Overview
The LC74794 and LC74794M are CMOS LSIs for on-screen display, a function that displays characters and patterns on a TV screen under microprocessor control. They feature a built-in PDC/VPS/UDT interface circuit. These LSIs support 12 × 18 dot characters and can display 12 lines by 24 characters of text.
   
Features
• Display format: 24 characters by 12 rows (Up to 288 characters)
• Character format: 12 (horizontal) × 18 (vertical) dots
• Character sizes: Three sizes each in the horizontal and vertical directions
• Characters in font: 128
• 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
• Blanking: Over the whole font (12 × 18 dots)
• Background color
    — Background coloring: 8 colors (internal synchronization mode): 4fsc
    — Background coloring: 6 colors (internal synchronization mode): 2fsc
    — Blue background only: NTSC
• Line background color
    — Can be set for 3 lines
    — Line background coloring: 8 colors (internal synchronization mode): 4fsc
    — Line background coloring: 6 colors (internal synchronization mode): 2fsc
• External control input: 8-bit serial input format
• On-chip sync separator and AFC circuits
• PDC/VPS/UDT interface circuit
• Composite video output in the PAL or NTSC format