Overview
The LC74751 is a CMOS LSI that supports on-screen display of characters and patterns on a TV screen under the control of a microcontroller. The LC74751 includes an on-chip character ROM that provides 128 characters in a 12 × 18 dot format. This IC supports display of up to 12 lines of 24 characters each for a maximum of 288 characters.

Features
• Display format: 24 characters by 12 rows
• Characters displayed: Up to 288 characters
• Display control ROM (line ROM): ROM for 64 lines
   (Control in line units: lines consisting of 24 characters)
• Display RAM: 176 characters (Used for the specification
   of user-defined characters.)
• Character format: 12 (horizontal) × 18 (vertical) dots
• Characters in font: 128
• Character sizes: Four sizes each in the horizontal and
   vertical directions
• Initial display positions: 64 horizontal positions and 64
   vertical positions
• Blinking: Specifiable in character units
• Blinking types:
   — Two periods supported: 1.0 second and 0.5 second
   — Three duty types supported: 25%, 50%, and 75%
• Blanking: Over the whole font (12 × 18 dots)
• Background color
   — 8 background colors (in internal synchronization
   mode): 4fsc (NTSC/PAL/PAL-M/PAL-N)
   — 4 background colors (in internal synchronization
   mode): 2fsc (NTSC)
   — Single background color (blue) (in internal
   synchronization mode): 2fsc (PAL/PAL-M/PAL-N)
• External control input: Serial data input
• Synchronizing signals: Supports switching between
   internal and external synchronizing signals.
• On-chip sync separator circuit
• Video output: Composite video output in the NTSC,
   PAL, PAL-M, or PAL-N format
• Superimpose function: Superimposes the character
   output on the composite video output.