🚀 go-pugleaf

In article <1992Aug4.222047.57853@cc.usu.edu> sl8nl@cc.usu.edu writes:
> I'm curious.  What are the speed differences between ModeY and 13h?  In
> my tests, 13h has always come out on top many times over (even copying
> 4 bytes at a time in VGA RAM).  Why is this?  As offered to me by a friend,
> the VGA card is on an 8 mhz bus...so graphics transfers are only at 8mhz.
> If this is the case, the ratio between ModeY and 13h should be fairly
> close.  This is not happening, though.  Can anyone offer a valid explanation
> of why this is?  ModeY offers some very valuable techniques (panning,

	I tested the speed of 320x240x256 mode X and normal mode 13 by
	a simple C program which symply did 10000 byte long memset()
	to screen 10000 times. (486/33, 11MHz bus, Trident 8900 card)
	I did not test moves within the display memory.

	The execution times: almost identical! (note: it did not
	matter whether write was enabled to one or all planes in Mode
	X, the time was the same => ModeX does indeed have four times
	faster performance, if you can update all planes with single
	access).

	I was surprised since usually Trident's planar (16 color) modes
	are much slower than 256 color modes with similar resolutions
	in raw access speeds (according to VIDSPEED 3.0).


--
/*-- Jari.Karjala@hut.fi -- The World is Just a Huge Fractal --*/
float o=0.075,h=1.5,T,r,O,l,I;int _,L=80,s=3200;main(){for(;s%L||
(h-=o,T= -2),s;4 -(r=O*O)<(l=I*I)|++ _==L&&write(1,(--s%L?_<L?--_
%6:6:7)+"World! \n",1)&&(O=I=l=_=r=0,T+=o /2))O=I*2*O+h,I=l+T-r;}