Misc/abrash-black-book
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Change bold code snippets to inline code blocks

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James Gregory 2013-12-31 17:12:29 +11:00
commit 3c76d884ef
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8
30-03.md
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@ -12,14 +12,14 @@ pages: 572-574
#### VGA and EGA Split-Screen Operation Don't Mix {#Heading5}
You must set the **IS\_VGA** equate at the start of Listing 30.1
You must set the `IS_VGA` equate at the start of Listing 30.1
correctly for the adapter the code will run on in order for the program
to perform properly. This equate determines how the upper bits of the
split screen start scan line are set by **SetSplitScreenRow**. If
**IS\_VGA** is 0 (specifying an EGA target), then bit 8 of the split
split screen start scan line are set by `SetSplitScreenRow`. If
`IS_VGA` is 0 (specifying an EGA target), then bit 8 of the split
screen start scan line is set by programming the entire Overflow
register to 1FH; this is hard-wired for the 350-scan-line modes of the
EGA. If **IS\_VGA** is 1 (specifying a VGA target), then bits 8 and 9 of
EGA. If `IS_VGA` is 1 (specifying a VGA target), then bits 8 and 9 of
the split screen start scan line are set by reading the registers they
reside in, changing only the split-screen-related bits, and writing the
modified settings back to their respective registers.