Nintendo NES-001 User Guide - Page 20

second as shown - nes

Get Nintendo NES-001 - Entertainment System Game Console PDF manuals and user guides View all Nintendo NES-001 manuals
Add to My Manuals
Save this manual to your list of manuals

Page 20 highlights

is 33221100 where every two bits specifies the most significant two colour bits for the specified square. Square 0 $0 $1 $2 $3 Square 1 $4 $5 $6 $7 Square 2 $8 $9 $A $B Square 3 $C $D $E $F Figure 3-3. 4x4 tile group layout. Adapted from [20]. The NES only has 2 KB to store name tables and attribute tables, allowing it to store two of each. However it can address up to four of each. Mirroring is used to allow it to do this. There are four types of mirroring which are described below, using abbreviations for logical name tables (those that can be addressed), L1 at $2000, L2 at $2400, L3 at $2800 and L4 at $2C00: • Horizontal mirroring maps L1 and L2 to the first physical name table and L3 and L4 to the second as shown in figure 3-4. 11 22 Figure 3-4. Horizontal mirroring. • Vertical mirroring maps L1 and L3 to the first physical name table and L2 and L4 to the second as shown in figure 3-5. 12 12 Figure 3-5. Vertical mirroring. 20

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
20
is 33221100 where every two bits specifies the most significant two colour bits for the
specified square.
Square 0
$0
$1
$2
$3
Square 1
$4
$5
$6
$7
Square 2
$8
$9
$A
$B
Square 3
$C
$D
$E
$F
Figure 3-3. 4x4 tile group layout. Adapted from [20].
The NES only has 2 KB to store name tables and attribute tables, allowing it to store two of
each. However it can address up to four of each. Mirroring is used to allow it to do this. There
are four types of mirroring which are described below, using abbreviations for logical name
tables (those that can be addressed), L1 at $2000, L2 at $2400, L3 at $2800 and L4 at
$2C00:
•
Horizontal mirroring maps L1 and L2 to the first physical name table and L3 and L4 to the
second as shown in figure 3-4.
1
1
2
2
Figure 3-4. Horizontal mirroring.
•
Vertical mirroring maps L1 and L3 to the first physical name table and L2 and L4 to the
second as shown in figure 3-5.
1
2
1
2
Figure 3-5. Vertical mirroring.