[Coco] GBS-8200 RGB to VGA

[George Ramsower]

  I could have used that many years ago when I was attempting to build a 
line 21 decoder. I'll even bet it was available then but, I didn't know 
about it.
  For the GBS8200, it isn't necessary. The sync is already available 
from the RGB port on the Coco but, it's the wrong polarity. A simple 
7402 is all that is needed.
George R.

On 9/2/2015 8:52 PM, Barry Nelson wrote:
> You could try using the chip below. It extracts just the sync signal 
> from a composite video line.
>
> http://www.ti.com/lit/ds/symlink/lm1881.pdf
>
>   * *George Ramsower*georgera at gvtc.com
>     <mailto:coco%40maltedmedia.com?Subject=Re%3A%20%5BCoco%5D%20GBS-8200%20RGB%20to%20VGA&In-Reply-To=%3C55E7A496.9070001%40gvtc.com%3E>
>   * /Wed Sep 2 21:38:30 EDT 2015/
>   * I wired it almost exactly as each wire is designated except for the
>   * Horizontal line. I cheated and used the video output from the coco to
>   * steal a proper H sync from. However, in OS9, I had to use "Montype
>     M" to
>   * turn off the color burst because it was messing with the sync in
>     the 80
>   * column mode. 32 and 40 were fine. When I feel like it, I'll put a
>     proper
>   * 7402 chip in line with the H sync line from the coco to invert that
>   * signal. Gene Heskett thinks he may have used a 7406 which does the
>     same
>   * thing but for more power on the output.
>   * George R.
>
>