Normal quotes

28-04.md

@@ -166,55 +166,55 @@
     code ends
     end  Start
 
-### When all Planes “Don’t Care” {#Heading5}
+### When all Planes "Don't Care" {#Heading5}
 
-Still and all, there aren’t all that many uses for basic color compare
+Still and all, there aren't all that many uses for basic color compare
 operations. There is, however, a genuinely odd application of read mode
-1 that’s worth knowing about; but in order to understand that, we must
-first look at the “don’t care” aspect of color compare operation.
+1 that's worth knowing about; but in order to understand that, we must
+first look at the "don't care" aspect of color compare operation.
 
 As described earlier, during read mode 1 reads the color stored in the
 Color Compare register is compared to each of the 8 pixels at a given
-address in VGA memory. But—and it’s a big but—any plane for which the
-corresponding bit in the Color Don’t Care register is a 0 is always
+address in VGA memory. But—and it's a big but—any plane for which the
+corresponding bit in the Color Don't Care register is a 0 is always
 considered a color compare match, regardless of the values of that
-plane’s bits in the pixels and in the Color Compare register.
+plane's bits in the pixels and in the Color Compare register.
 
-Let’s look at this another way. A given pixel is controlled by four
-bits, one in each plane. Normally (when the Color Don’t Care register is
+Let's look at this another way. A given pixel is controlled by four
+bits, one in each plane. Normally (when the Color Don't Care register is
 0FH), the color in the Color Compare register is compared to the four
 bits of each pixel; bit 0 of the Color Compare register is compared to
 the plane 0 bit of each pixel, bit 1 of the Color Compare register is
 compared to the plane 1 bit of each pixel, and so on. That is, when the
-lower four bits of the Color Don’t Care register are all set to 1, then
+lower four bits of the Color Don't Care register are all set to 1, then
 all four bits of a given pixel must match the Color Compare register in
 order for a read mode 1 read to return a 1 for that pixel to the CPU.
 
-However, if any bit of the Color Don’t Care register is 0, then the
+However, if any bit of the Color Don't Care register is 0, then the
 corresponding bit of each pixel is unconditionally considered to match
 the corresponding bit of the Color Compare register. You might think of
-the Color Don’t Care register as selecting exactly which planes should
+the Color Don't Care register as selecting exactly which planes should
 matter in a given read mode 1 read. At the extreme, if all bits of the
-Color Don’t Care register are 0, then read mode 1 reads will always
+Color Don't Care register are 0, then read mode 1 reads will always
 return 0FFH, since all planes are considered to match all bits of all
 pixels.
 
-Now, we’re all prone to using tools the “right” way—that is, in the way
-in which they were intended to be used. By that token, the Color Don’t
+Now, we're all prone to using tools the "right" way—that is, in the way
+in which they were intended to be used. By that token, the Color Don't
 Care register is clearly intended to mask one or more planes out of a
-color comparison, and as such, has limited use. However, the Color Don’t
-Care register becomes far more interesting in exactly the “extreme” case
-described above, where all planes become “don’t care” planes.
+color comparison, and as such, has limited use. However, the Color Don't
+Care register becomes far more interesting in exactly the "extreme" case
+described above, where all planes become "don't care" planes.
 
-Why? Well, as I’ve said, when all planes are “don’t care” planes, read
+Why? Well, as I've said, when all planes are "don't care" planes, read
 mode 1 reads always return 0FFH. Now, when you AND any value with 0FFH,
-the value remains unchanged, and that can be awfully handy when you’re
+the value remains unchanged, and that can be awfully handy when you're
 using the bit mask to modify selected pixels in VGA memory. Recall that
 you must always read VGA memory to load the latches before writing to
-VGA memory when you’re using the bit mask. Traditionally, two separate
+VGA memory when you're using the bit mask. Traditionally, two separate
 instructions—a read followed by a write—are used to perform this task.
 The code in Listing 28.2 uses this approach. Suppose, however, that
-you’ve set the VGA to read mode 1, with the Color Don’t Care register
+you've set the VGA to read mode 1, with the Color Don't Care register
 set to 0 (meaning all reads of VGA memory will return 0FFH). Under these
 circumstances, you can use a single **AND** instruction to both read and
 write VGA memory, since ANDing any value with 0FFH leaves that value