
4 LOOK-UP TABLE (LUT)
C-2-12
EPSON
SID13705 PROGRAMMING NOTES
AND EXAMPLES
Gray Shade Modes
Gray shade modes are monochrome display modes. Monochrome display modes use the Look-Up
Table in a very similar fashion to the color modes. This most significant difference is that the
monochrome display modes use only the intensity of the green element of the Look-Up Table to
form the gray level.
One side effect of using only green for intensity selection is that in gray shade modes there are
only sixteen possible intensities. 8 bit-per-pixel is not supported for gray shade modes.
1 bpp gray shade
When the SID13705 block is configured for 1 bpp gray shade mode, the LUT is limited to
selecting colors from the first two green entries. The two LUT entries can be set to any of sixteen
possible intensities. Typically they would be set to 0h (black) and Fh (white).
Each byte in the display buffer contains eight adjacent pixels. If a bit has a value of “0” then the
color in the green LUT 0 index is displayed. A bit value of “1” results in the color in green LUT 1
index being displayed.
The following table shows the recommended values 1 bpp gray shade display mode
2D
B0
F0
00
6D
70
00
50
AD
50
60
70
ED
30
40
20
2E
70
F0
00
6E
70
00
30
AE
50
60
70
EE
30
40
20
2F
40
F0
00
6F
70
00
10
AF
50
70
EF
30
40
20
30
00
F0
00
70
00
B0
00
40
F0
20
40
20
31
00
F0
40
71
70
10
00
B1
10
00
40
F1
20
40
30
32
00
F0
70
72
70
30
00
B2
20
00
40
F2
20
40
30
33
00
F0
B0
73
70
50
00
B3
30
00
40
F3
20
40
30
34
00
F0
74
70
00
B4
40
00
40
F4
20
40
35
00
B0
F0
75
50
70
00
B5
40
00
30
F5
20
30
40
36
00
70
F0
76
30
70
00
B6
40
00
20
F6
20
30
40
37
00
40
F0
77
10
70
00
B7
40
00
10
F7
20
30
40
38
70
F0
78
00
70
00
B8
40
00
F8
00
39
90
70
F0
79
00
70
10
B9
40
10
00
F9
00
3A
B0
70
F0
7A
00
70
30
BA
40
20
00
FA
00
3B
D0
70
F0
7B
00
70
50
BB
40
30
00
FB
00
3C
F0
70
F0
7C
00
70
BC
40
00
FC
00
3D
F0
70
D0
7D
00
50
70
BD
30
40
00
FD
00
3E
F0
70
B0
7E
00
30
70
BE
20
40
00
FE
00
3F
F0
70
90
7F
00
10
70
BF
10
40
00
FF
00
Table 4-5 Recommended LUT Values for 1 Bpp Gray Shade
Address
Red
Green
Blue
00
01
00
F0
00
02
00
...
00
FF
00
unused entries
Table 4-4 Suggested LUT Values to Simulate VGA Default 256 Color Palette (Continued)
Index
R
G
B
Index
R
G
B
Index
R
G
B
Index
R
G
B