[Coco] SVGA monitor

[Mark McDougall]

theother_bob wrote:

> It's the AL-250 chip. Look up the datasheet. It's not just a
> line-doubler, it handles the PAL to VGA conversion just like it handles
> the RGB to VGA.

Thanks for the link. But the way I read it, it _is_ just a scan doubler, and 
does _not_ do frame-rate conversion. Page 12 clearly indicates output timing 
for a PAL input signal is 50Hz vertical refresh.

Frame-rate conversion requires a triple-frame buffer, which in turn requires 
quite a decent amount of (fast/dual-port) memory.

FWIW, the reason I am so interested is that my colleague and I are currently 
designing a video converter box aimed at retro enthusiasts with a wide 
collection of 8/16-bit micros. The idea is that it will accept _any_ video 
input and produce VGA/DVI output, with frame-rate conversion, user-defined 
clipping and up-scale conversion.

Only trouble is - it will be _expensive_, perhaps not even commercially 
viable. But since we have 75% of the design in an existing product, it's not 
a lot of (extra) work and we'll at least do a small prototype run for 
ourselves... and then we can gauge interest of anyone as crazy as we are! ;)

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"