Long story short. (I've posted on several forums, reddit, and Facebook and no one has gave me a solution, but only likes, and history lessons)
I'd like to use my super rare Applecolor 100 monitor with my raspberry pi 5.
I thought the applecolor 100 was an analog RGB, but turns out it's an TTL.
I tried using a GBS-8100 vga converter to match the 15khz speed, and tried directly plugged. Not wanting to display either way.
I was going to purchase a VGA666 HAT, but now I know the monitor is a TTL idk where to go about this.
So which brings me to my question. How can I make my pi to work with this beautiful monitor?
The AppleColor 100 monitor uses digital (TTL) RGBI inputs, at 15.7 kHz horizontal scan rate. This is very close to IBM's CGA monitor, but the sync signal is different: IBM used separate positive-going sync, Apple used combined negative-going sync. So to convert from AppleColor 100 to CGA (or the reverse) requires one or two logic chips to invert the sync signals.
However, I don't know of any converter from HDMI (like is output by the RPi) and either digital CGA or general RGBI. Most converters are designed for analog RGB displays, like you would find in an arcade cabinet. On the RPi forum here, a poster complains, "None of the VGA to CGA converters I can find out there actually produce RGBI."
Most people want to go the other way, bridging the CGA or RGBI output of their vintage computer to a modern LCD screen, for which there are several converters available. Sad to say, the science and lore of CRT displays is vanishing as we speak, and the enthusiasts who still use them are a tiny market, which would be very difficult to profit from.
In principle, it is possible to convert to digital RGBI, but it would require some bespoke engineering, since nothing off-the-shelf has been built for that. If there are converters based on configurable logic elements (FPGA or CPLD), then adapting one of them to RGBI would be possible.
Could this be accomplished with a pair of 74LS04 hex inverters? You could breadboard that up in 10 minutes.
Seems too simple.