Character Attributes

In NewVic mode, the C4567R6 supports four new character attributes which can be enabled by setting the ATTR bit in Control Register "B". These are Blink, Highlight, Underlined, and Reverse Video characters. Any combination of these attributes can be enabled on a character by character basis, at any time. Certain combinations will have varying effects. (See table below) Attributes can also be applied to bitmap mode, and, to a.limited extent, to the new bitplane mode. (see Bitplanes, below)

Blink is enabled by setting bit 4 of the Color RAM location for each character requring this attribute. The Blink attribute will either flash the character on and off, or will alternately enable and disable the other attributes, if any are selected. The blink rate is approximately 1 Hz.

Reverse Video is enabled by setting bit 5 of the Color RAM location for each character requiring this attribute. Reverse Video is achieved by simply complementing the character image data for each character with this attribute. If the character is also underlined, the underline will be reversed, as well. Highlighted characters also will reverse. Blink, if enabled, will alternately enable and disable this attribute.

Highlight is enabled by setting bit 6 of the Color RAM location for each character requiring this attribute. Highlight is achieved by adding 16 to the color index value. As in the past, the character color is determined by the index value stored in bits 0-3 of the color RAM. In many respects, bit 6 is merely another color select bit. What differs is that the Blink attribute can be used to blink between the "normal" colori and the "highlight' color. Both the character image, and its background can have unique highlight colors.

To use the highlight attribute, effectively, color palette locations 16 through 31 should be programmed to "highlight" colors. (see Palette, below). Highlight colors don't have to be related to normal colors, but can be anything.

Underline is enabled by setting bit 7 of the Color RAM location for each character requiring this attribute. Underline is accomplished by forcing "1" character image data on the eighth raster line for each character with this attribute. If the Blink attribute is also selected, the underline will blink.