM gradients look fugly (smooth or otherwise). They don't look good to me, as the colors appear over-saturated and blurry. This is simply a matter of personal opinion.
Clear as mud? :roll:
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hardlink wrote:
So for 16-bit quality, you think the AL250a would work? Does it need external RAM?
Yes, no.
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adonay wrote:
would a CM-345S (http://www.amiga.org/gallery/index.php?n=1169=38) scan with 24 bit?
I would think so, but it would be best to test empirically. They use the SmartASIC STV108 Scandoubler which can do 24-bit input.
http://www.amiga.org/gallery/index.php?n=1176=38
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alexh wrote:
hardlink wrote:
So for 16-bit quality, you think the AL250a would work? Does it need external RAM?
Yes, no.
Does anyone here have or can they get the full datasheet for the AL250a? Only the 'flyer' seems to be availabe. I am trying to determine if the are enough signals on the A1200 ADV101KP30 video dac, for which I have the full datasheet, to drive the blasted AL250 or the newer(?) AL251.
If this is possible, a very economical and low noise, but limited color resolution, internal A1200 SD/FF should be possible.
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hardlink wrote:
Does anyone here have or can they get the full datasheet for the AL250a?
http://www.ortodoxism.ro/datasheets/Averlogic/mXvqxzx.pdf
I am trying to determine if the are enough signals on the A1200 ADV101KP30 video dac, for which I have the full datasheet, to drive the blasted AL250 or the newer(?) AL251.
There are not enough signals on the video DAC. There are no SYNC signals. Also it is not the source of the signals.
That is why the DCE chips clip to the LISA (R[7:3], G[7:2], B[7:3]) and the ALICE (HSYNC, VSYNC) chips.
The AL251 is not newer, just different. Damn upgrade fever!!
If this is possible, a very economical and low noise, but limited color resolution, internal A1200 SD/FF should be possible.
It is possible, but no one with the technical capabilities to make it a reality is interested. It requires an investment of time and money that no one has. Add to that the loads of generic 24-bit RGB external scandoublers at £75-£95 ($150-$190), it's not a good place to be profit wise just now.
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Here's a list of (possible) vendors of the cm-345s (http://www.cypress.com.tw/distributor.html)
Not cheap though, here (http://www.normwandler.de/product_info.php?info=p44_SCART-to-VGA-Video-Scaler-CM-345S.html) it's being sold at 189 euros...
Though to me it can be worthwhile, since I have quite a vintage computer collection.
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oh, hell yeah! Though I've tried to e-mail this guy a few months ago, to no avail. Must have gotten the address wrong. Is there some sort of mailing list you could run on this, or just tick on the notify in this thread? (I've already smoked 2 1950 monitors, am now using my brothers old 1942 which is making a scary capacitor whine and jumps around a bit, making me think its on its last legs, and really DON'T want to dig up an old tv set, requiring me to not use my 800x600 resolution screen, and hope it can stabilize PAL games and play them missing the bottom of the screen)
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@alexh
Add to that the loads of generic 24-bit RGB external scandoublers at £75-£95
Do you think there is a 24bit version in that bunch that might be a canidate to get ported for Amiga? Maybe even just a datasheet a chip used in a 24-bit RGB? Can't seem to find much on the STV108.
Plaz
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Hi kvasir,
take time to change capacitors (even the non polarised one) and diodes. I won't cost more than 25$ and it's easy to do.
For the 1950, check the equivalent with HR Diemens or other flyback makers.
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I'll have to ask my brother if I can do that. Meanwhile, I've gotten ahold of a second A1200, that has some sort of scandoubler in it, so I'm using a Mitsubishi Diamond Pro 91TXM 20" VGA monitor. Though I had to trade my super72 800x600 res for a PAL hires laced 724x566 screen. (Even with MonED and MIprefs I couldn't stabalize an image that size) Would still like to have an external scandoubler, though. This way I could still record AVI/MPG clips to VHS, and still use my nice 20" monitor doing it! (My older 1200 is set up with the old 1942, using an NTSC res, pretty much for recording animations to tape.)
