[Coco] rgb2vga

[Mathieu Chouinard]

Hi,
Will an adaptation of the attached schematic
works for a commodore 128 or do I need to
go with the board modification ?
Also does any one as the cable schematic
for a MSX2+ (Sony HB-F1XDJ) ?
I can probably figure out the cable for
the atari 130xe (with a VBXE installed)


Mathieu

On Tue, Sep 20, 2016 at 11:23 AM, Mathieu Chouinard <chouimat at gmail.com> wrote:
> Hi Ed,
> thanks for the information.
> I managed to score a few nice things on ebay:
> 1 MSX2+, 1 Atari 130 XE, 1 Commodore 128 and 1 Ti-99/4A
> all still in the box ... hours of fun (and probably cursing too)
> at the horizion ...
> Mathieu
>
> On Tue, Sep 20, 2016 at 11:19 AM, Zippster <zippster278 at gmail.com> wrote:
>> Hi Mathieu,
>>
>> R, G, and B are taken in on pins 1,2,3 as usual, composite sync on pin 13.
>>
>> Here’s the routing for the board I did (Luis’s original board has the same circuit).
>> <https://drive.google.com/open?id=0B1sgl615FlGnWmhISkRVZkRjU0k <https://drive.google.com/open?id=0B1sgl615FlGnWmhISkRVZkRjU0k>>
>>
>> As you can see, there’s no separate hsync and vsync on the connector, so for the
>> C128 RGB port, you would probably want to run some patches between the RGBI and
>> analog RGB connectors.  You’ll also need to patch the intensity line (with a voltage divider)
>> to the FPGA IO header as detailed on Luis’s site.
>>
>> An easier approach is probably to have one end of your cable a 10 pin header connection
>> and just use the analog port.
>>
>> A note of caution…  as you probably already know, the C128 will be putting out TTL level
>> signals, so you’ll want a series resistor on the RGB lines (to act as dividers with the already
>> present terminating resistors on the board) in order to drop the voltage to levels that won’t
>> harm the FPGA IO.  Also be sure you’re running with the ground fix on the hsync divider, for the
>> same reason.
>>
>> You may have to adjust the FPGA programming to sync the pixel clock with the one in the C128
>> more closely for the intensity signal to be applied to the video conversion in a stable manner.
>>
>> This issue could be avoided by using some logic and a simple resistor DAC to create pseudo-analog
>> signals from the TTL inputs before sampling.
>>
>> I hope that helps, and good luck.  :)
>>
>>
>> - Ed
>>
>>
>>
>>> On Sep 20, 2016, at 9:17 AM, Mathieu Chouinard <chouimat at gmail.com> wrote:
>>>
>>> On Tue, Sep 20, 2016 at 9:48 AM, Robert Gault <robert.gault at att.net> wrote:
>>>> Mathieu Chouinard wrote:
>>>>>
>>>>> what is the pinout of the rgbin connector?
>>>>> Mathieu
>>>>>
>>>>
>>>>
>>>> 9  7  5  3  1
>>>> .  .  .  .  .
>>>>
>>>> .  .  .  .  .
>>>> 10 8  6  4  2
>>>>
>>>> RGB pins on Coco3
>>> sorry I was talking about the DB15 RGBIN connector.
>>> I'm trying to build a cable for a commodore 128
>>>
>>> --
>>> A te quaeso, sicut in Aeneidos libro quarto Aeneas, elocutus
>>> desiderium erigendi suum obeliscum in templo Venereo Didonis, ab ea
>>> quaesivit, tuae domi an meae?
>>>
>>> --
>>> Coco mailing list
>>> Coco at maltedmedia.com
>>> https://pairlist5.pair.net/mailman/listinfo/coco
>>
>>
>> --
>> Coco mailing list
>> Coco at maltedmedia.com
>> https://pairlist5.pair.net/mailman/listinfo/coco
>
>
>
> --
> A te quaeso, sicut in Aeneidos libro quarto Aeneas, elocutus
> desiderium erigendi suum obeliscum in templo Venereo Didonis, ab ea
> quaesivit, tuae domi an meae?



-- 
A te quaeso, sicut in Aeneidos libro quarto Aeneas, elocutus
desiderium erigendi suum obeliscum in templo Venereo Didonis, ab ea
quaesivit, tuae domi an meae?
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pull2-rgba-xor.gif
Type: image/gif
Size: 20889 bytes
Desc: not available
URL: <https://pairlist5.pair.net/pipermail/coco/attachments/20160925/ba37309a/attachment.gif>