[Coco] other use for fpga rgb converter

[Steven Hirsch]

On Tue, 28 Oct 2014, Luis Antoniosi (CoCoDemus) wrote:

> 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.

Doesn't bother me at all.  If I add up the money and time I've expended in 
a fruitless effort at getting clean video conversion I could buy a dozen 
DE0 boards - maybe more.

> 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.

I would like to put my money where my mouth is and contribute towards your 
development costs.  Anyone else want to join me in stepping up?

If you will allow me to do this, please contact me privately with a PayPal 
address?

> 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 plan to buy several if the results are anything like what you've showed 
in your YouTube videos.

Once boards are available, I plan to talk at length about this on 
comp.sys.apple2.  There's an avid community of A2 users facing the same 
challenges as I am:  dying CRT monitors and/or insufficent space to set 
them up.

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

Gene Heskett has forgotten more about video than I could hope to know in 
two lifetimes.

> Should I use transistors ?

On the inputs?  Probably a question for folks smarter than I (Gene?)

Steve


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