LM1236 National Semiconductor Corporation, LM1236 Datasheet - Page 33

• Manufacturer Part Number: LM1236
• Description: 150 Mhz I2c Compatible Rgb Preamplifier With Internal 254 Character Osd Rom, 512 Character Ram And 4 Dacs
• Manufacturer: National Semiconductor Corporation

Bit 0
Bit 1
Bits 7–2
Bits 6–0
Bit 7
Bits 7–0
Control Register Definitions
Character Font Access Register:
Vertical Blank Duration Register:
OSD Character Height Register:
X
X
Enhanced Feature Register 1:
Enhanced Feature Register 2:
Enhanced Feature Register 3:
Bits 8–0
Bits 15–9
Bits 8–0
Bits 15–9
X
X
This is the Color Bit Plane Selector. This bit must be set to 0 to read or write a two-color attribute from the range
0x0000 to 0x2FFF. When reading or writing four-color attributes from the range 0x3000 to 0x3FFF, this bit is set to
0 for the least significant plane and to 1 for the most significant plane. It is also required to set this bit to read the
individual bit planes of the four color character fonts in 0x3000 to 0x3FFF and 0x7000 to 0x7FFF.
This is the Character/Attribute Selector. This applies to reads from the Display Page RAM (address range
0x8000–0x81FF). When a 0, the character code is returned and when a 1, the attribute code is returned.
Reserved. These should be set to zero.
This register determines the duration of the vertical blanking signal in scan lines. When vertical blanking is enabled,
it is recommended that this register be set to a number greater than 0x0A.
Reserved. This bit should be set to zero.
This register determines the OSD character height as described in the section Constant Character Height
Mechanism. The values of this register is equal to the approximate number of OSD height compensated lines
required on the screen, divided by 4. This value is not exact due to the approximation used in scaling the character.
Example: If approximately 384 OSD lines are required on the screen (regardless of the number of scan lines) then
the Character Height Control Register is programmed with 81 (0x51).
X
X
BBHLCTRLB1 (0x8406)
BBLLCTRLB1 (0x8408)
Reserved
Reserved
These determine the button box highlight color.
Reserved. These bits should be set to zero.
These determine the button box lowlight color.
Reserved. These bits should be set to zero.
X
X
Res’d
X
X
X
X
X
X
X
X
Reserved
(Continued)
CHARFONTACC (0x8402)
X
X
CHARHTCTRL (0x8404)
VBLANKDUR (0x8403)
Vertical Blanking Duration
X
Highlight - Green
Lowlight - Green
CH[7:0]
33
VB[6:0]
G[2:0]
G[2:0]
X
X
Heavy Button Box Lowlight/Shading/Shadow
Select
BBHLCTRLB0 (0x8405)
Highlight - Red
BBLLCTRLB0 (0x8407)
ATTR
Lowlight - Red
R[2:0]
R[2:0]
FONT4
Plane
Button Box Highlight Color
Button Box Lowlight Color
Highlight - Blue
Lowlight - Blue
B[2:0]
B[2:0]
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