[Coco] Re: the XRGB-2+ upscan converter

[Charlie]

Question.: with this device can you have the coco hooked up with RGB and
composite at the same time, so that you can switch between inputs to get
artifact colors in coco2 games and the like?

Charlie

<RJRTTY at aol.com> wrote in message
news:19e.28844cfe.2e5d47ef at aol.com...
>
>
> OK ladies and germs,
>
>      I have received the XRGB-2 converter from Pacific Game Tech
> LTD. based in Hong Kong and here is the story:
>
>      When I first opened the box and looked at the owners manual
> my heart sunk.  The thing was written in chinese or japanese or
> whatever.  I figured I was in for a tough time for sure.  A closer
> look however revealed a lot of simple but informative line
> diagrams and isolated english words like "RGB" and
> "Video" occuring at strategic places throughout the manuall.
>      The first thing I did was try the simplest hookup, namely
> composite video in.   One of the concerns I had was that this
> device might use the same chip and technique of the infamous
> Matco converter.  That thing was no better than a hookup to a
> standard TV.  When I connected this box up and powered up
> the coco, the quality of the output was equal to that of the CM-8!!!
> I am not exaggerating.  I dont know how they did it, but they
> got the same bandwidth through that composite video port as
> the CM-8!!  I guess this device is good enough and the CM-8
> is poor enough so that they endup similar in performance.
> The only significant difference in performance i could find between the
> two was when the color-burst signal is turned off for
> monochrome operation.  This is the code I used:
>
> 10 poke &hE033,16 :poke &hE03C,19 :poke &hE045,19
> 20 width 32 :palette 12,63 :palette 13,0 :cls
> 30 width 80 :palette 0,0 :palette 8,63 :cls1
>
> This code turns the color burst signal off and sets up an 80-column
> screen with white text on a black backround.  The XRGB converter
> would either flicker at a rate of about 3 or 4 times a second
> or would stablize and wash out with artifact colors.  It's like
> it could not decide were to "settle" when generating the display. If you
> execute a sound command the display would flicker and the
> text would be ultra sharp for the duration of the command then
> return to the stable but washed out color artifacted display when the
> command finished.  I tried to attenuate the video output of the coco
> thinking that maybe it was overdriving  the converter, but the result was
> that it would stay in the flickering condition all the time.
>      But if you delete line 10 in the above code and just set the white
> forground and black backround, the converter display had the
> same performance of the CM-8.   There was only the slightest
> artifacting from the converter, almost imperceptable.  You can
> adjust the converters programmable features  to minimize this. With
> any color combination, this converter's composite video performance
> is outstanding to put it mildly.  I guess the conversion process of this
> device depends on ,in some way, the color burst signal for stability.
>
>     All this is good but it does not justify the cost of the XRGB
converter.
> Now it was time to move on to the RGB input.  The manuall called it the
> "game-in" input.   The manual included the pinouts labeled in
> english (thank god ! ).  The connector plugged into the box and
> was terminated with 5 RCA audio style female connectors.  Two
> were actually for left and right stereo audio.  The other three were
> for the three video signals and logically colored according to the signal,
> Red, Green, and Blue.  This is were things get strange.  Remember,
> I'm feeling my way around in the dark with the language barrier.   I
> noticed there wasn't any input for the horizontal or vertical synch
> signals.  It occured to me that maybe they would be combined
> on the green input or something like that.  (I had to go back to
> school about the varies video standards to make sure I wasn't
> missing something).  So I hooked up the signal lines with an opened
> ended cable I keep for the coco for experiments like this and tried
> various configurations with no luck.  I could see the display was
> correct but there was no signal synch occurring.  Just the rolling
> display.  I took another look at the diagram and it showed the synch
> input on a certain pin on the connector but there was no connection
> to it for that pin!  So I decided to disassemble the connector.  This
> turned out to be easy.  A plastic nut that screwed onto the connector
> held it together.  Once removed, it came apart into two pieces revealing
> the solder lugs inside the connector.  I don't know if it was some kind
> of design error or what but the pin that, according to the diaghram,
> was supposed to carry the synch signals wasn't hooked up to
> anything!!
>      To make a long story short, I soldered a wire to that pin and
> brought it out from the connector.  After some scope time and
> a few educated guesses, I determined that the synch signals
> from the coco needed to be hooked up to a nor gate (74LS02) and
> the output of that connected to the newly installed wire.  Upon
> powering up the converter and the coco,  I saw what I had been
> hoping for,  an SVGA image of the coco screen.  It looked every
> bit as good as the screen of an emulator on a modern machine.
> All color combinations and modes where sharp and clear (including
> the color burst off - monochrome mode described above).  I may
> get in contact with the manufactures to see what the deal is
> with the missing input.  It could be that that input is rarely used over
> there and they are unaware of the flaw.
>
>      So this device works extremely well with the coco.  The only
> problems are the cable hack and the high price.  You should
> know that this is an extremely well built and feature packed
> converter.  You can program almost every  aspect of its
> operation.  You can adjust its scanning behavior to match
> it to almost any monitor.  You can control the gain of the
> red, blue and green signals independently of each other. Heck,
> there are even adjustments for stuff I know nothing about. (what
> the heck is "gamma" anyway?).  This converter can sync to
> either 31khz or 47khz.  Could the latter one be for large LCD screens?
> It has the composite video, RGB, S-video and another input I
> don't recognize right off hand.  It even routes audio to your
> PC's speackers.  And It all can be controlled with a remote with
> the size and dimensions of a credit card.
>
>      If any one decides to get this converter,  I can provide details on
> the cable hack.   It was hard to find but easy to do.  I'll do the mod
> for free if not to many people want it, just send me the cable.
>
>      This device is not the ideal solution for the coco.  We need a
> box that simply connects to the coco without all the unnessacary
> bells and whistles at about 1/3 the price.   But this devices does do
> exactly what I think everybody is looking for.
>
>
> Vital statistics:      Manufacturer ----   Pacific Game Technology Ltd.
>                                                        93 Kwai Fuk Road
>                                                        Broadway Centre,
Unit
> B, 17/F
>                                                        Kwai Chung, NT
>                                                        Hong Kong
>
>                              Price + shipping - 209.00
>
>                               email ---------------- www.lik-sang.com
>
> Peace,
>
> Roy R Justus
> rjrtty at aol.com
>
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