actually used in the print head the physical placement of firing nozzles on the print head referenced above nozzles in two offset rows means that odd and even dots of the same color are for two different lines the even dots are for line l and the odd dots are for line l 2 in addition there is a number of lines between the dots of one color and the dots of another since the 6 color planes for the same dot position are calculated at one time by the hcu there is a need to delay the dot data for each of the color planes until the same dot is positioned under the appropriate color nozzle the size of each buffer line depends on the width of the print head since a single pec generates dots for up to 15 print head segments a single odd or even buffer line is therefore 15 sets of 640 dots for a total of 9600 bits 1200 bytes for example the buffers required for color 6 odd dots totals almost 45 kbytes the entire set of requisite buffers might be provided on the pec chip when manufacturing techniques are capable otherwise the buffers for colors 2 onward may be stored in external dram this enables the pec to be valid even though the distance between color planes may change in the future it is trivial to keep the even dots for color 1 on.