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Commodore 128 - RGB Video *and* audio?


walterg74

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Hi all,

 

Recently got a hold of a Commodore 1902A monitor, and was looking at how to connect the 128 to it for RGB display.

 

I will need to get a cable, sinne I already had one but for the 1084 type monitors with the D connector and not the round DIN one :(

 

Anyway, while looking at the pinouta, I see that while the normal video port (the one just like the C64 port) DOES have audio on one pin, that the RGB port connector does not!

 

So... how does one get RGB video *and* audio to the monitor...? Do you have to use TWO cables, or am I missing something..?

 

Thanks!

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Hi, there is someone on eBay that sells them for $10 + shipping: https://www.ebay.com/itm/Commodore-128-80-column-mode-Magnavox-80-RGB-video-monitor-cable-New-/300749532607

 

And yes, you use 2 cables. The RGBI is strictly for video, no audio. If you don't want 80 column, you don't have to use the RGBI output, but normally you can either connect both of the cables to the same monitor and flip the switch to go between 80 column and 40 or use a second monitor dedicated to both.

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Hi, there is someone on eBay that sells them for $10 + shipping: https://www.ebay.com/itm/Commodore-128-80-column-mode-Magnavox-80-RGB-video-monitor-cable-New-/300749532607

 

And yes, you use 2 cables. The RGBI is strictly for video, no audio. If you don't want 80 column, you don't have to use the RGBI output, but normally you can either connect both of the cables to the same monitor and flip the switch to go between 80 column and 40 or use a second monitor dedicated to both.

Thanks, I had seen those already but was curious about the audio part. Seems pretty lame that you need two cables, but I guess their rationale was people would only use it for business stuff and not need sound? (Really stupid...)

 

Also regarding the “switch” one you mention, I have one of those already but that one only switches between composite/color and 80 column but monochrome, and not RGB.

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I've got a 1902 (not A) and it has a button on the front to switch between the signals on the back. I don't have a lot of room, but when I setup my 128, I use 2 monitors with the 1902 being solely for the 80 column.

 

People of course make adapters so you can get rid of the CRT if you like for the RGBI and go to an LCD or something (VGA). Then maybe just use one bulky CRT for the 40 column since that is where it matters.

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I've got a 1902 (not A) and it has a button on the front to switch between the signals on the back. I don't have a lot of room, but when I setup my 128, I use 2 monitors with the 1902 being solely for the 80 column.

 

People of course make adapters so you can get rid of the CRT if you like for the RGBI and go to an LCD or something (VGA). Then maybe just use one bulky CRT for the 40 column since that is where it matters.

Thanks for the suggestions, will keep it in mind, but I guess I’m still stuck with the original question: how dontou get RGBI + Audio? From the looks of it, only solution is a “double cable” with the RGB connector and the standard video port connector on one end using just the audio pin? (And doesn’t that port even get oferride. When you flip to 80 column mode?). It’s funny because the RGBI port on the minitor also has an audio pin..

 

Also of doubt is how when you want to use chroma/luma with the 1902 I guess you also need a special cable.

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Thanks for the suggestions, will keep it in mind, but I guess I’m still stuck with the original question: how dontou get RGBI + Audio? From the looks of it, only solution is a “double cable” with the RGB connector and the standard video port connector on one end using just the audio pin? (And doesn’t that port even get oferride. When you flip to 80 column mode?). It’s funny because the RGBI port on the minitor also has an audio pin..

 

Also of doubt is how when you want to use chroma/luma with the 1902 I guess you also need a special cable.

 

My 1902 has the audio, video, chroma RCA round connectors as well as a D-sub for the RGBI on the back.

 

I only use 80 column for programming with Merlin 128 so can't say I've ever had a reason to have audio with it. Since it's only the VDC connected to 80 column, I don't think they ever intended games to be created on it. Of course I realize some people have done exactly that though ;)

 

Doesn't the 1902A have 2 round DIN cable ports, 1 being for the regular luma chroma audio and the other for RGBI?

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My 1902 has the audio, video, chroma RCA round connectors as well as a D-sub for the RGBI on the back.

 

I only use 80 column for programming with Merlin 128 so can't say I've ever had a reason to have audio with it. Since it's only the VDC connected to 80 column, I don't think they ever intended games to be created on it. Of course I realize some people have done exactly that though ;)

 

 

 

Doesn't the 1902A have 2 round DIN cable ports, 1 being for the regular luma chroma audio and the other for RGBI?

Yes, the 1902A has a round din for RGBI that includes one pin for Audio, And also a round din for LCA which strangely has no audio input (so another pita, specially bedause I aready had cables with separate chrims/luna but with RCA connectors.....) Edited by walterg74
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Yes, the 1902A has a round din for RGBI that includes one pin for Audio, And also a round din for LCA which strangely has no audio input (so another pita, specially bedause I aready had cables with separate chrims/luna but with RCA connectors.....)

 

That's odd, because the doc I looked at doesn't show audio on the RGBI connector, just the LCA. Doesn't the A in LCA mean audio? I don't know, I'm not an expert obviously. I did have a 1902A myself but tossed it for the 1902 because of a power button failure. That's why I have this link to the manual.

 

ftp://www.zimmers.net/pub/cbm/manuals/monitors/1902A_Monitor_Users_Guide_(English-French).pdf

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That's odd, because the doc I looked at doesn't show audio on the RGBI connector, just the LCA. Doesn't the A in LCA mean audio? I don't know, I'm not an expert obviously. I did have a 1902A myself but tossed it for the 1902 because of a power button failure. That's why I have this link to the manual.

