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James Gregory 2013-12-31 11:06:31 +11:00
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@ -36,11 +36,12 @@ memory tends not to be as bad as VGA I/O, but lord knows it isn't
Table: Table 45.1 Results of I/O performance tests run under the Phar
Lap386|DOS-Extender.
* * * * *
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![](images/i.jpg) ***OUT**s, in general, are lousy on the 486 (and to think they only took three cycles on the 286!). **OUT**s to VGAs are particularly lousy. Display memory performance is pretty poor, especially for reads. The conclusions are obvious, I would hope. Structure your graphics code, and, in general, all 486 code, to avoid **OUT**s.*
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> ![](images/i.jpg)
> **OUT**s, in general, are lousy on the 486 (and to think they only took
> three cycles on the 286!). **OUT**s to VGAs are particularly lousy.
> Display memory performance is pretty poor, especially for reads. The
> conclusions are obvious, I would hope. Structure your graphics code,
> and, in general, all 486 code, to avoid **OUT**s.
For graphics, this especially means using write mode 3 rather than the
bit-mask register. When you must use the bit mask, arrange drawing so