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Convert notes into blockquotes

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James Gregory 2013-12-31 11:06:31 +11:00
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04-10.md
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@ -10,9 +10,14 @@ chapter: '04'
pages: 106-109
---
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![](images/i.jpg) *A line-drawing subroutine, which executes perhaps a dozen instructions for each display memory access, generally loses less performance to the display adapter cycle-eater than does a block-copy or scrolling subroutine that uses **REP MOVS** instructions. Scaled and three-dimensional graphics, which spend a great deal of time performing calculations (often using very slow floating-point arithmetic), tend to suffer less.*
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> ![](images/i.jpg)
> A line-drawing subroutine, which executes perhaps a dozen instructions
> for each display memory access, generally loses less performance to the
> display adapter cycle-eater than does a block-copy or scrolling
> subroutine that uses **REP MOVS** instructions. Scaled and
> three-dimensional graphics, which spend a great deal of time performing
> calculations (often using very slow floating-point arithmetic), tend to
> suffer less.
In addition, code that accesses display memory infrequently tends to
suffer only about half of the maximum display memory wait states,
@ -48,9 +53,10 @@ and alter the rest, and write the byte back to display memory. Half as
many display memory accesses means half as many display memory wait
states.
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![](images/i.jpg) *Moreover, 486s and Pentiums, as well as recent Super VGAs, employ write-caching schemes that make display memory writes considerably faster than display memory reads.*
------------------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> ![](images/i.jpg)
> Moreover, 486s and Pentiums, as well as recent Super VGAs, employ
> write-caching schemes that make display memory writes considerably
> faster than display memory reads.
Along the same line, the display adapter cycle-eater makes the popular
exclusive-OR animation technique, which requires paired reads and writes