Abstract: A processor (40) in a data processing system simultaneously loads multiple registers (60) with a single value for fast domain switching. A domain switch instruction asserts a register block write signal (112) along with the register write signal (116) when block writing the single value to the set of registers (60). Register address lines (110, 111) are decoded in two sets: a first set of decoded address lines (110) specifying a block of registers; and the second set (111) specifying one register in the block of registers. When the register block write signal (112) is asserted during a register write, the second set of decoded address lines (111) are ignored, and all registers in the block of registers (60) selected by the first set of decoded address lines (110) are simultaneously loaded with a common value. Additional drive requirements are solved either by adding a buffer (226) to each register bit, or by disabling (228) the feedback path (215) in each register bit during block writes.