Character display device

Claim 1

A character display device for displaying characters as pixels on a display screen of a display means operating in accordance with a synchronous signal, comprising: a refresh memory for storing character codes in their respective display positions on the display screen; a CPU for accessing said refresh memory and for writing character codes in said refresh memory; first control means for sequentially supplying said refresh memory with addresses for reading the character codes stored therein, thereby causing said refresh memory to sequentially produce the character codes; switching means for selectively connecting said refresh memory with one of said CPU and said first control means, so that the addresses for said refresh memory are supplied from said first control means during production of character codes by said refresh memory and are supplied from said CPU during writing of the character codes in said refresh memory; a character generator responsive to said character codes produced by said refresh memory for producing pixel signals representing character patterns of said character codes; a frame memory responsive to the pixel signals from said character generator for storing the pixel signals at corresponding write addresses for corresponding display positions for each of the respective pixels of said display screen; second control means for sequentially supplying said frame memory with read addresses, thereby causing said frame memory to sequentially produce pixel signals; said second control means operating in accordance with said synchronous signal for said display means; an address counter producing write addresses to said frame memory designating the memory locations of said frame memory at which the pixel signals from said character generator should be written; and means for causing said display means to display the pixel signals produced by said frame memory as pixels on said display screen.