KA10: 340 CRT background color

[larsbrinkhoff]

Here's my photo of a 340 CRT. Maybe change the simulation background color to match?

CC @philbudne

[philbudne]

1. The color of the surface of the tube depends on room lighting, and/or any filter placed in front of the tube.

2. The same tube may have been used in the Type 30 display, so this isn't strictly PDP-10/340 related, and discussion belongs "upstream"

3. I find it hard to believe that this is the LEAST realistic part of the display simulation...

   I've long wondered if:

   high intensity points "bloom" to appear larger than low intensity points... whether this could be simulated by intensifying neighboring display points, and more recently have wondered whether 4K displays (with 3840?×?2160 pixels) might be able and whether current display libraries might offer any portable abstractions to make aging easier...

   The dynamic range of the real tubes was greater than modern displays, and whether anything can be done to better approximate that.

4. In many ways SimH gives an idealized user experience: Console devices were often Model 33 Teletypes, yet the default (AFAIK) is not to display only upper case, at 10 CPS, with the attendant noise, heat and smell (not to mention the effort needed to press any key).

   Likewise (again AFAIK), CPU execution, and disk/tape access speeds aren't as slow as real hardware.

   If/when SimH defaults to reproducing those aspects of the user experience, I think the default display surface color is a salient question (tho again, it depends on the room lighting).

   Until then, my preference is to default to black background, and perhaps have a SET command to allow it to be altered.

5. Finally I started with Doug Jones' VC8E simulation, but never "returned the favor" of adding VC8E support to SimH.

   Doug documents the interface here: http://homepage.divms.uiowa.edu/~jones/pdp8/man/vc8e.html

[rcornwell]

I agree, also these will appear much darker when the monitor is turned on.

What is your thoughts on adding a Triple III display for Waits. I have the basics done, just have not hooked it into the display.

[philbudne]

... what is your thoughts on adding a Triple III display for Waits.>

I know nothing about it, but http://xahlee.info/kbd/sail_keyboard.html says it was a vector display, so the xy display code should be able to support it. For short persistence phosphor displays it's massive overkill!

https://stacks.stanford.edu/file/druid:hb976hq8639/uuomanual.pdf (p.194)

Seems to suggest the display processor could drive 6 displays...

Something I wondered when I was doing the "glass tty" support for the Bell Labs "Graphics II" processor for the PDP-7 was whether one could do vector graphics in a browser window (perhaps a websocket connection to transfer display lists, and rendering code in the browser), and be able to render the button box and push buttons. And from there, perhaps support front pannel lights and switches.... Mark P. was unreceptive (to say the least)...

The Data Disc Display looks fun too!

I'm intrigued by https://www.saildart.org/j5/ the "L5" display has the text

"Test Pattern for SVG based III vector graphics terminal"

[larsbrinkhoff]

Regarding point 3, certainly this isn't the most pressing of all visual improvements that could be done. BUT, it's very easy to change. Low hanging fruit.

I do think there are blooming effects. I also think using a GPU shader language would be a good fit for this.

About point 4, I have long maintained that it would be great to have a realistic teletype simulation. I'm thinking physical model. Heat and smell may be difficult.

I don't know about tape speed, I think Rich made it not too far off.... ;-)

[philbudne]

I randomly learned about HDR 4K video today: ie; 30bpp and 36bpp (vs. the 24bpp we've used for decades). So there's display hardware capable of extended dynamic range! Now support for "DeepColor" in the entire software stack (sim_vid/SDL/window system) is another matter! And if the increase in dynamic range makes it blatently obvious that the aging system has a small number of color gradations, more fun will ensue!

Looking at SDL docs I see SDL_SetPalette -- "Sets the colors in the palette of an 8-bit surface" ... Even 15+ years ago when I started on the XY simulator, I thought color maps had gone the way of the Dodo! Playing color map games (or simply expressing the points on the screen as a small integer aged intensity value) would simplify life. EXCEPT if you want to implement the rare tri-color 340-like display at AI!

Regarding using hardware shaders: Can it be done portably?

Can we agree that one person's "low hanging fruit" could be viewed as gratuitous self gratification by another?

You might get more respect if you came up with code that used the in-screen webcam to determine ambient lighting, and color the background appropriately, but I hope we can agree that it's overkill?! [And I'll still leave my webcam closed (or taped over)!]

Personally, I wretch when I see vector scope simulations with a background color other than black.

[larsbrinkhoff]

I don't do a lot of shader programming, but I have a feeling they have become less portable:

• Windows: HLSL
• Mac and iOS: Metal
• OpenGL: GLSL
• Maybe some subset for GLES
• Playstation 4: PLSL

[larsbrinkhoff]

I'll close this for now. Maybe I'll revisit this if I (or someone else) does a 340 CRT simulation in a shading language.