[Coco] CoCo 3 to VGA

[Mark Marlette]

At 05:30 PM 5/22/2004 -0400, you wrote:

Thanks for explanation, making more sense.

I thought for sure that Gene Heskett would be on this thread!

:)




>On 22-May-04, at 5:12 PM, Mark Marlette wrote:
>
>>I'm not a video guy so can someone explain to me why there is only four 
>>levels per signal? The CoCo is RGB-A, I don't understand how the CoCo can 
>>only have four levels.
>
>Only 4 levels for each of the red, green and blue signals, since the 
>CoCo's video only supports that much. Two bits per component, for 6 bits 
>total, and 64 colours. So multiply that by the number of pixels per 
>scanline, by the number of scanlines and you have the amount you'd have to 
>store in memory to have a frame of CoCo video stored. Then you could 
>replay it at twice the rate until you get a new CoCo frame in memory.
>
>I'm not sure how many scanlines and such there are, but I'm guessing that 
>for an NTSC CoCo that the video matches an NTSC frame, so 720x486. That's 
>349920 pixels, at 6 bits each, which comes to just over 256K, if the 
>6-bits are packed to make best use of the memory.
>
>Now, assuming that you want to store two frames, the one you're getting, 
>and the one you're sending, you'd need just over 512K memory. Combine that 
>with simple A/D components and such, and you've got a product that I'm 
>sure many here would go gaga over. :)
>
>James
>
>
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