Abstract: An improved method and system for updating a display bitmap with a character string in a given font is provided. Each character in the font is stored as a character bitmap. Each character comprises a contiguous set of virtual characters. A visible stack is created for each character string to be displayed in the display bitmap. For each character to be displayed, the visible stack contains a pointer to each of its virtual characters. The data in the visible stack is then processed to update efficiently the display bitmap. The display bitmap is updated column by column, each column being one byte side. For each byte in the column, the virtual characters that are to be displayed in that byte are combined to form an output byte that is output to the display bitmap. The combining is accomplished by special-purpose routines based on the number of virtual characters that are to be displayed in a particular column.

Abstract: A method and system of displaying a monochrome bitmap on a color display. In a preferred embodiment, a system according to the present invention accomplishes the display of the monochrome bitmap in any two preselected colors. The multibit representations for the two preselected display colors are compared to identify bitmap planes having common bit values for each color. The input for logic units for the identified planes are then forced to 0. The latch registers for each plane of the bitmap memory are then set to the bit value for the first preselected color in that plane. The input values from the monochrome bitmap, as altered by the force-to-0 operation for common planes, are logically exclusively ORed with the latch register values to produce the bitmap memory values for displays. An alternate embodiment suitable for updating partial bytes within the bitmaps is also provided.