1 Sep
2011
1 Sep
'11
4:08 p.m.
On Thu, 1 Sep 2011 23:01:08 +0100 (BST), ard at p850ug1.demon.co.uk (Tony
Duell) wrote:
Right - thinking back, it was only the colour encoding side of things that
was a bit strange. I don't know much about NTSC or the way the Apple II
does it. Might do some research there in that case, though I think that
side of things is all fine now.
I should try
to figure out exactly how the video encoder works in these
things. I hear the design is a bit... creative. Maybe there's a decent
description on the web somewhere.
Actually, the video timing chain looks quite
conventional. The cut/jumperpads appear to change the numebr of
lines per frame only.
In other words, in the '60Hz' position, you get 525
line 60Hz video. If you changthe padsettings, you'll get something
_close_ to 625 line 50Hz video, but with the US horizotnal frequency
(15750 Hz) not the European one ((15625 Hz). Most monitors will hve no
problem wit htat at all, of course, but some things might.
Right, that explains quite a lot.
What is the current setting of the pads?
The pads have all been changed over to 50Hz, and the crystal's been
replaced. Sounds like the complete conversion's been done. I'll try running
it on a the 14.318MHz crystal; from what you say above, I doubt I'll have
an issue with that.
Cheers,
Mike