Date   : Tue, 28 Nov 2006 20:48:04 +0000 (GMT)
From   : info@... (Sprow)
Subject: Running on an NTSC display?

In article <456C57AF.8070809@...>,
   Jules Richardson <julesrichardsonuk@...> wrote:

> Out of interest, what changes were done for US-spec BBC micros in order 
> for them to operate with an NTSC TV rather than a PAL one? Was it just a 
> case of changing the modulator to something else, or was something more 
> drastic done?

For all, you'll need a different MOS so the 6845 CRTC gets poked to generate
60 fields a second and appropriately reduced line count.

For RGB, I can't think of any hardware changes.
For composite, the colour crystal needs changing from 4*4.43 to 4*3.59.
For UHF, as composite plus the change in channel.

> PSU is less of an issue as I've got a whole range of options there

Interestingly there is provision for a 110V option on the PSU board, but
I've never dared cut the track/add link as I suspect the transformer or some
feedback resistors might also need changing,
Sprow.