🚀 go-pugleaf

I may be able to get hold of a big, nay BIG monitor for peanuts if I can
convince the owners that I can make use of it. We believe that it is a CGA
monitor, a Beeb modified to give NTSC style outputs drove it OK, and I have
a suspicion that it may be actually CGA/EGA dual sync as was the style for
PC-ATs once. The inputs are seperate R G B HS VS which are all available
from the video connector on my A4, and I can make a suitable cable. What I
do need to know though is how to make the A4 put out CGA (640 x 200) and EGA
(640 x 352) signals.
The Risc-OS 3 docs describe CGA and EGA style modes, but imply that these
are really VGA modes with blank scan lines above and below so that they look
like CGA and EGA to the computer but VGA to the monitor! These modes will
probably not drive a true CGA monitor, or am I wrong here.

If anyone has some generic mode defining code (Basic, Pascal, C, Ass. all
acceptable), or sufficient technical hints (I have a VIDC data sheet) so
that I may write my own legal (i.e. Riscos can use it) mode, then I will be
ingratiatingly and excrutiatingly grateful. #~Q

Thanks,

Mark.

marks@cs.man.ac.uk aka M.B.STEPHENS@UK.AC.MANCHESTER