Date   : Sun, 07 Feb 1999 20:31:18 +0100
From   : Peter Janssen <pjanssen@...>
Subject: Re: OS Patch for video output.

The problem is that the top-frequency anywhere in the BBC is about 16 Mhz
(crystal).
Any other frequency in the BBC (2 Mhz for the processor, etc.) is achieved
by dividing
this 16 Mhz. So it is not possible to use anything above 16 Mhz, as is needed
for a VGA-monitor.

Peter Janssen
pjanssen@...

Op zaterdag 6 februari 1999 20:28, heeft Mark Usher [SMTP:marku@...]
geschreven:
> Hi
> 
> anyone ever thought of patching the 6845 to output at
> 31.5 KHz Horiz Freq
> 60Hz Vertical Freq
> 
> instead of
> 
> 15.625khz Horiz Freq
> 50Hz Vert Freq
> 
> thus enabling use with VGA monitors. The US MOS does have output at 60 KHz
> so it should be quite feasible. It's not as if we are changing the screen
> resolution. The only if as far as I can see is if the memory would be fast
> enough.
> 
> Mark
> 
>