There is disclosed a technique for accessing a register file which
comprises defining a first register address as a plurality of bits and
using said first register address to access said register file generating
a second register address by using a sequence of said plurality of bits
with at least one of said plurality of bits supplied via a unitary
operator, the unitary operator being effective to selectively alter the
logical value of said bit depending on its logical value in the first
register address, and using said second register address to access said
register file. A computer system for carrying out such a technique is
also enclosed.