Re: Strange Apple II RGB Monitor ---> Apple III

["Roger Johnstone" <rojaws@es.co.nz>]

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In article <8mq0qi$11hi$1@news.gate.net>, louiss@gate.net    (Louis
Schulman) wrote:

>You are correct about everything except the the last part.  Apple actually
>defined XRGB as analog RGB, even though it consisted of 4 digital outputs.
>These digital outputs could be run through a simple circuit (Apple called it
>a "summing network") which supposedly produced analog RGB.
>
>The AppleColor Monitor 100 has this circuitry built in.  There is a diagram
>on how to build this circuit in the Apple III manual, which will allow the
>use of a "normal" analog RGB monitor.
>
>And, as noted in another post, somewhat coincidentally, an Apple IIGS monitor
>will produce a picture from the XRGB signal, but the colors will be wrong and
>you will only get 8 colors (instead of 16).
>
>Louis
>
>PS If anyone has an AppleColor 100 monitor they want to sell, please let me
>know.

I'm finding all sorts of interesting things browsing through Apple's Tech
Info archive e.g AppleColor Monitor 100: Making it compatible with the Apple
IIGS at <http://til.info.apple.com/tilarchive.nsf/artnum/n262>
Apparently there is a switch inside called 16 color/8 color. Setting it to 8
color allows the monitor to display all IIgs colours. Presumably this
disables the summing network, turning it into an analogue RGB monitor.


Roger Johnstone, Invercargill, New Zealand
http://homepages.ihug.co.nz/~rojaws
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