Re: Apple 'Monitor 100' works on GS

["Ralph Wade Phillips" <ralphp@gcstation.net>]

Hi, Mitchell!

Mitchell Spector <spec@vax2.concordia.ca> wrote in article
<20SEP199603020059@vax2.concordia.ca>...
>     This is rather interesting. A local person, having come across a pair
> of Apple IIgs's and RGB monitors, asked for the pinouts to GS's RGB port
> (seeing that he lacked a cable to connect the monitor and wanted to build
> his own). I assumed he must have received an AppleColor RGB display, but
> after connecting things up, he reported the screen worked fine _but_
colors 
> weren't matching up. I asked for some details on the RGB monitor; he told

> me it was an Apple model 'A9M0308', beige colored case and pointed out it
> had a motorized tilt screen. If I'm not mistaken, this is the Monitor
100.
> A *digital* RGB display for the Apple III and IIe (with RGB adapter
card).

	... and the //c, again with the appropriate adapter.  Yep, remember them
well.  COmplete with the "Stripamatic(tm)" gear drive for the tilt screen
...  While I was working at Shreve, it was amazing how many we got in that
the motor's gear train was stripped out.  Sigh.

> 
>     A few years ago, I managed to do the reverse. I plugged an analog RGB
> (AppleColor RGB) from a IIgs, into an Apple III. The results were
similar,
> a perfectly viewable image but with color information not matching up.
> How is it an analog and digital RGB screens can be interchangable? Do
these
> monitors have some sort of alternate mode, or the Apple III and IIgs
> themselves have some way of sending out different video signals.

	Neither.  See, on a DIGITAL signal, either the voltage is there, or it's
not.  On an ANALOG signal, it's continuously variable (ya, I know you know
this.)  Now, if you drive the ANALOG FULL-ON, and FULL-OFF only, what do
you have? <B-)  ANS:  You have an 8-color RGB display, with all the three
primaries either fully saturated, or missing.

	For the radio buffs, it's the same way that my car's FM radio can pick up
the Channel 6 AM audio track - it's using a slighhtly different view of the
signal than what's expected of it!

> 
> Mitchell Spector
> spec@vax2.concordia.ca
>

	RwP