vwestlife
Veteran Member
After the C128 ended production, Commodore had no reason to need support for TTL RGB(I) video anymore, so the 1084 monitors made after then only support analog RGB.
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Cheapest way to display CGA
- Thread starter JonB
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tipc
Banned
I have a 1084s that worked wonderfully with a 128 I got rid of. Plugged it into a CGA card, and IIRC the sync was all messed up. I never got around to opening it and twisting the triimpots.
Specifically, there are 1084/s's that won't work w/anything but analog color? I guess it has nothing to do w/my model, as the monitor did work w/a 128, which is clearly rgbi color. Was once told by someone once that any 1084/s would work w/CGA.
Specifically, there are 1084/s's that won't work w/anything but analog color? I guess it has nothing to do w/my model, as the monitor did work w/a 128, which is clearly rgbi color. Was once told by someone once that any 1084/s would work w/CGA.
vwestlife
Veteran Member
They were wrong. This site shows numerous 1084S variants that support analog RGB only (scroll sideways):
http://gona.mactar.hu/Commodore/monitor/Commodore_monitors_by_model_number.html
Scali
Veteran Member
What about their own PCs then?
I've had quite a few, and I never had one that did anything but analog RGB, IIRC.
Didn't those all have composite? (I don't know, I've only ever seen one or two)
Scali
Veteran Member
Composite and RGBI.
SpidersWeb
Veteran Member
The 1084S-P and P1 are common here, and they all have a DIN plug on the back for RGBI TTL. Most I see seem to come from sellers also selling Amiga 500's etc.
It's certainly worth investigating if you're in a market where these displays are common and going cheap.
Nobody should ever use composite on a PC, I think that was only ever included for people who couldn't afford a monitor. Commodore PC's generally had a 9 pin connector with support for MDA, CGA, and Plantronics (16 color CGA). I don't think these shipped with 1084's though.
It's certainly worth investigating if you're in a market where these displays are common and going cheap.
Nobody should ever use composite on a PC, I think that was only ever included for people who couldn't afford a monitor. Commodore PC's generally had a 9 pin connector with support for MDA, CGA, and Plantronics (16 color CGA). I don't think these shipped with 1084's though.
I wouldn't expect so either. But, I can't imagine what they did come with.
Scali
Veteran Member
SpidersWeb
Veteran Member
8088 MPH begs to differ on that one
lol after I hit submit, I thought "somebody is going to mention 8088 MPH aren't they"
g4ugm
Veteran Member
All this discussion about "Composite" and assumes a standard CGA adaptor. From what I remember the PPC512 and PPC640 which are the computers in question, do not have composite signals. They have a video adaptor on the mother board which is switchable between CGA and MDA,
http://www.computinghistory.org.uk/det/24547/Amstrad-PPC-512D/
so composite is no use to the author. They need TTL RGBi to analogue RGB....
http://www.computinghistory.org.uk/det/24547/Amstrad-PPC-512D/
so composite is no use to the author. They need TTL RGBi to analogue RGB....
SpidersWeb
Veteran Member
Yes, I believe overall we're suggesting a Commodore 1084S (or similar) with the TTL option as a possible low cost alternative, or an RGBI to SCART circuit (lots of designs online).
The composite just came up as an off topic regarding the need for newer 1084's to retain the TTL port for compatibility with their line of personal computers.
The composite just came up as an off topic regarding the need for newer 1084's to retain the TTL port for compatibility with their line of personal computers.
Scali
Veteran Member
Well, this page: http://computers.mcbx.netne.net/portables/ppc512/index.htm#video
Indicates that pin 7 has a 'mono' signal. That is likely the composite output, as mentioned elsewhere... Some systems output composite on pin 7 of the RGBI (IBM does not).
g4ugm
Veteran Member
Check the Mono Display Adaptor pin outs. That's the Mono Display adaptor Video when the machine is in MDA mode. That's why it says "Mono Video". There are switches to set the card in CGA or MDA. Some how the on-board LCD display both, badly if I remember properly. Been a long time since I had one of these. I can't even remember it I had a separate CGA monitor or if I used the Phillips CM8833MK2 I bought for my Atari with it...
tipc
Banned
there seems to be some confusion as to what RGBI means. RGBI implies a "digital" or TTL monitor, one that accepts TTL color inputs. Highs and lows, no inbetweens. And RGB monitor is (except for some weird contraption, not stating they exist, but who knows) an analog monitor - the color inputs can vary from zero volts to whatever the upper maximum is (which presumably will be full R, or G, or B. Anything less then full is lower intensity R, or G, or B).
