Synchronization

Here is a question that arose:

When drawing a border, its color is taken from the FE port buffer every
8 pixels (or 4 clock cycles), simultaneously with the attributes.
To change the color of the border, you can use any output command.
But the duration of any of them is more than 4 clock cycles (11,12,16,24).
Question: at what clock cycle of the command is it actually possible? does the buffer content change?

Sincerely
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