Re: SecondSight & TrueColor

[bazyar@netcom.com (Jawaid Bazyar)]

ntt@cleese.apana.org.au (Jonathan Pratt) writes:

>ummm...

>resolution of 1024 * 768 requires a clock frequency of 66 MHz, whereas the
>1280 * 1024 requires a 135 MHz clock.

  Yes, 1024x768x16.7M would require radically different hardware. It
would require a RAMDAC with 24-bit Input pins (the RAMDAC we're
using has a single 8-bit port, but clocks three bytes in succession
in true color mode - it's real TrueColor, just has a smaller databus
to move the pixel data around). A 24-bit databus DAC would be expensive
as all get-out, and would require 24-bit data busses run around the card.

>I don't know of any hardware that works this fast and takes 24 bit input.
>It seems that they tend to take 4 lots of 8 bit (pseudo TC) and run at
>around 33 MHz.

  Yep. The DAC has to be extremely high performance. We're using an
80MHz DAC, but 1024x768x16.7M would require something like a 200MHz part :-)


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