Misc/abrash-black-book
Watch
1
0
Fork
You've already forked abrash-black-book
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Retidy, removing align=left from headings and empty paragraphs

Browse source
This commit is contained in:
James Gregory 2013-12-30 15:37:13 +11:00
commit a96a114403
362 changed files with 8472 additions and 5040 deletions
Download patch file Download diff file Expand all files Collapse all files

31
55-04.html
View file

@ -1,5 +1,4 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
@ -19,17 +18,21 @@
<center>
<table border="1">
<tr>
<td><a href="55-03.html">Previous</a></td>
<td>
<a href="55-03.html">Previous</a>
</td>
<td><a href="index.html">Table of Contents</a></td>
<td>
<a href="index.html">Table of Contents</a>
</td>
<td><a href="56-01.html">Next</a></td>
<td>
<a href="56-01.html">Next</a>
</td>
</tr>
</table>
</center>
<p><br /></p>
<p>This is where it gets a little complicated. In write mode 3 (which incidentally is not available on the EGA), each byte value that the CPU writes to the VGA does not get written to display memory. Instead, it turns into the bit mask. (Actually, it&rsquo;s ANDed with the Bit Mask register, and the result becomes the bit mask, but we&rsquo;ll leave the Bit Mask register set to 0xFF, so the CPU value will become the bit mask.) The bit mask selects, on a bit-by-bit basis, between the data in the latches for each plane (the previously loaded background color, in this case) and the foreground color. Where does the foreground color come from, if not from the CPU? From the Set/Reset register, as shown in Figure 55.3. Thus, each byte written by the CPU (font data, presumably) selects foreground or background color for each of eight pixels, all done with a single write to display memory.</p>
<p><a id="Fig3"><img src="images/55-03.jpg" /><br />
@ -212,16 +215,20 @@ DrawTextString endp
end start
</pre>
<p><br /></p>
<center>
<table border="1">
<tr>
<td><a href="55-03.html">Previous</a></td>
<td>
<a href="55-03.html">Previous</a>
</td>
<td><a href="index.html">Table of Contents</a></td>
<td>
<a href="index.html">Table of Contents</a>
</td>
<td><a href="56-01.html">Next</a></td>
<td>
<a href="56-01.html">Next</a>
</td>
</tr>
</table>
</center>