Re: Why not just reproduce the second sight card?

[Alex Freed <alex_news@mirrow.com>]

Mark McDougall wrote:
> And no doubt you are well aware Alex - I mention it for the benefit of 
> others - that there's a few IP cores around for FPGA implementations of 
> micros and arcade games that already do exactly this.

I was not aware of this particular fact but I am well aware of a general 
one - that I'm not the only guy in the world designing digital equipment 
:) Not even the  only one in the Silicon Valley.

Seriously one problem with a generic solution not made specifically for 
an Apple 2 computer is the sampling rate. The best way to capture the 
video data is by using the original video clock. Easy if you have access 
to the bus. Also possible to use a PLL locked to the sync signal, but 
unless you target Apple in particular you will not sample at the correct 
rate and as a result will not get a perfect picture. A box designed for 
an analog NTSC TV signal will likely have a reasonable A/D converter but 
will sample at anything but the correct rate for Apple.

-Alex.