[Coco] Coco Monitor Question

Michael Graham mkgraham at gmx.com
Fri Sep 7 10:13:08 EDT 2012

I use a PCjr monitor with my CoCo 3, but I opened it up and bypassed the 
digital input circuitry (that is, all of the logic chips in the RGB 
signal path), which effectively turned it into an analog RGB monitor, 
giving me all the colors the CoCo can produce.  I have a feeling there 
are some impedance matching issues going on, but it's still much clearer 
than composite.


On 9/7/2012 8:50 AM, Frank Swygert wrote:
> For anyone interested, the Commodore 1084 Magnavox equivalent is the 
> 8CM515. Just remembered that! I think the 1080 Maggie equivalent is an 
> 8CM505.
> Bill, he can get 64 columns with the composite output but that's about 
> it. If one of you run across an old PC CGA type monitor you can wire 
> it directly into the CoCo but will only get a few colors from the 
> digital RGB monitor (PC type). But as I said, good for text, and no 
> extra circuit board needed. EGA monitors will also sync down to the 
> 15.7 kHz sync signal used by the CoCo RGBA (A=Analog -- similar to CGA 
> but will produce more colors).
> Monochrome TTL monitors can be connected, I think, but also require a 
> special cable with a circuit to combine RGB into a single video feed. 
> At least I seem to recall some people doing that!
> It's hard to find the old Mono/CGA/EGA monitors now. I believe one of 
> the expensive Sony Multi-Syncs will still go down to 15.7 kHz, but I'm 
> not sure...
> Here's a site showing most monitor pin-outs:
> http://www.monitorworld.com/Cables/video_standards.html
> Has everything for PC/Apple/Sun, but no Commodore or other brands (a 
> couple IBM only standards).
> -------------
> Date: Fri, 7 Sep 2012 09:23:13 -0400 (EDT)
> From: Bill Pierce<ooogalapasooo at aol.com>
> Thanks Frank, He already has the composite monitor conected but can't 
> see 80column in OS9. He wants to try the RGB. Still don't know which 
> one he has
> -----Original Message-----
> From: Frank Swygert<farna at amc-mag.com>
> To: coco<coco at maltedmedia.com>
> Sent: Fri, Sep 7, 2012 6:02 am
> Subject: Re: [Coco] Coco Monitor Question
> The Commodore 1080 and 1084 are both made by Magnavox, but I forget 
> the Maggie
> model number. The 1080 needs the sync circuit modified as described in a
> previous post, the 1084 will automatically adjust sync and work as is. 
> I agree
> with Bill -- the 1084 is one of the most versatile classic RGB 
> monitors, will
> work with a PC also IIRC. About the only one more versatile would be a 
> Sony
> Multi-Sync, but they cost a lot more back then! The later Multi-Syncs 
> wouldn't
> sync down to the level that the CoCo used though (standard CGA, but 
> analog
> instead of digital). Yes, you can connect a standard CGA monitor (if 
> you can
> find one!), but you won't get the range of colors with the digital RGB 
> (CGA)
> monitor. Still, it's good for text based applications.
> -- 
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