In message , Mark Carver
writes
Ian Jackson wrote:

Noted. In principle, does (should) AR auto-switching work with
external inputs, or does it only work with the internal tuner?

Yes, it should, by one of two methods for external (SD) inputs.

1: Control voltage on Scart Pin 8.

5 to 8V 16:9 mode
9.5 to 12V 4:3 mode

http://www.idiots.org.uk/vga_rgb_scart/

2: VBI Line 23 signalling:-

http://www.pembers.freeserve.co.uk/T...nical.html#WSS

Noted. Thanks.
There's some really good stuff on Alan Pemberton's site - TV and
otherwise.
--
Ian