game boy kiosk picture generation

how do the original gb kiosks put the game image on the crt screen? how are they generating the gb screen frame as part of the image?

I thought they were Wide Boys, game boy adapters made for the NES.

So it's taking the screen output of a game boy, and converting into video memory for the NES to display.

interesting, i wasn't aware wide boys existed for nes hardware. some good info here:
http://www.chrismcovell.com/wideboy.html

interestingly the kiosk seems to put the game on the gb screen and the monitor at the same time. its hard to see but i think that's what happening in the right hand photo.

I think inside is a WideBoy 3 unit. Here's a pic inside of one, in fact.

I assume they are using monochrome CRTs for those kiosks, but are those CRTs black and white? In other words, is all the "color" coming from that pane of yellow plastic in front of the screen?

Yes, it's a green plastic cover, I hear.

Yep, it just a green overlay over a black and white CRT, I actually have one, it's pretty neat. I do not know exactly how it works, but there is a ribbon cable coming out of the back of the GB, which I assume is splitting the video. There is also an RCA plug going into the headphone jack for the audio.

is the wide boy hardware running through nes/other hardware? or outputting directly to the monitor?

Via a NES. Ccovell covered this in the link you posted earlier.