both the red and black barber poles(on top and the bottom of the speed tape) are a positioned by the symbol generator based on data supplied to it by the Stall Warning Computer.
as for the yellow extensions from the barber poles...the lower one indicates a .3g margin to stick shaker(or min maneuver speed)...
the upper one indicates .3g margin to high speed buffet at high altitudes.
the source for these again is the Stall Warning Computer based on FMC gross weight calculations.
maybe u'd like to compare the indications of the min man. speed with the fixed speed schedule.. with or without the RPR ...