[Coco] other use for fpga rgb converter

[Luis Antoniosi (CoCoDemus)]

Hi,

Sorry I don't have a IIgs. But it should work.

I'm finishing the board in eagle to be used with the Altera DE0-Nano. It
will include a RCA for the composite video, a coco3 rgb connector and a
generic RGB IN for CSync in an VGA connector. So if your computer has
separate hsync/vsync you should use the COCO3 port, if it has CSync you use
the RGB IN. And the RCA for Apple ii.

I won't be able to use cheap altera boards from ebay because they don't
have a 16-bit SDRAM.

I am very limited on the choice of alteras, it must be Altera Cyclone IV. I
tried compiling for Altera II or III but it was a no-go for the PLL. Cannot
change the PLL speed. So I must stick the the cyclone IV. The cheapest
cyclone IV on ebay costs around 30 dollars. Adding a SDRAM would increase
the price to 10 dollars (plus the work soldering these small legs).

For 79 you buy an DE0 Nano development. Also it has way more quality. Also
my PCB won't have any SMD so it can be assembled by any one with a cheap
soldering iron.

And honestly I don't want to expend money buying a board that would may not
work, doing more prototypes, etc. I have already spent too much money on
retro computing so now I'm very low profile.

The problem with my board is that switching from one computer to another
you need to fine tune the variable resistors. So it's not a plug and play
solution, you should keep it for one computer.

I would need a help for any engineer with video expertise, how do I
normalize different video voltages ?

Should I use transistors ?












Luis Felipe Antoniosi



On Tue, Oct 28, 2014 at 7:22 AM, Steven Hirsch <snhirsch at gmail.com> wrote:

> On Mon, 27 Oct 2014, Luis Antoniosi (CoCoDemus) wrote:
>
>  It can be used as a monochrome monitor:
>>
>> https://www.youtube.com/watch?v=fXNcDfETNFw
>>
>> But no way I can get colors from composite video. Is far to way too
>> complex
>> and requires the PLL to be locked to the color burst, what is not possible
>> only in FPGA.
>>
>
> I. Want. One.
>
> I've been struggling to find such an adapter for Apple //e and yours is
> the best job I've ever seen at displaying 80-column text on a VGA monitor.
>
> Do you have a 2gs?  I'd love to see how well the Coco3 RGB adapter does
> with it.
>
> In all seriousness, when do you expect to be at a point where you will
> either produce some of these or release the design?
>
> Your work is fast approaching the "Holy Grail" for folks like me with too
> many Olde Computers and a collection of aging CRT monitors that they'd love
> to be rid of.
>
> Steve
>
>
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