LM1237 National Semiconductor Corporation, LM1237 Datasheet - Page 32

• Manufacturer Part Number: LM1237
• Description: 150 Mhz I2c Compatible Rgb Preamplifier With Internal 254 Character Osd And 4 Dacs
• Manufacturer: National Semiconductor Corporation

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Control Register Definitions
Character Font Access Register
Register Name (address): CHARFONTACC (0x8402)
Vertical Blank Duration Register
Register Name (address): VBLANKDUR (0x8403)
Bit 0
Bit 1
Bits 7–2
Bits 6–0
Bit 7
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.
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.
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