[Coco] CoCo 3 to RBG...

[mike delyea]

Sorry I am not an electronics whiz by any stretch of the imagination but -
When hooking the coco to an Amiga 1080 monitor I used a 74ls02 to combine
HSYNC and VYSNC.  This gave me perfect 80 column text on the 1080.  Looking
back on my notes, this hack only provides composite sync.  Maybe this helps.

On Fri, Jul 22, 2011 at 8:36 PM, gene heskett <gheskett at wdtv.com> wrote:

> On Friday, July 22, 2011 08:25:43 PM gene heskett did opine:
>
> > On Friday, July 22, 2011 03:43:35 PM Steven Hirsch did opine:
> > > On Fri, 22 Jul 2011, gene heskett wrote:
> > > > Hit the menu button, up arrow to 4 and press the menu button again,
> > > > which will bring up a 2 choice and return menu, up arrow to
> > > > highlight the 1 and tap the menu button again,  voila!  English
> > > > menu's.
> > > >
> > > > But if we have to do this for every power up, it will be a bit of a
> > > > bummer. However, if it remembers the rest of the settings, probably
> > > > this won't be needed all that many times.
> > >
> > > My impression was that settings are non-volatile.  I never had to go
> > > back and reset the language at any rate.
> > >
> > > > Now, since Tim seems 'pre-occupied', I did find another video where
> > > > a capacitor and a pair of 510 ohm resistors was used to mix the
> > > > separate H & V syncs and feed the 'S' pin from an Atari ST.  But I
> > > > have no clue which polarity the sync sigs are coming out of an
> > > > Atari ST.  I could measure it of course since I managed to buy one
> > > > at a cocofest in Pittsburgh a decade back.  But I am inclined to
> > > > see if there are any spare gates in IC15 first. Or fly a bug on a
> > > > handy chip and use that. Time to go inventory my chips I guess.
> > >
> > > I'll be pleasantly surprised if you ever receive a response.  I no
> > > longer bother even trying with Chinese OEMs.
> >
> > Tim is the tech support at their American dealer-reseller, Jamma
> > something, which is where I bought the board, which it turns out I
> > could have saved a tenner by using fleabay.
> >
> > > Steve
> >
> > Cheers, gene
>
> Still no response from Tim.  I took another 74LS04 and set it on top of
> IC15, then discovered I was working on a PAL schematic, so the signals were
> moved around.  But it is working and is feeding that board a good solid 3
> volt sync negative signal.  And while the green screen phase is longer, and
> it looks as if something is leaking through, it is not coco video.  So, it
> may be that the 15 khz operation is achieved only with composite sync
> applied to the 'S' input.
>
> I suppose I need to find an ls86 and build that xor based combiner.
> Tomorrow maybe, if I can find an ls86.
>
> Cheers, gene
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> To refuse praise is to seek praise twice.
>
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