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Date:      Tue, 24 Jul 2001 11:46:34 -0400
From:      Christopher Sean Hilton <chris@vindaloo.com>
To:        freebsd-questions@freebsd.org
Subject:   Help getting raster text mode to 1024x768x4bpp.
Message-ID:  <20010724114633.A3262@andale.vindaloo.com>

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I've been wondering why syscons raster graphics mode does not support 1024 
by 768 mode and I appear to have found the answer in this comment from 
/sys/dev/syscons/scvidctl.c:

    /*
     * set_pixel_mode() currently does not support video modes whose
     * memory size is larger than 64K. Because such modes require
     * bank switching to access the entire screen. XXX
     */

So the reason that 1024x768 is not supported for raster text is because it 
requires a 96k buffer and bank switching. 

It's been since the late 1980's since I've played around with EGA/VGA video 
hardware. 

Does anyone know what is required to bank switch a VGA card? 

Is this operation different for each VGA card by type?

-- 
Chris Hilton                                 chilton-at-vindaloo-dot-com
------------------------------------------------------------------------
                "All I was doing was trying to get home from work!"
                                                 -- Rosa Parks

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