Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!wuarchive!udel!mmdf
From: BARRETT@owl.ecil.iastate.edu (Marc Barrett)
Newsgroups: comp.sys.amiga
Subject: Amiga project feedback.
Message-ID: <13188@baldrick.udel.EDU>
Date: 7 Mar 90 19:09:44 GMT
Sender: mmdf@udel.EDU
Lines: 36


   I need some feedback on a little project I've been considering for the Amiga.
It is very, very simple electronically, but may come in handy when the ECS
comes out.

   As many of you know, the Amiga uses a 28.5Mhz clock, which is divided by four
by the Agnus chip to produce the 7.12Mhz clock.  The original 28.5Mhz signal is
available onthe RGB port.  Also on the RGB port are a number of lines that are
meant for feeding an external clock signal to the Amiga.  Genlocks use this to
replace the Amiga's clock with their own clock, thus synchronizing the Amiga to
the video input of the genlock.

   What I would like to know is this: should it be possible to use these input
lines to feed in a clock signal to the Amiga that is somewhat higher than normal,
but within range of tolerance of the Amiga's chips?

   The project I am speaking of would replace the 28.5Mhz clock with a 40Mhz
signal.  This signal would be divided by four to produce a 10Mhz base frequency
instead of the normal 7.12Mhz.  This would have the effect of speeding everything
up across the board -- video, audio, everything.  The video in particular would 
have a higher frequency: in interlace mode, the 'jitter' would be occurring at 
43Hz instead of 30Hz, reducing the flicker significantly.

   Of course, the Amiga's video would be totally unuseable on a normal monitor,
but a multisync monitor would be able to sort everything out.  "What's the point?"
you may ask.  "The flicker fixer totally eliminates the flicker."  But, there 
are new interlace modes in the new chipset, and there will likely never be a
flicker fixer to deinterlace these modes, because the cost would be prohibitive.
Thus, this method would be the only way to reduce the flicker in the 640x960
and 1280x400 modes of the ECS.

   I have not had a chance to test my little project yet, as I haven't been able
to afford a multisync monitor.


                                              -MB-