AppleVision CRT stuck in resolution limbo

Question

I'm not sure where best to post this but will start here... A few months ago I brought home an old AppleVision 17" CRT from the office graveyard and started using it with my G5, because its viewable area was a little bigger than that of my NEC MultiSync 70, and I liked how it looked.
Tonight I was trying to change the desktop image and getting frustrated because I couldn't seem to get the portion of the image I wanted to fill the screen no matter how I fiddled with the original in Photoshop. So I started fooling around with the resolution.
Unlike with the MultiSync, the G5 doesn't recognize exactly what monitor this is, identifying it only as "VGA Display." So some of the listed resolutions don't work and the screen goes black if you select those. It's supposed to come back and offer you the chance to revert to the previous setting if you click the mouse or hit return, I forget which, while you're in the black screen, and that has worked before. But this time I did something spastic, I think. It went back to black and all sorts of keystroke combinations failed to bring it back. Forcing power down and restarting (twice) only got it as far as the solid blue, blank screen; then it went black again.
I disconnected it and reconnected the Multisync, which is working fine. I hoped that would serve to reset something, but when I tried reconnecting the AppleVision it still couldn't finish booting up.
So then I connected the AppleVision to my main PM 7600. On the first boot the progress bar stalled at an inch or so, without displaying any icons. But the second time, it finished the boot and everything is displaying normally.
This is all beyond me--I have no idea what happened. Is the display "unstuck" now and likely to work with the G5 again? Should I trash com.apple.systempreferences.plist first? Or is it better (for the sake of the computers and/or the safety of operating these old CRTs) to leave well enough alone, i.e., let the 7600 run the AppleVision and the G5 run the not-so-ancient MultiSync?
PM G5 2.0 DC; two PM 7600s; Mini (at work) Mac OS X (10.4.7) 7600/120: 604e (233 mHz), 128 MB RAM, 2 IHDs, USB, OS 9.1

Answer 1

Kathi,
Glad things started to resolve in your favor. : D
You said "If I try to go to the smaller (?) resolutions, e.g. 1024 x 768, the color depth changes from millions to thousands. On the G5, it was set at 1024 x 768, 60 Hz. "
It is all about math. If you have 640 x 480 pixels on the screen and each pixel has a colour depth of 8, then you need the computational power of 6404808 = 2,457,600 (bits or bytes - I need to check that brain cell) to handle that much data.
A colour depth of 256 is 640480256=78,643,200
A colour depth of 32,768 (or what is referred to as thousands is 64848032,768=10,066,329,600
A colour depth of 16.2 million colours (introduced in 1987 with the Mac II - which also caused panic in the IBM camp that boasted 256 colors at the time) is 640480approx 12,200,000=4,976,640,000,000
(4.97664 × 10 to the 12th)
A color depth of thousands at a resolution of
102476832,768=25 769 803 776
Now jump to millions of colors. That calculates out at 1024768162000000=12740198400000
or 1.274... to the 13th power.
Once you hit an integer with thirteen zeros after it, you need a lot more video ram. I will try and find a website with a good illustration of the video math that happens at 30 frames per second. Forget the math that Excel is doing inside a spreadsheet, that is child's play compared to what video processors are doing thirty frames a second to bring motion images to the screen.
Just something to ponder.
Ji˜m