Normal quotes

25-01.md

@@ -9,7 +9,7 @@ Chapter 25\
 ### The Barrel Shifter, Bit Mask, and Set/Reset Mechanisms {#Heading2}
 
 In the last chapter, we examined a simplified model of data flow within
-the GC portion of the VGA, featuring the latches and ALUs. Now we’re
+the GC portion of the VGA, featuring the latches and ALUs. Now we're
 ready to expand that model to include the barrel shifter, bit mask, and
 the set/reset capabilities, leaving only the write modes to be explored
 over the next few chapters.
@@ -17,9 +17,9 @@ over the next few chapters.
 ### VGA Data Rotation {#Heading3}
 
 Figure 25.1 shows an expanded model of GC data flow, featuring the
-barrel shifter and bit mask circuitry. Let’s look at the barrel shifter
+barrel shifter and bit mask circuitry. Let's look at the barrel shifter
 first. A barrel shifter is circuitry capable of shifting—or rotating, in
-the VGA’s case—data an arbitrary number of bits in a single operation,
+the VGA's case—data an arbitrary number of bits in a single operation,
 as opposed to being able to shift only one bit position at a time. The
 barrel shifter in the VGA can rotate incoming CPU data up to seven bits
 to the right (toward the least significant bit), with bit 0 wrapping
@@ -39,9 +39,9 @@ business) it sounds more useful than it really is. This is because the
 GC can only rotate CPU data, a task that the CPU itself is perfectly
 capable of performing. Two **OUT**s are needed to select a given
 rotation: one to set the GC Index register, and one to set the Data
-Rotate register. However, with careful programming it’s sometimes
+Rotate register. However, with careful programming it's sometimes
 possible to leave the GC Index always pointing to the Data Rotate
-register, so only one **OUT** is needed. Even so, it’s often easier
+register, so only one **OUT** is needed. Even so, it's often easier
 and/or faster to simply have the CPU rotate the data of interest CL
 times than to set the Data Rotate register. (Bear in mind that a single
 **OUT** takes from 11 to 31 cycles on a 486—and longer if the VGA is
@@ -50,16 +50,16 @@ rotate *latched* data, then there would be all sorts of useful
 applications for rotation, but, sadly, only CPU data can be rotated.
 
 The drawing of bit-mapped text is one use for the barrel shifter, and
-I’ll demonstrate that application below. In general, though, don’t knock
+I'll demonstrate that application below. In general, though, don't knock
 yourself out trying to figure out how to work data rotation into your
-programs—it just isn’t all that useful in most cases.
+programs—it just isn't all that useful in most cases.
 
 ### The Bit Mask {#Heading4}
 
 The VGA has bit mask circuitry for each of the four memory planes. The
 four bit masks operate in parallel and are all driven by the same mask
-data for each operation, so they’re generally referred to in the
-singular, as “the bit mask.” Figure 25.2 illustrates the operation of
+data for each operation, so they're generally referred to in the
+singular, as "the bit mask." Figure 25.2 illustrates the operation of
 one bit of the bit mask for one plane. This circuitry occurs eight times
 in the bit mask for a given plane, once for each bit of the byte written
 to display memory. Briefly, the bit mask determines on a bit-by-bit
@@ -74,9 +74,9 @@ given bit of the Bit Mask register is 1, then the corresponding bit of
 data from the ALUs is written to display memory for all four planes,
 while if that bit is 0, then the corresponding bit of data from the
 latches for the four planes is written to display memory unchanged. (In
-write mode 3, the actual bit mask that’s applied to data written to
+write mode 3, the actual bit mask that's applied to data written to
 display memory is the logical AND of the contents of the Bit Mask
-register and the data written by the CPU, as we’ll see in Chapter 26.)
+register and the data written by the CPU, as we'll see in Chapter 26.)
 
 The most common use of the bit mask is to allow updating of selected
 bits within a display memory byte. This works as follows: The display
@@ -93,7 +93,7 @@ capabilities of the GC to draw bitmapped text at any screen location.
 The BIOS only draws characters on character boundaries; in 640x480
 graphics mode the default font is drawn on byte boundaries horizontally
 and every 16 scan lines vertically. However, with direct bitmapped text
-drawing of the sort used in Listing 25.1, it’s possible to draw any font
+drawing of the sort used in Listing 25.1, it's possible to draw any font
 of any size anywhere on the screen (and a lot faster than via DOS or the
 BIOS, as well).