 

ftp://www.zimmers.net/pub/cbm/manuals/monitors/1902A_Monitor_Users_Guide_(English-French).pdf

Yes, you are right I mixed the two up.

 

So LCA, existing cables don’t work, you need a new one with the round din at the end, and all signals ( ideo and audio) into it.

 

Rgb, just video (hence my original question) and goes back I guess to noboy thought of usong aidio with this mode

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Rgb, just video (hence my original question) and goes back I guess to noboy thought of usong aidio with this mode

 

Well, yes and no. Most people -- well, everyone -- I knew with a C128 had both the 40 column, which carries audio, and 80 column video cables connected to their monitor. Thus, sound is always available irrespective of video mode in use.

 

I would think, as stated above, 80 column mode was considered a "business" mode, and business computers of the time (e.g. IBM and clones) only had beeps for sound. As a result audio was most likely a minor consideration if at all.

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It seems CGA has two pins marked as No Connection. Those two are used on the C128 for Intensity to enable all 16 colours and Monochrome to get a 0.75 Vpp signal which also is what most combined 40+80 column SCART cables you'll find on eBay uses, meaning those won't produce any colours. The pinout has two ground pins, I don't know what would happen if one of those had been sacrificed for audio out when connecting it to a CGA monitor, if it wires together the TTL level RGB pins with what it thinks is a ground pin, meaning you'd send 5V backwards into the SID and fry it.

 

The alternative of course would be to skip Monochrome and get sound on that pin instead. I can't recall if the VDC is routed through RF as well. Otherwise people who don't own a RGB monitor, preferrably TTL capable, would have zero use of the 80 column mode.

Edited by carlsson
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VDC is not routed through RF. The only way to get a non-RGBI signal from the VDC is the monochrome output. I made a cable for this purpose to use with an Apple green-screen monitor for several years. Zed's interlace mode made it squeal badly enough to bother the dogs next door. I later got hold of a monitor which would take the RGBI output and so much was better in the universe.

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So that pretty much settles it. Commodore had four options about the VDC output:

 

1. Use a DE9 connector mostly wired according to CGA standard, using the spare pins for intensity and monochrome video. Users who wish to hear something from their C128 needs a second cable from the 5/8-pin output.

 

2. Like 1, but skip producing monochrome video in favor of audio output. Users without a RGB monitor or an external interface would have zero use of the 80 columns mode, but those who got a proper monitor get sound through the same cable.

 

3. Like 1, but reuse one of the GND pins for either sound or monochrome video, with the risk that if you connect a CGA monitor that isn't certified for C128 use, you might fry the SID or the VDC chip. Probably not a good solution in the long run.

 

4. Use a different connector with more pins, perhaps a DA15. It would even have enough pins to duplicate the luma and chroma from the VIC-II. Basically only Commodore's own monitors would fit before someone produces adapters for other standards. Small risk of connecting e.g. Macintosh monitors but if you are that stupid you probably shouldn't own a computer in the first place.

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  • 3 weeks later...

Hi all,

 

Recently got a hold of a Commodore 1902A monitor, and was looking at how to connect the 128 to it for RGB display.

 

I will need to get a cable, sinne I already had one but for the 1084 type monitors with the D connector and not the round DIN one :(

 

Anyway, while looking at the pinouta, I see that while the normal video port (the one just like the C64 port) DOES have audio on one pin, that the RGB port connector does not!

 

So... how does one get RGB video *and* audio to the monitor...? Do you have to use TWO cables, or am I missing something..?

 

Thanks!

 

Not sure if you still need a cable for your 1902A, but noticed this while searching eBay today for Commodore 128 items: https://www.ebay.com/itm/NEW-Vintage-Commodore-128-Magnavox-80-RGB-Video-Monitor-Cable-3-Ft-RARE/232625596147

 

Seems there are 2 available right now.

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  • 2 weeks later...

Not sure if you still need a cable for your 1902A, but noticed this while searching eBay today for Commodore 128 items: https://www.ebay.com/itm/NEW-Vintage-Commodore-128-Magnavox-80-RGB-Video-Monitor-Cable-3-Ft-RARE/232625596147

 

Seems there are 2 available right now.

If he runs out, this guy has apparently a bunch more eBay Auction -- Item Number: 3007495326071?ff3=2&pub=5574883395&toolid=10001&campid=5336500554&customid=&item=300749532607&mpt=[CACHEBUSTER]

Thanks guys, I had seen those and probably will get one, as I already had an RGB cable but it’s the one with the D connector for the 1084 monitor.

 

Do you know if anybody sells any ready-made chroma/luma video cables to use with this monitor and the 128/64? (I know one could make it as well, but wondering about ready-made)

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Hm, so you need a 8-pin DIN (C64/128 end) to a 6-pin DIN (1902A end) cable?

 

One of the finest makers of custom cables is Retro Gaming Cables in the UK, though they don't specifically list a such variant. Perhaps they would make one on demand, but then again you could solder it yourself and save a few dollars.

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I have seen some ready-made chroma/luma cables on eBay, not to mention original C= cables every so often. I have been making a couple S-Video cables here and there, though I have not been using a resistor. The ones I plan to make next time around will. Even without, the picture turns up nice and clean.

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