There's no such thing as an analog RGBI monitor. The 'I' is only for additional intensity, thereby increasing the number of color levels/possibilities. The degree to which voltage is applied on an RGB (analong) monitors color input constitutes the extra intensity.
A CGA monitor is RGBI. Not sure, maybe IBM was the first company to implement such a monitor. Very limited color possibilities. In binary, 2^4 (4 because there are 4 inputs, R, G, B, and I) makes 16, and that's how many color combinations that are possible. An analog/RGB monitor has unlimited color possibilities (limited by the amount of memory dedicated to video).
Still don't understand how the 1084s isn't RGBI. Did the Commodore 128 output analog video? Will a Commodore 128 output to a CGA or equivalent monitor? Apologies if the question was answered.
Remember also many of the pre-EGA/PGC computers or video cards were also RGBI, but weren't CGA compatible, reason being they output more resolution. A Tandy 2000 cannot output to a CGA monitor, nor can a CGA card output properly to a Tandy 2000 monitor.
There's no such thing as an analog RGBI monitor. The 'I' is only for additional intensity, thereby increasing the number of color levels/possibilities. The degree to which voltage is applied on an RGB (analong) monitors color input constitutes the extra intensity.
A CGA monitor is RGBI. Not sure, maybe IBM was the first company to implement such a monitor. Very limited color possibilities. In binary, 2^4 (4 because there are 4 inputs, R, G, B, and I) makes 16, and that's how many color combinations that are possible. An analog/RGB monitor has unlimited color possibilities (limited by the amount of memory dedicated to video).
Still don't understand how the 1084s isn't RGBI. Did the Commodore 128 output analog video? Will a Commodore 128 output to a CGA or equivalent monitor? Apologies if the question was answered.
Remember also many of the pre-EGA/PGC computers or video cards were also RGBI, but weren't CGA compatible, reason being they output more resolution. A Tandy 2000 cannot output to a CGA monitor, nor can a CGA card output properly to a Tandy 2000 monitor.
The C128 has two video outputs. It would be the same if you had a PC with two video cards. One is analog, one is RGBI, and it is CGA compatible, at least in NTSC. I have no idea how it works outside of NTSC.
The issue with the 1084 monitor, isn't that it can't do it. It's that some of them can't do it (in my experience, most of them can't). Not all 1084 monitors are the same. Some have an RGBI input, some do not.
The 1084 was marketed for the C128, and, also the Amiga. When the C128 was cancelled, there was no reason to support it anymore. The Amiga does not have RGBI output.
The issue with the 1084 monitor, isn't that it can't do it. It's that some of them can't do it (in my experience, most of them can't). Not all 1084 monitors are the same. Some have an RGBI input, some do not.
The 1084 was marketed for the C128, and, also the Amiga. When the C128 was cancelled, there was no reason to support it anymore. The Amiga does not have RGBI output.
vwestlife
Veteran Member
Actually the Amiga does have RGBI output, designed to make it compatible with CGA monitors. Using the RGBI output restricts you to only 16 colors instead of the 4096 colors that you can get using analog RGB, so there is absolutely no reason to use the Amiga's RGBI output on a monitor that also supports analog RGB.
Which is why I had forgotten it was there. Thanks for the information!
ClassicHasClass
Veteran Member
Eh? Virtually every contemporary advertisement Commodore made for the 128 featured the 1902.
There were some 1084 monitors that aped the 1902 look, and I can well believe these were sold for the 128 later in the game to reduce the number of models in manufacturing, but the canonical 128 monitor was always the 1902 from the beginning. (And, as you say, the only monitor that is guaranteed to work with both the composite and VDC output. We shall not talk about the piece of crap that is the 1802.)
I said exactly the same thing until I did some searching around recently. I wanted to know why the 1084 would have RGBI.
No worries. I don't want to remember that one neither!