TIA 1A - TELEVISION INTERFACE ADAPTOR (MODEL 1A)
9 Color Luminance Registers
There are four registers (shown in figure 3) that contain
color-lum codes. Four bits of color code and three its of
luminance code may be written into each of these registers
(COLUP0, COLUP1, COLUPF, COLUBK) by the microprocessor at
any time. These codes (representing 16 color values and 8
luminance values) are given in the Detailed Address List.
The serial graphics output from all six objects is examined
by the priority encoder which activates one of the four
select lines into a 4 x 7 multiplexer. This multiplexer
(shown in figure 3) then selects one of the four color-lum
registers as a 7 line output. Three of these lines are
binary coded luminosity and go directly to chip output
pads. The other four lines go to the color phase shifter.