Re: Console thoughts

Tuukka Toivonen (tuukkat@ees2.oulu.fi)
Thu, 9 Jul 1998 20:00:23 +0300 (EET DST)

> Another interesting thought: Make scrolling on the VGA even faster by
>not copying the screen at all (cards capable of 64KB circular buffer
>only).

Wouldn't it be possible to create circular buffer with this:

3d4h index 18h (r/W): CRTC: Line Compare Register
bit 0-7 Lower 8 bits of the Line Compare. When the Line counter
reaches this value, the display address wraps to 0.
Privides Split Screen facilities.
Bit 8 is found in 3d4h index 7 bit 4.
(VGA Only) Bit 9 is found in 3d4h index 9 bit 6.

(this is from vga.doc)
Works on any EGA/VGA.

(By the way, vga.doc has some nasty errors here and there...
I wouldn't blindly trust to numbers above).

--
| Tuukka Toivonen <tuukkat@ee.oulu.fi>       [PGP public key
| Homepage: http://www.ee.oulu.fi/~tuukkat/       available]
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| Studying information engineering at the University of Oulu
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