A Microcomputer to Consumer Color TV Interface IC Chip

A MOS/LSI IC to interface a microcomputer to a consumer color television has been designed. It generates an interlaced composite video (Y) and the two color components (R¿Y and B¿Y) to display two intensity and eight color displays in a standard NTSC color receiver. The chip can be configured in one of the fourteen modes of operation, most of which can be switched among themselves on the fly on one screen. Of the fourteen modes, four are alphanumeric, which display 512 characters (16 rows of 32 characters) per screen from an internal (on chip) or external read only memory (ROM). Two semigraphic modes (resolution 64 ×32 and 64 ×48) give the programmer limited graphic capability. The eight graphics modes range in resolution from 64 ×64 to 256 ×192. The chip is designed for easy interface with most 8 bit microprocessors. All refresh memory updating by the CPU is done during vertical retrace and hence is transparent to the screen.