Rgb intensity line

Tony Duell ard.p850ug1 at gmail.com
Sun Apr 21 00:31:22 CDT 2019

On Sun, Apr 21, 2019 at 1:33 AM Bill Degnan via cctalk
<cctalk at classiccmp.org> wrote:
> I am fashioning an RGB cable from parts.  The computer (LNW80) does not
> send an "intensity" signal, it is only a 6pin rgb.  The magnavox rgb 80
> display that I wish to use to receive has a pin for an intensity signal.
> Other than "intensity" the rgb signals can be matched up.
> Question...what happens when a computer does not send an intensity signal
> to a display that has this input?  I will find out soon enough but I am
> curious to ask before I begin should anyone have a suggestion.  Do I need
> to add a resistor off of ground or something to fix it to something?

Assuming it's a TTL level RGB interface (which given the intensity line it
almost certainly is), I think there are several things you could do with that
intensity line. All will give a display but it will be different, so
pick the one you

1) Tie it low (so you always get the unintensified colours)

2) Tie it to +5V (preferably through a 1k resistor) (so you alway get the
intensified colours).

3) Connect it to one of the 'colour' signals. If you connect it to the G
signal for example, then any colour with green in it will be intensified.

4) Connect it to a logical combinaton of the colour signals. If you
connect it to the logical AND of R,G,B then white will be intensified
all others not. If you connect it to the logical OR of R,G,B then black
will be the only unintensified colour. This involves extra logic circuitry
and is probably not worth doing, but I include it for completeness.


> Bill

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