🚀 go-pugleaf

In article <kWHFvXK@quack.sac.ca.us>, mrapple@quack.sac.ca.us (Nick Sayer) writes:
> I've managed to obtain at a rediculously low price
> a motherboard for the grand old video game "Robotron: 2084".
> I know it generates analog R, G, and B signals, and separate TTL
> horizontal and verticle sync outputs. Fine and dandy. Setting aside
> for the moment concerns about losing definition, is there a way
> (I know it won't be easy) to convert this signal into an NTSC
> format? Monochrome will do, by the way.
> 
> If not, all is not lost. I know that the Apple IIgs monitor is an
> Analog RGB monitor, but it needs a composite sync signal. My bright
> idea is to send the TTL H and V sync into the control pins of a pair
> of CD4066 "digital switch" elements, whose inputs attach to
> a pair of pots, and outputs connect together and go to the
> composite sync output. Will this plan work?
> 
> -- 
> Nick Sayer              |    Official Scapegoat for the    | RIP: Mel Blanc
> mrapple@quack.sac.ca.us |      MC68HC11 Mailing List.      |   1908--1989
> N6QQQ                   |    To subscribe, send mail to    |  May he never
> 209-952-5347 (Telebit)  | mc68hc11-request@quack.sac.ca.us |  be silenced.


Well, this will be the third time I tried to reply to this.  If
this is the 3rd time you have seen it, my appologies (sp), but
as far as I can tell it is not getting out.

First of all, I hope you mean board set not board as Robotron is
a four board set, ROM, Input, Sound, and Video/CPU.

Second, a composite sync is already available, just normally not
used.  Check out the schematics that show the connector that has
the horizontal/vertical syncs and you will find an unused pin.
On the schematic for the Video/CPU board you will find that this
is a composite sync output.

If you do want to make a composite sync out of seperate horizontal
and vertical syncs, this is often done by connecting both syncs to
inputs of an exclusive-or gate and the output is used as a composite
sync.  Sometimes some inversions are needed depending on whether
you need active low or active high syncs.

	I hope this helps,
				Rick Schieve
				rls@ihlpb.att.com