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OK, I've finally gotten ahold of one of these things, arrived earlier this week and I've been playing with it a bit. It does get the scanrate to where my Mitsubishi Diamond Pro 91TXM monitor can display Amiga output, however there is a green tint too it. I believe this was touched on earlier in the thread, and I wanted to get other ppls opinion of whats going on with it. Apparently, the 16 bit input expected from the chip is split up between 3 channels as Red: 5, Green: 6, Blue: 5, Where AGA exports 24 bit signal as Red: 8, Green: 8, Blue: 8. I would think this would cause a drop in green tint, and overpowering of blue and red, but I guess my thinking was backwards here. The gentleman making these things seems eager to get an Amiga compatable version working, and was thinking of somehow dropping the extra green bit before it reaches the chip. (I think, I'm not too good at this level of digital electronics) My solution was to solder together 2 vga connectors with a resistor on the green line to bring it down to the same level as the red and blue, and being too lazy to work out the math, was actually going to solder 3 different variable resistors on the RGB lines and adjust the VGA display until it matched what was on my TV through the composite port, then measure the resistance accross the green pot and E-mail him the value for future units. I've uploaded 2 pictures here, of a test pattern (apparently from sweden, just something I grabbed off google images by typing "color test pattern" :-D ) and will edit this post or just add another one when/if they're approved. 1 is of the NTSC tv displaing the test image, and the other is the monitor displaying the same image. Any corrections in what I think is going on here would be appreciated, as I'm so good at hardware engineering that I currently hold a telemarketing job trying to sell cable telephone to people that don't want it. :-D
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I would love to order one of these. I think I emailed this guy several months ago about buying one, but I havn't heard much since then. Is he still making them? Is there a huge waiting list? I guess I sort of just moved on. If anybody knows anything, please let me know. Thanks.
Barney
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OK, looks like the 2 pics I uploaded got approved.
This is the image on my TV set from the comp. output (http://www.amiga.org/gallery/index.php?n=2732)
And this is the green tinted scandoubled output on my VGA monitor. (http://www.amiga.org/gallery/index.php?n=2731)
I should mention while the "waiting list" on these seems pretty reasonable, he's reluctant to sell to any A1200/ A600 owners until everything gets hammered out. (I plan on testing this out on an old A1000 I have access to @ the end of the month)
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Well if the originally suggested price range on this remains the same then Jens will have some serious competition if the guy finally gets it working.
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Still swapping E-mails with this guy, he's currently looking for an Amiga 1200, and was wondering if anybody in SW Virginia would be willing to sell or at least let him use one to get this thing working?
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I'm in Northern VA, but wouldn't mind lending my 1200 in exchange for a sweet deal on a completed unit ;)
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@Tone007
Come on man take one for the scene here... help us out...
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...I thought that's what I was trying to do.
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Well, my 1200 is on its way to Roy's. Hopefully he can figure out the issue.
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just in case no one else does, I would like to say thanks for helping him on this... I've been waiting for one of his Scandoublers too...
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Less than a week and my 1200 is back, along with the scandoubler Roy had no problem tuning up for the 1200.
Definitely nice for playing those 15khz mode games on a VGA CRT.
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tone007 wrote:
scandoubler Roy had no problem tuning up for the 1200.
Definitely nice for playing those 15khz mode games on a VGA CRT.
Cough it up tone007, review, photos of unit and such.
Was gonna spend the $ for the IndivisionAGA FF on my A1200 that I barely use. Not sure which route to take...
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does this mean they are ready? can i buy one yet? how much are they?
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This sounds really interesting, as someone who would love to get a scandoubler for his A1200 but the Indivision is too expensive at the moment, where is it possible to order or contact the guy doing these?
Cheers!
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OK, finally managed to dig up enough free time to get this post out here, Got a new unit from Roy about a week ago, and he changed the resistors on the input end of it for the 1200, which has fixed the green "tint" problem to a minimum, though there still is a slight bit of discoloration noticable when the overall pallete is darker. A bit muddy on interlaced screens, too. That said, it works very well for most games I've tested. (One of the reasons for my lack of free time time is the fact I couldn't run half my games due to needing dblntsc and multiscan compatability for my monitor, and was going through withdrawl :-D ) It does result in some color drop due to 24-16 bit conversion, and as such would be ideal for an Amiga 1000, 500, 2000, 600, and 3000 if it didn't already have a scandoubler. AGA does do 24-bit, and results in the color loss, but this isn't terribly noticable. Its best to keep the unit in PAL mode, as he uses a jumper to switch between the Pal/Ntsc, and PAL in NTSC will result in the familiar cropping of the bottom of the screen. NTSC when the scandoubler is in PAL doesn't have any noticable problems, however. Only other thing for 1200 users to consider is if you use the composite out rca next to the rgb port, the 23 pin adapter he uses overlaps it to where it can't be used, unless you cut the screw tab off of that side. (One reason I wanted an external scandoubler is so I can use my 20" VGA monitor while still sending output to my VCR.) So far, I've moved all the scandoubled screenmodes into my sys:storage/monitors and stuck with NTSC/PAL in devs:monitors, saving lots of memory there. For what he's charging for these things, its a pretty good deal!
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I was on the waiting list for one of these units too but I bought an Indivision AGA for my 1200 almost 2 months ago and totally love it :-D
I know the price is more than double for the Indivision unit but from what I'm reading so far..ya get what you pay for....
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So are these available? If so where from and how much?