02/26/98: RGB pinout on a CoCo3? by pucc_unknown, | Category: Princeton | 4 comments - (Comments are closed)

RGB pinout on a CoCo3?

Date: Thu, 26 Feb 1998 16:48:22 GMT
Reply-To: Joseph Remy
Sender: COCO – Tandy Color Computer List
From: Joseph Remy
Organization: University of California, Davis
Subject: RGB pinout on a CoCo3?

Hi,

I was wondering if anyone knows what the pin outs on the RGB connector
under the CoCo3 is. And also if I could use that to hook up a Tandy CM-5
RGB monitor, by making a db9 adapter for it.

Maybe I’ll test it out and let you all know, if no one knows. :
furthering the CoCo knowledge base is always good!

~joe
jdremy [at] ucdavis [dot] edu

4 comments to RGB pinout on a CoCo3?

  • pucc_unknown

    Date: Thu, 26 Feb 1998 21:57:50 EST
    Reply-To: “James C. Hrubik Sr.”
    Sender: COCO – Tandy Color Computer List
    From: “James C. Hrubik Sr.”
    Subject: Re: RGB pinout on a CoCo3?
    In-Reply-To: <9802262003 [dot] AA04460 [at] acorn [dot] net>; from “Joseph Remy” at Feb 26,
    98 4:48 pm

    RGB output on CoCo is:

    1&2 = GND
    3 = RED
    4 = GREEN
    5 = BLUE
    6 = NC
    7 = SOUND
    8 = HSync
    9 = VSync
    10 = -5V * just noticed this goes to a PIA address pin on the 68B21;
    ???whatzit do??? I realize you don’t need to connect it to anything
    to make the monitor work, but what’s its significance?

    —Jim
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  • pucc_unknown

    Date: Thu, 26 Feb 1998 22:44:30 -0500
    Reply-To: Robert Gault
    Sender: COCO – Tandy Color Computer List
    From: Robert Gault
    Subject: Re: RGB pinout on a CoCo3?

    The intent was to be able to detect a working monitor. This option which would
    have worked for a Tandy monitor was not implemented in the ROM code.

    James C. Hrubik Sr. wrote:
    >
    > RGB output on CoCo is:
    >
    snip
    > 10 = -5V * just noticed this goes to a PIA address pin on the 68B21;
    > ???whatzit do??? I realize you don’t need to connect it to anything
    > to make the monitor work, but what’s its significance?
    >
    > —Jim
    >

  • pucc_unknown

    Date: Fri, 27 Feb 1998 02:30:18 -0600
    Reply-To: Carl Boll – System Operator
    Sender: COCO – Tandy Color Computer List
    From: Carl Boll – System Operator
    Subject: Re: RGB pinout on a CoCo3?
    In-Reply-To: <199802270356 [dot] VAA25585 [at] mail [dot] xnet [dot] com> from “Robert Gault” at Feb
    26, 98 10:44:30 pm

    While thinking of something else Robert Gault’s fingers typed:
    #>
    #> The intent was to be able to detect a working monitor. This option which wou
    ld
    #> have worked for a Tandy monitor was not implemented in the ROM code.
    #>

    Uh, no it wouldn’t according to the Tandy Service manual for the CM-8.
    According to the manual that line isn’t connected to anything inside the
    CM-8 so there is no way the CoCo could detect the Tandy monitor. This
    is likely the reason that the ROM code was never implemented. Tandy
    probably saved $.05 per monitor to not have the line implemented. This
    would be just about right. Of course there is always the possibility
    that the CM-8 is a repackaged of the shelf monitor too. Could be a
    Magnavox or Sony or one of many other brands just stuck into a new case
    with a different cable.

    #> James C. Hrubik Sr. wrote:
    #> >
    #> > RGB output on CoCo is:
    #> >
    #> snip
    #> > 10 = -5V * just noticed this goes to a PIA address pin on the 68B21;
    #> > ???whatzit do??? I realize you don’t need to connect it to anything
    #> > to make the monitor work, but what’s its significance?
    #> >
    #> > —Jim
    #> >
    #>


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  • pucc_unknown

    Date: Sat, 28 Feb 1998 09:57:28 -0600
    Reply-To: rogerp [at] INTERNOGO [dot] COM
    Sender: COCO – Tandy Color Computer List
    From: Rogelio Perea
    Organization: Deja News – The Leader in Internet Discussion
    Subject: Re: RGB pinout on a CoCo3?

    In article ,
    Carl Boll – System Operator wrote:

    > Uh, no it wouldn’t according to the Tandy Service manual for the CM-8.
    > According to the manual that line isn’t connected to anything inside the
    > CM-8 so there is no way the CoCo could detect the Tandy monitor. This
    > is likely the reason that the ROM code was never implemented. Tandy
    > probably saved $.05 per monitor to not have the line implemented. This
    > would be just about right. Of course there is always the possibility
    > that the CM-8 is a repackaged of the shelf monitor too. Could be a
    > Magnavox or Sony or one of many other brands just stuck into a new case
    > with a different cable.

    That line on the CoCo 3 RGB connector goes directly to a PIA so when a RGB
    monitor was connected there the plug should ground PIN 10, the CPU would
    fectet thru the PIA the presence of the RGB monitor and thus setup the color
    scheme to RGB.

    This, as stated on other messages, was not implemented in the ROM code that
    finally ended up in the CoCo 3. I have, somewhere shuffled in my CoCo papers
    and notes, a small Basic program that sets up the CoCo to allow detection of a
    rgound short at PIN 10 of the RGB connector and issues a RGB command upon
    hooking up a properly setup RGB plug.

    -=-=-=-
    Rogelio

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