Re: Can I use a US motherboard in my European Apple IIe?

["Knut" <kr-lund@nogarbage.online.no>]

Matt wrote:
...
> FWIW, I actually convert the output of my RGB card to analog using a
> resistor network (of the same design as the the one inside the
> AppleColor Monitor 100) and then to svideo for display on a television.
> This way, I can have decent RGB output and traditional composite output
> by switching inputs on the TV.

I was wondering about doing the same, actually do scart RGB for a modern TV. 
I have actually managed to use the CGA IBM 5153 monitor as a replacement for 
AppleColor 100 (which I think is impossible to get). I will document how it 
was done with diagram and photos on my site sometime soon, I will announce 
here.

This particular CGA monitor actually needs both vsync and hsync and it needs 
a 60Hz signal. I was wrong, it really needs vsync. I replaced my european 
IIe motherboard with a US one i.e. NTSC (had to extend the speaker lead and 
make a longer keyboard cable, thanks Marcus). The CGA needs positive pulses 
on the sync signals so I create vsync with an LM1881 and invert both this 
vsync and the composite sync which then works for hsync.

I also tried to use some analog monitors that was available doing the 
summing network as described by Marco Orlandi in his document on the net. 
Matt, is this similar to yours? Composite output how do you do that? Could 
you describe your circuit or do you use a ready made device?

(I have a colour kit for my Video Genie that does that but it is a lot of 
components, analog stuff, but then maybe PAL composite color is more 
difficult that NTSC composite color.)

I think for scart RGB I need only the summing network for "XRGB" to analog 
RGB, the sync should be composite and negative and 75ohm so it is correct as 
it is.

BTW I'm also wondering a bit on the colors they change with this RGB output 
being more normal (comparing with other computers). I have now seen the NTSC 
colors  which BTW is quite a bit stronger than the PAL ones. How are the IIc 
and IIgs RGB, do they represent the colors like the original II or like my 
IIe RGB card?

Knut
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