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Remove heading ids, let pandoc generate them

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James Gregory 2014-01-06 22:51:26 +11:00
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18
chapter-27.md
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@ -11,9 +11,9 @@ pages: 499-521
---
## Chapter 27\
Yet Another VGA Write Mode {#Heading1}
Yet Another VGA Write Mode
### Write Mode 2, Chunky Bitmaps,and Text-Graphics Coexistence {#Heading2}
### Write Mode 2, Chunky Bitmaps,and Text-Graphics Coexistence
In the last chapter, we learned about the markedly peculiar write mode 3
of the VGA, after having spent three chapters learning the ins and outs
@ -31,7 +31,7 @@ ever imagine.
Let's start with the easy stuff, write mode 2, and save the read modes
for the next chapter.
### Write Mode 2 and Set/Reset {#Heading3}
### Write Mode 2 and Set/Reset
Remember how set/reset works? Good, because that's pretty much how write
mode 2 works. (You *don't* remember? Well, I'll provide a brief
@ -68,7 +68,7 @@ nonetheless, I suspect that some additional explanation of an admittedly
non-obvious mode wouldn't hurt. Let's follow the CPU byte through the
VGA in write mode 2, step by step.
#### A Byte's Progress in Write Mode 2 {#Heading4}
#### A Byte's Progress in Write Mode 2
Figure 27.1 shows the write mode 2 data path. The CPU byte comes into
the VGA and is split into four separate bits, one for each plane. Bits
@ -130,7 +130,7 @@ on the VGA is to read the Graphics Mode register, mask off bits 1 and 0,
OR in 00000010b (02H), and write the result back to the Graphics Mode
register, thereby leaving the other bits in the register undisturbed.
#### Copying Chunky Bitmaps to VGA Memory Using Write Mode 2 {#Heading5}
#### Copying Chunky Bitmaps to VGA Memory Using Write Mode 2
Let's take a look at two examples of write mode 2 in action. Listing
27.1 presents a program that uses write mode 2 to copy a graphics image
@ -406,7 +406,7 @@ to illustrate the mechanics of write mode 2.
> time, nasty transient color effects can occur as one plane becomes
> visibly changed before other planes have been modified.
#### Drawing Color-Patterned Lines Using Write Mode 2 {#Heading6}
#### Drawing Color-Patterned Lines Using Write Mode 2
A more serviceable use of write mode 2 is shown in the program presented
in Listing 27.2. The program draws multicolored horizontal, vertical,
@ -764,7 +764,7 @@ Code ends
end Start
```
### When to Use Write Mode 2 and When to Use Set/Reset {#Heading7}
### When to Use Write Mode 2 and When to Use Set/Reset
As indicated earlier, write mode 2 and set/reset are functionally
interchangeable. Write mode 2 lends itself to more efficient
@ -785,7 +785,7 @@ the value written to some planes to a fixed value while allowing the CPU
byte to modify other planes. This is the mode of operation when
set/reset is enabled for some but not all planes.
### Mode 13H—320x200 with 256 Colors {#Heading8}
### Mode 13H—320x200 with 256 Colors
I'm going to take a minute—and I do mean a minute—to discuss the
programming model for mode 13H, the VGA's 320x200 256-color mode.
@ -803,7 +803,7 @@ program, especially given that some of the listings later in this book,
such as the antialiasing code in Chapter F on the companion CD-ROM, use
mode 13H.
### Flipping Pages from Text to Graphics and Back {#Heading9}
### Flipping Pages from Text to Graphics and Back
A while back, I got an interesting letter from Phil Coleman, of La
Jolla, who wrote: