VOGONS


First post, by witchspace

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Just out of curiosity I wonder if any hardware ever existed that natively could set a text mode with more than 16 colors.
In the 90's there were tons of different, incompatible SVGA cards so maybe one of the vendors would have had this crazy idea.
Or some of the more high end VT terminals maybe?

I'm pretty sure the answer is "no", but I've not been able to find any discussion on this anywhere on the internet. From the looks of it, 256-color support (first 88-color) started with xterm which was always targeted for graphics mode.

Reply 1 of 6, by Ampera

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Probably not, The thing is once more colours were a thing, text mode didn't have a reason to exist except for backwards compatibility.

Reply 2 of 6, by mrau

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according to this https://en.wikipedia.org/wiki/VGA-compatible_text_mode we already use an entire byte for the characters attributes, which means an "upgrade" is unlikely;theoretically now that text modes are more or less "cheated" and actually a real framebuffer is used, the amount of colors might be higher;

Reply 3 of 6, by Zup

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I guess not.

Text format in memory was character-attributes-character-attributes... if you wanted more colours for foreground and background colors, you'll need more bits so you'll end breaking up that "standard".

Note that graphic modes usually could display text via BIOS calls (int 10 allows up to 256 colors for the character), and that any VGA can redefine text colours. If you use int 10, it still will be a graphic mode (no character+attribute adressing). If you redefine the VGA palette, you'll end up still with 16 colours, but not the usual ones.

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Reply 4 of 6, by witchspace

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Thanks for the insights.

mrau wrote:

according to this https://en.wikipedia.org/wiki/VGA-compatible_text_mode we already use an entire byte for the characters attributes, which means an "upgrade" is unlikely;theoretically now that text modes are more or less "cheated" and actually a real framebuffer is used, the amount of colors might be higher;

Well they could theoretically have done some tricks to remain VGA compatible, for example have multiple planes with two bytes per character, one the normal text memory at 0xb8000, another with "extended attributes" which would (say) have the upper four bits for the foreground and background and maybe an upper byte for the text (to support >256 character sets).

There's nothing technical that prevented anyone from doing this. But yes, as Ampera says text mode was mostly compatibility concern at that point so it was not given much thought.

Reply 5 of 6, by Scali

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Not directly, but you can reprogram the palette as often as you like during a frame, so raster effects are possible, allowing you to effectively have way more than 16 colours on screen at a time.
Here's an intro that does some clever effects like that: https://www.facebook.com/jim.leonard/videos/1 … 55026219968307/

http://scalibq.wordpress.com/just-keeping-it- … ro-programming/

Reply 6 of 6, by witchspace

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Ah yes, palette effects allow for some really impressive things.

The drawback is that they use a lot of CPU, usually some kind of busy-looping, so the greatest advantage of text mode - rendering very fast with minimal CPU and I/O overhead - goes away.