VOGONS


First post, by Rikintosh

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Why 320x400 instead of 640x400? I know the obvious answer would be to save some sort of memory.

But I wanted to fundamentally understand why that is, and why a 640x230 image doesn't work?

Edit: I found this: "Just like the bootsplash screens in earlier versions of Windows, there was a hard but poorly documented limit on how large the compressed file could be, because of the very limited memory available during the boot process (the very reason that RLE was used in the first place - a plain BMP would have been 125kb and thus entirely too large; the default images are around 10 to 70kb each). If the file was too large, it would either simply fail to display or cause the system to crash, which required the user to reboot and drop into DOS mode before the logo had a chance to load, and either delete it or rename it to prevent the system trying to display it again before it could be fixed or replaced. Staying below, and moreover editing an image to bring it below this limit was an imprecise science that mostly required taking advantage of the particular characteristics of RLE, e.g. ensuring there were sufficient areas of the screen with long horizontal runs of the same color, by reducing the dither quality or color reduction mode, shrinking it slightly and adding a black border a few pixels wide all around, etc. Each run allowed a two byte code to represent a strip many pixels wide, and hence blank spaces or areas of flat color compressed very tightly, whereas regions with no repeated colors at all were at best uncompressed, at worst slightly larger than they would otherwise have been."

I'm now looking for a way to load the image in another resolution

Take a look at my blog: http://rikintosh.blogspot.com
My Youtube channel: https://www.youtube.com/channel/UCfRUbxkBmEihBEkIK32Hilg

Reply 1 of 4, by jakethompson1

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Whatever VGA mode the card is in during the splash screen is 320x400 resolution; even if they wanted to support something else, it would have to be downscaled at runtime making it pointless.
By the way, do you know how the animation at the bottom works? iirc it works by reserving a portion of the palette for the colors in its gradient, and rather than moving pixels around, the palette is simply changed to give the appearance of animation.

Reply 2 of 4, by Rikintosh

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jakethompson1 wrote on 2023-06-12, 22:07:

Whatever VGA mode the card is in during the splash screen is 320x400 resolution; even if they wanted to support something else, it would have to be downscaled at runtime making it pointless.
By the way, do you know how the animation at the bottom works? iirc it works by reserving a portion of the palette for the colors in its gradient, and rather than moving pixels around, the palette is simply changed to give the appearance of animation.

Yes, I spent months studying this to develop my own boot screen. I created a 640x400 32 bit color image, and split the windows flag into several different colors, then I reduced the image to 320x400, and used a utility to modify the palette, making all the colors black, and a gray gradient, and set the amount of palette colors to be animated. The result is a glow flickering from right to left during the boot process.

https://www.youtube.com/watch?v=2Qg60Vo6mw0

Take a look at my blog: http://rikintosh.blogspot.com
My Youtube channel: https://www.youtube.com/channel/UCfRUbxkBmEihBEkIK32Hilg

Reply 3 of 4, by bakemono

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At this early stage of the boot process, video card drivers aren't loaded yet. Win9x only requires a VGA card, it doesn't require SVGA and it doesn't have built-in VESA support. So it can only use a screen mode supported by plain VGA. Even though it's not one of the standard BIOS modes, 320x400 should work on any VGA compatible card (there could be some rare exception, but I've never seen it). 640x400 with 256 colors isn't possible on original VGA cards. Bumping it up from 320 to 360 would be possible but less compatible, as there were definitely some laptops that would choke on that.

again another retro game on itch: https://90soft90.itch.io/shmup-salad

Reply 4 of 4, by Harry Potter

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Do I have permission to SPAM about some start-up screens and handling tools I found online and my example start-up screens here?

Joseph Rose, a.k.a. Harry Potter
Working magic in the computer community