Subject: Re: Screen Speed?
To: Peter Siebold <>
From: Chris G. Demetriou <>
List: macbsd-general
Date: 08/11/1994 17:42:51
>    I've just helped a freind set up Linux on his 486 box, and noticed that 
>the screen redraws are awfully fast.  Is the 486's video that much faster 
>than the macs, or is the Linux's kernel optimized for such fast screen 

PC video boards have a built-in 'character' mode, and operations on
characters (drawing, scrolling, etc.) can be made much faster because
of it.

Mac's have no such mode, and thus all drawing operations need to be
done by hand.

just looking at the number of byte moves (read or write from mem to
register) needed (i.e., discounting other code needed to deal with
calculation correct positions on the bitmap display) and assuming 8x10
chars on the mac display (that's a _Rather_ small font), you need a
factor of 10x<D == bit depth of display> operations more, on the mac.

With a larger font size, that factor increases, and the increase
isn't really linear.  e.g. 9x12 would require a factor of 36xD
increase, while an 16x20 font would require a 40xD-times increase.

It's as if you were using the VGA mode of a PC video board to
do the character drawing.  "possible, even useful, but a _lot_